RECOMMENDED PRACTICE
DNV-RP-J203
Geological Storage of Carbon Dioxide
APRIL 2012
This document has been amended since the main revision (April 2012), most recently in July 2013.
See “Changes” on page 3.
The electronic pdf version of this document found through http://www.dnv.com is the officially binding version
DET NORSKE VERITAS AS
FOREWORD
DNV is a global provider of knowledge for managing risk. Today, safe and responsible business conduct is both a license
to operate and a competitive advantage. Our core competence is to identify, assess, and advise on risk management. From
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DNV service documents consist of among others the following types of documents:
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— Standards. Technical requirements.
— Recommended Practices. Guidance.
The Standards and Recommended Practices are offered within the following areas:
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© Det Norske Veritas AS April 2012
Any comments may be sent by e-mail to [email protected]
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any use of this document.
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Changes – Page 3
CHANGES – CURRENT
General
This is a new document.
Amendment July 2013
— An editorial correction has been made in the first row of Table 5-1.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Contents – Page 4
CONTENTS
CHANGES – CURRENT .................................................................................................................................. 3
1.
Preface..................................................................................................................................................... 5
2.
Introduction............................................................................................................................................ 5
2.1 General......................................................................................................................................................5
2.2 Objective ...................................................................................................................................................5
2.3 Approach...................................................................................................................................................5
2.4 Scope.........................................................................................................................................................5
2.5 Users .........................................................................................................................................................6
2.6 Relationship to other codes.......................................................................................................................6
2.7 Structure of this document ........................................................................................................................7
3.
Definitions and abbreviations ............................................................................................................... 8
3.1 Definitions.................................................................................................................................................8
3.2 Abbreviations..........................................................................................................................................12
3.3 Verbal Forms ..........................................................................................................................................12
4.
Storage Site Screening and Appraisal................................................................................................ 13
4.1 Introduction.............................................................................................................................................13
4.2 Screening.................................................................................................................................................13
4.3 Appraisal ................................................................................................................................................17
5.
Permitting ............................................................................................................................................. 26
5.1 Introduction.............................................................................................................................................26
5.2 Permit context and requirements (Step 1, Figure 5-1)............................................................................26
5.3 Risk performance targets (Step 2, Figure 5-1)........................................................................................27
5.4 Storage Permit application (Step 3, Figure 5-1) .....................................................................................27
5.5 Closure Permit application (alternative Step 3, Figure 5-1) ...................................................................32
5.6 Evaluate completeness (Step 4, Figure 5-1) ...........................................................................................34
5.7 Submit application (Step 5, Figure 5-1)..................................................................................................34
6.
Risk management................................................................................................................................. 35
6.1 Introduction.............................................................................................................................................35
6.2 Risk management context .......................................................................................................................35
6.3 Risk Assessment .....................................................................................................................................37
6.4 Risk treatment .........................................................................................................................................39
6.5 Risk management review and documentation ........................................................................................40
7.
Well qualification ................................................................................................................................. 41
7.1 Introduction.............................................................................................................................................41
7.2 Set requirements in qualification basis ...................................................................................................42
7.3 Risk assessment for well qualification....................................................................................................43
7.4 Plan well qualification & select qualification activities .........................................................................45
7.5 Evaluate likelihood of success ................................................................................................................46
7.6 Evaluate need for modifications .............................................................................................................47
7.7 Update qualification basis.......................................................................................................................47
7.8 Initial Well Qualification Report ............................................................................................................47
7.9 Execute well qualification activities .......................................................................................................47
7.10 Performance Assessment ........................................................................................................................48
7.11 Requirements met?..................................................................................................................................48
7.12 Final Well Qualification Report..............................................................................................................48
Appendix A. Subsurface Data ...................................................................................................................... 49
Appendix B. Generic failure modes for well integrity
under exposure to Carbon Dioxide............................................................................................................... 54
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Sec.1 Preface – Page 5
1 Preface
The main objective of this Recommended Practice (RP) is to provide a systematic approach to the selection,
qualification and management of geological storage sites for carbon dioxide (CO2). This RP specifies what, in
DNV’s opinion, is the best industry practice for that purpose.
This RP may be used as a basis for verification and is considered applicable worldwide.
2 Introduction
2.1 General
There is growing consensus that global warming and climate change are the anthropogenic results of
greenhouse gas emissions from the combustion of fossil fuels, such as natural gas, oil and coal. The world's
population is steadily growing, as are its energy needs. It is expected that a significant part of the world's future
need for electrical energy and heat will come from burning of fossil fuels, implying increased CO2 emissions
to the atmosphere.
Carbon Capture and Storage (CCS) offers an opportunity to mitigate global warming and associated negative
impacts by capturing and storing CO2 that would otherwise be emitted to the atmosphere. CCS refers to the
process of capturing CO2 from large point sources, such as fossil fuel power plants, cement factories, oil
refineries, or iron and steel mills, and injecting and isolating the captured CO2 in deep geological formations.
For CCS to be effective the geological formations into which CO2 is injected must be carefully selected and
qualified to ensure that they can provide long-term containment of injected CO2 streams.
2.2 Objective
This RP provides users with systematic procedures and performance requirements for assessing and verifying
the suitability of storage sites and projects for environmentally safe, long-term geological storage of injected
CO2 streams. This includes assessment and verification of monitoring and risk management plans tailored to
the characteristics of each storage site.
2.3 Approach
This RP applies the principles of Technology Qualification given in DNV-RP-A203 to managing the technical
risks related to CO2 geological storage. Technology Qualification is a methodology developed by DNV for
reducing the risk and uncertainty associated with implementation of new technology. The following principles
shall control the qualification process:
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specifications and performance requirements shall be clearly defined, quantified and documented
a qualification plan shall be developed to evaluate fulfilment of the specified requirements
threats to the performance requirements shall be identified
tailored threat identification should be carried out for novel elements where the uncertainty is most
significant
the relevance of individual threats shall be determined based on their risk
risk assessments shall be executed and documented in a transparent and traceable way
risk assessments shall be used to evaluate the appropriateness of requirements and to guide decision making
the qualification process and the evaluation of fulfilment of performance requirements shall be
documented.
2.4 Scope
2.4.1 General
This RP defines performance requirements and procedures for the following:
— the selection and qualification of geological storage sites for long-term storage of CO2
— the documentation of storage site characterization and storage site development plans as a basis for permit
applications/reviews
— risk management throughout life cycle of CO2 geological storage projects, from initial screening and
storage site selection through to storage site closure and preparation for post-closure stewardship
— monitoring and storage performance verification
— well assessment and management planning
— storage site closure and preparation for post-closure stewardship.
Where the term CO2 is used in the guideline, it assumes that carbon dioxide is pressurized; may or may not
contain water; exists either as a liquid, super critical fluid or a gas; and also includes carbon dioxide dissolved
in water contained in the injection zone.
DET NORSKE VERITAS AS
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Recommended Practice DNV-RP-J203, April 2012
Sec.2 Introduction – Page 6
2.4.2 Qualification requirements
The following qualification requirements are summarized in tables throughout the document:
— Table 4-1: Requirements to potential storage sites that should be included in the Screening Basis.
— Table 4-3: Requirements to prospective storage sites that shall be included in the Appraisal Basis (in
addition those listed in Table 4-1).
— Table 5-2: Requirements for storage site closure.
— Table 5-3: Requirements for the Storage Development Plan.
— Table 5-1: Requirements for the Monitoring Plan.
2.4.3 Exclusions
This RP does not include performance requirements or recommended procedures for:
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the selection and qualification of hydrocarbon fields for enhanced recovery by CO2 injection
the capture of CO2 and its transportation from source to storage site
management of surface facilities and well operations (injection wells, production wells, monitoring wells)
accounting of CO2 emissions avoided
CO2 injection and storage in un-mineable coal beds, basalt formations, shales, and salt caverns
underground storage in materials involving the use of any form of engineered containers.
2.4.4 Application
This RP may be applied as a basis for verification and risk-based decision making, including but not limited to:
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guidance and quality assurance of storage site planning and development
demonstration of compliance with industry best practice
implementation of regulations
independent assessment and verification
stakeholder communication.
The requirements in this RP shall be subordinate to local regulations.
2.5 Users
Users of this RP may typically be:
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an operator
a regulator
an independent verifier
an investor or other financial stakeholder.
2.6 Relationship to other codes
Generic qualification procedures for new technology are given in DNV-RP-A203. While these procedures
cover a generic approach, the present document describes how these principles shall be applied to qualify and
manage CO2 geological storage sites.
Only the storage component of the CCS value chain from the injection zone up to and including the CO2
injection well heads is addressed in this RP. Elements of the capture and (pipeline) transport components of the
CCS chain are given in DNV-RP-J201 and DNV-RP-J202, respectively.
This RP incorporates and combines the guidance given in the following two documents:
— CO2QUALSTORE – Guideline for Selection and Qualification of Sites and Projects for CO2 Geological
Storage of CO2 (2010).
— CO2WELLS – Guideline for the Risk Management of Existing Wells at CO2 Geological Storage Sites
(2011).
These two guidelines were the final deliverables from joint industry projects whereas this RP has been
developed, and will be maintained, by DNV.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Sec.2 Introduction – Page 7
2.7 Structure of this document
1
2
3
4
5
6
7
8
Initiate
Project
Select
Prospective Sites
Select
Storage Site
Storage Permit
application
Initiate
Construction
Initiate CO2
Injection
Qualify for
Site Closure
Decommision
Screening
EP
Appraisal
Permitting
SP
Design
Construct
Operate
Close
TOR
Risk Management
Screening & Appraisal
Permitting
Permitting
Well Qualification
EP – Exploration Permit
SP – CO2 Storage Permit
TOR – Transfer of Responsibility
Figure 2-1
Life cycle diagram for a CO2 geological storage project showing decision gates (diamonds) and permits (stars). The
sections within this RP are shown underneath the relevant life cycle stages as grey bars.
This document is structured around the generic decision gate model for a CO2 storage site, as shown in Fig.21. The decision gate model covers the life cycle of a CO2 geological storage project. Decision gates 2, 4 and 8
are designed to precede an operator’s application for an exploration permit, storage permit and transfer of
responsibility permit, or their equivalents.
This RP contains the following sections:
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Section 4: Storage Site Screening and Appraisal
Section 5: Permitting
Section 6: Risk Management
Section 7: Well Qualification.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
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Sec.3 Definitions and abbreviations – Page 8
3 Definitions and abbreviations
3.1 Definitions
Term
Definition
Accounting and Reporting One component of a Storage Development Plan. It is a document that describes how an
Plan
operator shall account for and report avoided emissions of CO2 for regulators and/or
emissions trading schemes. The content and structure of the Accounting and Reporting plan
is not described in this document because this is expected to be prescribed by regulations and/
or requirements of an emissions trading scheme.
Acid gas
Natural gas or gas mixture which contains significant amounts of hydrogen sulfide (H2S)
and/or CO2.
Appraisal Communication A plan that describes how the operator intends to communicate with the relevant stakeholders
Plan
that influenced the requirements in the Appraisal Basis
Appraisal Basis
A document that defines the requirements to be fulfilled during the project Appraisal stage
in order to be qualified to apply for a Storage Permit.
Appraisal Plan
A document that describes the scope of each step in the Appraisal stage and the activities to
be carried out.
Appraisal Risk Assessment A report that documents the activities undertaken during the Appraisal stage risk assessment.
Report
Appraisal stage
The second project life cycle stage in a CO2 geological storage project.
Appraisal Report
A report that documents the activities undertaken during the Appraisal stage, which storage
sites are qualified to apply for a Storage Permit and the evidence for making this decision.
Biosphere
Realm of living organisms in the atmosphere, on the ground, in the oceans and seas, in
surface waters, and in the subsurface at depths above which water salinity is less than limits
defined for groundwater. See also Groundwater.
Capacity
Accumulated mass of CO2 that can be injected into injection zone(s) while maintaining
storage integrity.
Capillary entry pressure
The capillary pressure at which the non-wetting phase starts to displace the wetting phase,
usually brine, contained in the largest pore throat within a water-wet formation.
Carbon dioxide (CO2)
Non-polar chemical compound composed of two oxygen atoms covalently bonded to a single
carbon atom (O=C=O).
Cement plug
Volume of cement slurry placed in a wellbore which, once in a solid state, shall function as
a well barrier.
Characterization Report
A report that documents the storage site characterization activities that have been carried out,
which storage sites remain prospective and that the storage site characterization is sufficient
to support the selection of a final storage site.
Closure
see Storage site closure.
Closure Basis
A document that defines the requirements to be fulfilled during the project Closure stage in
order to be able to regard a storage site as qualified for Closure.
Closure Plan
One component of a Storage Development Plan. It is a document that describes closure
requirements for a given storage site and the qualification process that shall be used to
demonstrate fulfillment of these requirements.
Closure Permit
Written decision issued by a designated regulatory authority authorizing closure of a CO2
storage site.
Closure Qualification
One component of a Storage Closure application. It is a document that includes a description
Statement
of the Closure Basis, an Environmental Statement for storage site closure, a Storage
Performance Forecast for storage site closure, a Monitoring Plan for storage site closure and
an updated Closure Plan.
CO2
Carbon dioxide. As used in this RP it assumes that carbon dioxide is pressurized; may or may
not contain water; exists either as a liquid, super critical fluid or a gas; and also includes
carbon dioxide dissolved in water contained in the reservoir.
CO2 geological storage
CO2 injection accompanied by storage of injected CO2 streams in a geological formation.
CO2 geological storage
Component of a carbon capture and storage project that includes site screening, selection and
project
appraisal, permitting, design and construction of site facilities, well drilling, operation of
CO2 geological storage, storage site closure (including well and facilities abandonment), and
post-closure. It also includes monitoring during all project phases.
CO2 injection
Well operation injecting a CO2 stream into a designated injection zone.
CO2 plume
Dispersing volume of CO2 stream not dissolved in resident formation fluids.
CO2 stream
A flow of substances which consists of a sufficiently high fraction of CO2 and sufficiently
low concentrations of other substances to meet specifications of streams permitted for longterm CO2 geological storage.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Term
Communication Plan
Consequence
Consequence category
Containment
Corrective control
Dense phase conditions
Economic receptor
Elevated pressure
Environmental receptor
Environmental Statement
Event
Event-consequence
scenario
Failure mechanism
Failure mode
Flowline
Formation fluid
Fracture
Geological fault
Geomechanical stability
Geosphere
Groundwater
Impact hypothesis
Injection and Operating
Plan
Injection zone
Injectivity (1)
Injectivity (2)
Leakage
Leakage pathway
Recommended Practice DNV-RP-J203, April 2012
Sec.3 Definitions and abbreviations – Page 9
Definition
One component of a Storage Development Plan. It is a document that shall describe when
and how the operator shall communicate with project stakeholders including providing
information about environmental impact and risk treatment.
Outcome of an event affecting objectives
A subject of concern for which risk is evaluated and managed, for example human health and
safety, environmental protection and storage site performance.
Prevention of leakage at rates or in total mass sufficient to cause adverse impact.
Mitigative control intended to limit the scale and duration of unintended consequences, such
as leakage or pressure build-up in unintended zones or above desired levels, and to restore
the integrity of a storage site and/or the quality of economic or environmental receptors that
have been affected by the CO2 geological storage project.
Conditions for which CO2 will be in a liquid or supercritical phase.
Subsurface domain or formation that is or has potential to be an economic resource, e.g.,
hydrocarbon reservoirs, coal seams, formations with high geothermal energy conversion
potential, mineral resources, etc.
Pressure sufficient to cause movement of formation fluids from the storage complex through
a high permeable pathway into an economic or environmental receptor above the storage
complex.
Biosphere, surface area above storage site or other subsurface domain or formation
designated for conservation purposes that may be polluted or negatively impacted by the CO2
geological storage project.
One component of a Storage Development Plan. It is a document that documents the outcome
of an Environmental Impact Assessment or an equivalent process.
Discrete occurrence or change of a particular set of circumstances over a short period of time.
Chain of circumstances upon which a consequence with negative impact on a risk category
may arise as a result of the event.
The physical, chemical or other process that may lead to, or has led to, a failure.
Potential or observed manner of failure on a specified level of a well component or system
of components.
A surface pipeline carrying an injection or production stream that connects the wellhead to a
manifold or to injection or production facilities, such as a compressor.
Fluid or gas occupying pore-space in a geological formation.
A crack or surface of breakage within rock not related to foliation or cleavage in
metamorphic rock along which there has been no movement.
A displacement of rocks along a shear surface. The surface along which displacement occurs
is called the fault plane (often a curved surface).
Prevention of adverse impact caused by induced seismicity, fracturing or earth deformation
as a result of CO2 injection.
The solid earth below the ground surface and bottom of rivers and water bodies on land, and
below the sea bottom offshore.
Water located beneath the ground surface and characterized by having low concentrations of
dissolved salts and other total dissolved solids.
Concise statement of the expected consequences – both positive and negative – to the risk
categories of the storage site contingent upon execution of the risk management plan.
One component of a Storage Development Plan. It is a document that includes the final Well
Engineering Concept and final Well Qualification Report for each well at a storage site and
describes the following characterisitics; i) the expected injection forecast, ii) the expected
variation in delivered well performance and iii) well operating procedures.
A geologic formation, group of formations, or part of a formation into which CO2 is or will
be injected for the purpose of long-term storage.
The possible CO2 injection rate that can be achieved through a specified well subject to
(bottom-hole or other) injection pressure constraints.
The possible CO2 injection rate for a given storage site that can be achieved subject to
reservoir pressure or other injection pressure constraints.
Measurable release of CO2 stream constituents or displaced formation fluid from a storage
complex that detrimentally impacts an economic or environmental receptor as a result of
project activity.
Natural or engineered feature or combination of features through which CO2 stream
constituents or formation fluids displaced by CO2 injection can potentially migrate outside
of the storage complex. For example geological faults, wells, permeable horizons, outcrops
and spill points.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Sec.3 Definitions and abbreviations – Page 10
Term
Level of risk
Definition
Magnitude of a risk or combination of risks, expressed in terms of the combination of
consequences and their likelihood.
Likelihood
Chance of something happening expressed either qualitatively or quantitatively and
described using general terms or mathematically, such as a probability or a frequency over a
given time period.
Life cycle of a storage site Time span from initial planning and execution of storage site screening to post-closure
stewardship phase (see Storage site closure).
Long-term
Minimum period of retention of injected CO2-streams in subsurface geological formations
necessary for CO2 geological storage to be considered an effective and environmentally safe
climate change mitigation option.
Mitigative control
Risk control to prevent or reduce adverse effects of events.
Modelling Report
A report that documents the activities undertaken during the modelling step of the Appraisal
stage and the results obtained.
Monitoring
Measurement and surveillance activities necessary for ensuring safe and reliable CO2
geological storage.
Monitoring Plan
One component of a Storage Development Plan. It is a document that describes the
monitoring objectives, targets, techniques and activities for a storage site.
Monitoring target
A measurable physical property or characteristic at a given location that can provide an
indicator of compliance or non-compliance with defined requirements for storage site
performance.
Operator
Natural or legal, private or public person, business organization(s) or government entity who
operates and controls the CO2 geological storage operation or to whom decisive power over
the storage operation has been delegated according to regulations.
Overburden
Sedimentary succession (stratigraphic column) overlying a reference underground
formation.
Plug and Abandon
Action taken to ensure permanent isolation of fluids and pressures from exposed permeable
zones along well trajectory by installation of well barriers, usually cement plugs.
Passive control
Risk control naturally inherent in the CO2 geological storage site or in the engineered
components associated with the system.
Performance margin
Margin to non-compliance with performance requirements.
Performance requirement Requirement used to evaluate the success of a performance assessment.
Permeability
Measure of the ability of a soil or rock to transmit fluids.
Porosity
Ratio of the volume of void pore space in the rock relative to the bulk volume of the rock.
Preventive control
Risk control to prevent or reduce the likelihood of an event.
Qualification
A process of providing the evidence that a technology or CO2 storage site will function
within specific limits with an acceptable level of confidence.
Regulator
Relevant national, state or provincial authority and/or international regulatory body.
Risk
Effect of uncertainty on objectives. Risk may be expressed in terms of a combination of a
likelihood of occurrence of an event and the associated severity of potential consequences
that may arise as a result of the event.
Risk analysis
Process to comprehend the nature of risk and determine the level of risk.
Risk assessment
Overall process of risk identification, risk analysis and risk evaluation.
Risk control
Measure or inherent characteristic whose purpose is to reduce risk.
Risk evaluation
Process of comparing the results of risk analysis with the evaluation risk criteria to determine
whether the risk and/or its magnitude are/is acceptable or tolerable.
Risk evaluation criteria
Terms of reference against which the significance of a risk is evaluated. Note that this
definition is equivalent to the definition of ‘risk criteria’ in ISO 31000.
Risk identification
Process of finding, recognizing and describing risks.
Risk Management Plan
One component of a Storage Development Plan. It is a document that describes how risks to
a storage site shall be managed in the Operate and Close stages of a project.
Risk owner
Person or entity with the accountability and authority to manage the risk.
Risk performance target
For a specified risk, the target level of risk to be achieved through implementation of a
prescribed risk treatment.
Risk scenario
Combination of a threat-event scenario and possible event-consequence scenarios.
Risk treatment
Process to modify risk through implementation of risk controls.
Seal
Relatively impermeable rock, commonly shale, anhydrite or salt that forms a barrier or seal
above and around reservoir rock so that fluids cannot migrate beyond the reservoir. The
permeability of a seal capable of retaining fluids through geologic time is typically in the
range 10-6 to 10-8 Darcies.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Term
Screening Basis
Screening Plan
Screening stage
Screening Report
Significant event
Significant risk
Spill point
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Sec.3 Definitions and abbreviations – Page 11
Definition
A document that defines the requirements to be fulfilled during the project Screening stage
in order to be able to regard a storage site as prospective and thereby qualified for appraisal.
A document that describes the scope of each step in the Screening stage and the activities to
be carried out.
The first project life cycle stage in a CO2 geological storage project.
A report that documents the activities undertaken during the Screening stage presents the
evidence for selecting prospective storage sites that qualify for appraisal.
Circumstance or set of circumstances with potential to have significant impact on a
consequence category.
Risk whose magnitude must be reduced through implementation of appropriate risk
treatment to maintain alignment with project objectives.
Structurally lowest point in a structural trap that can retain buoyant fluids.
Stakeholder
Individual, group of individuals, or organization whose interests are substantially affected by
the project. Stakeholders can include employees, shareholders, community residents,
suppliers, customers, non-governmental organizations, governments, regulators, labour
unions, and other individuals or groups.
Storage complex
Subsurface volume delineated by the operator and approved by the regulator for the purpose
of environmentally safe long-term containment of injected CO2 streams.
Storage Development Plan A generic term used in this document to refer to the package of documentation that an
operator shall submit to a regulator in order to apply for a Storage Permit. Comparable to a
Plan for Development and Operations for hydrocarbon fields. DNV recognises that the name
of this document and required content may vary depending on jurisdiction.
Storage integrity
Ability of storage complex to provide long-term containment and geomechanical stability
when CO2 geological storage operations are managed in accordance with the Injection and
Operating Plan.
Storage Performance
One component of a Storage Development Plan. It is a document that provides a scenarioForecast
based storage performance forecast that demonstrates the suitability of the Injection and
Operating Plan in meeting the storage site performance requirements defined in the Appraisal
Basis.
Storage permit
Written decision issued by a designated regulatory authority authorizing CO2 injection by an
operator into a specified injection zone for the purpose of permanent containment within a
defined CO2 geological storage complex, and which specifies the conditions under which
CO2 injection and storage operations may take place.
Storage site
Storage complex and the wells and surface facilities associated with the operation,
monitoring and risk management of the storage site.
Storage site closure
Milestone in the CO2 geological storage project after cessation of CO2 injection upon which
operation changes from actively managing risks through cycles of modelling, monitoring and
risk assessments, to a post-closure stewardship phase focusing on providing continued
assurance that risks are maintained at an acceptable level.
Stratigraphic column
Sedimentary succession of geological formations in region of interest for CO2 geological
storage.
Technical Appraisal Plan A document that shall describe how storage site characterization and modelling activities will
be performed for each prospective storage site in order to provide the technical basis for the
storage site and well engineering concept selection.
Threat
Element which alone or in combination has the intrinsic potential to give rise to risk.
Threat-event scenario
Chain of circumstances upon which the threat may cause the event to occur.
Verification
Confirmation by examination and provision of objective evidence that specified
requirements have been fulfilled, usually a quality assurance process of determining
compliance with a regulation, standard or specification.
Well barrier
Envelope of one or several dependent components preventing fluids or gases from flowing
unintentionally between geological formations or to the surface.
Well component
Individual pieces of equipment which are joined together as part of well construction.
Well Engineering Concept A document that describes the well engineering solution for new and existing wells at
concept level for a prospective storage site.
Well integrity
The ability of a well to perform its required function effectively and efficiently whilst
preventing uncontrolled release of formation fluids along the wellbore throughout the life of
the well.
Well Qualification
The process of providing the evidence that a given well will function within specific limits
with an acceptable level of confidence.
Well Qualification Basis A document that defines the requirements to be fulfilled during the qualification of a given
well, including a description of the current status of the well, the well performance
requirements, the well specification and the critical parameters.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
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Sec.3 Definitions and abbreviations – Page 12
Term
Definition
Well Qualification Report A report that documents the activities performed during Well Qualification, the fitness for
purpose of a given well and the defined margins against specified failure modes or
performance targets.
Wellbore
The physical hole that makes up the well.
3.2 Abbreviations
ALARP
CCS
CO2
HSE
As Low as Reasonably Practicable
Carbon Capture and Storage
Carbon Dioxide
Health, Safety and Environment.
3.3 Verbal Forms
For verification of compliance with this RP, the following definitions of the verbal forms, shall, should and
may are applied:
Shall: indicates a mandatory requirement to be followed for fulfilment or compliance with the present RP.
Should: indicates a recommendation that a certain course of action is preferred or particularly suitable.
May: indicates permission, or an opinion, which is permitted as a part of conformance with the RP.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
Sec.4 Storage Site Screening and Appraisal – Page 13
4 Storage Site Screening and Appraisal
4.1 Introduction
This chapter describes the recommended procedure for identifying potential storage sites in a given region,
screening those that are prospective and developing one or more to a level of maturity suitable for beginning
the process of applying for a Storage Permit at Milestone M3 in Figure 2-1.
4.2 Screening
4.2.1 General
The purpose of storage site screening is to evaluate the potential for CO2 geological storage in a given region.
The following steps represent a generic recommendation of screening activities applicable to any region. The
scope of the steps is expected to vary between regions depending on the quality and quantity of existing data.
The output from storage site screening should be a list of potential storage sites that fulfil the operator’s
requirements laid down in the Screening Basis. The screening process shall be documented in a Screening
Report.
4.2.2 Screening Basis
The purpose of the Screening Basis is to provide a common set of requirements against which all potential
storage sites will be assessed at Milestone M2 in Figure 2-1.
The Screening Basis document should include a list of requirements that a storage site should fulfil in order to
be regarded as prospective and qualify for appraisal. These requirements should at least include those listed in
Table 4-1.
Table 4-1 Requirements to potential storage sites that should be included in the Screening Basis
1) A quantitative requirement for minimum total capacity (tonnes)
2) A quantitative requirement for minimum annual injectivity (tonnes/year)
a) depth: sufficient depth of injection zone to achieve CO2 dense phase conditions
(> 300 kg/m3 at reservoir conditions)
b) seal: presence of laterally extensive seal above the injection zone to prevent flow
communication with economic and/or environmental receptors
c) wells: confidence that well integrity can be established and maintained in existing
3) A requirement for documented
wells that penetrate the primary seal and will be exposed to CO2 or pressure changes
evidence of the following positive
i) sufficiently stable geological
indicators of long-term
environment to give confidence that
containment:
containment will not be jeopardized by
natural tectonic activity
d) geological faults:
ii) absence of existing flow-paths along
geological faults that penetrate the storage
complex
4) A requirement for documented
evidence of the following positive a) legal availability of the storage site over the expected life cycle
indicators of the potential to
monitor and deploy risk treatment: b) physical accessibility to the storage site over the expected life cycle
The Screening Basis document should also describe the context in which the screening activity is taking place.
The context may be described by the following:
—
—
—
—
the locations of the current or planned sources of CO2
the mass rates and composition of the CO2 streams from these sources
the expected rates of supply and the lifetime of the CO2 sources
the natural environment such as meteorology, surface/marine environment, biosphere, hydrosphere and
geosphere in as far as it may interact with the storage complex or potential leaks from the complex
— historical, existing or planned uses of the subsurface in the region, such as:
—
—
—
—
—
—
groundwater extraction
oil or gas production
geothermal energy extraction
acid gas disposal
natural gas storage
waste disposal
— historical, existing or planned land use in the region for onshore storage sites, such as:
— population centres (taking into account demographic trends)
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—
—
—
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industrial developments
agriculture
transport infrastructure such as roads and railways
industrial infrastructure such as pipelines and power lines
— protected and sensitive areas such as:
—
—
—
—
nature reserves (on land or marine)
indigenous reserves
military areas
drinking water sources
— the social and cultural context around a storage site, including public perceptions of CO2 geological storage
and related issues in the region
— the legal and regulatory environment for CO2 geological storage in the region
— the expectations of the operator, regulators and stakeholders to the screening process.
4.2.3 Screening Plan
The purpose of the Screening Plan is to describe the scope of each screening step and the activities to be carried
out.
The planned activities should be appropriate for the type of data that will be used and the level of detail required
for comparison against the requirements set out in the Screening Basis.
The Screening Plan document should describe the following:
—
—
—
—
—
—
—
—
—
—
the data that will be used for screening
where this data will be obtained
how this data will be used to identify potential storage sites
how storage capacity will be calculated
how existing wells will be identified and risk assessed
how other potential leakage risks will be identified and risk assessed
how potential conflicts with other sub-surface resources or land-use claims will be identified
how the location of potential storage sites will be evaluated with respect to the location of CO2 sources
which stakeholders will be involved or informed during the screening process
stakeholder’s needs for information and involvement, providing the rationale for the communication
strategy and for future engagement
— how legal and physical accessibility to storage sites will be assessed.
4.2.4 Data Collection and Review
The purpose of this step is to collect and review data in order to identify potential storage sites.
This activity may primarily be based on data available from existing sources, but acquisition of new data
through early-stage appraisal activities may be needed in data poor areas. An operator should consider the
likelihood of getting necessary public support for undertaking CO2 storage in a given region, which may entail
public surveys and stakeholder interviews.
Data review should identify geological structures that demonstrate the potential to comply with the
requirements in the Screening Basis and document these as potential storage sites.
Examples of the types of data that may be collected and the information that may be derived from each are
given in Appendix A.
Guidance note:
For regions with a large number of possible storage sites, this step may require an iterative approach that may use
indicative storage site screening requirements as a first step. Such requirements may be used to rank storage sites
according to suitability for CO2 storage. Geographical Information System tools and datasets may be utilized to
facilitate recording and visualization of such ranking parameters.
The main purpose of screening requirements is to enable compilation of aggregate ranking scores indicative of storage
site suitability to help accelerate and guide the screening process by rapidly identifying the most promising areas for
CO2 geological storage. Screening requirements should not be interpreted as thresholds for elimination of prospects
with unfavorable characteristics. The suitability of a potential storage site will ultimately need to be demonstrated
through detailed storage site-specific assessments. To this end, storage sites with certain unfavorable characteristics
may in the end still prove to be suitable.
Furthermore, while generic screening requirements may be applied to assign indicative suitability scores, additional
requirements may be added to reflect the purpose of the storage site, including potential social, cultural, technical or
economic constraints. For further information about screening requirements see:
IEA Greenhouse Gas R&D Programme (IEA GHG). 2009. CCS Site Characterisation Criteria, Report No. 2009/10.
Cheltenham. United Kingdom.
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4.2.5 Uncertainty Assessment
4.2.5.1 General
The purpose of this step is to assess the level of uncertainty related to each potential storage site that was
identified in the preceding step.
The quality and quantity of the available evidence for and against meeting the requirements laid down in the
Screening Basis should be assessed for each potential storage site.
Critical pieces of missing information that would reduce the uncertainty for a given storage site should also be
identified and recorded for use in developing an eventual Appraisal Plan.
4.2.5.2 Capacity
Initial estimates of storage capacity can be obtained using a number of different methods that span a range of
complexities. Three broad groups of capacity estimation methods are volumetric methods, analytical or semianalytical methods, and numerical reservoir simulation methods. For these categories the uncertainty attached
to capacity estimates may be assessed by using the following approaches:
— for volumetric based capacity estimation methods the uncertainty may be reflected by providing
conservative and optimistic estimates of the volumetric fraction of the pore-space that can be filled with
CO2. For closed contour structures the capacity is usually not more than 1-2 percent of the accessible porevolume due to limits on pressure build-up. (Note that this ratio may be significantly increased if the
reservoir has been depleted by hydrocarbon production). Other factors, such as preferential flow paths and
internal flow barriers, may further reduce the capacity.
— for capacity estimation methods that include modelling of the CO2 plume movement and pressure build-up
in an analytical or semi-analytical fashion it may be possible to do sensitivity analysis of the primary
uncertain parameters that describe the pore volume of the target storage formation and possible degree of
filling with CO2
— if three-dimensional reservoir simulations are applied to estimate capacity, then the level of uncertainty
may be estimated by simulating a limited number of scenarios, including best-case and worst case
scenarios.
The level of uncertainty will also be reflected by the complexity of the method used to estimate capacity and
the reliability and resolution of the data from which the storage capacity has been estimated.
4.2.5.3 Reservoir injectivity
Early estimates of reservoir injectivity may be based on permeability measurements or calculations from
regional well-logs or production/injectivity data of existing wells in the injection zone. The uncertainty in
reservoir injectivity is often related to the availability of well-logs in the vicinity of the proposed storage site.
Other key uncertainty factors with regards to reservoir injectivity are the potential for compartments or flow
baffles in the target formation and the effect of near-well geochemical reactions that may limit the sustained
injectivity of a given well. These factors are, however, generally difficult to assess at the screening stage unless
the storage site has been subject to oil or gas development.
4.2.5.4 Containment
At the screening stage containment is typically assessed based on the formation type, depth, thickness, and
lateral extent of the primary seal above the target storage formation, as well as the density, depth, age, data
availability and drilling, construction and abandonment procedures for active and abandoned wells in the
region. Consideration should also be given to the potential for natural or induced seismic events to create
leakage pathways.
Key containment uncertainties relate to the degree and certainty of knowledge about these parameters and the
contribution from the four different trapping mechanisms (structural, capillary, solubility, and mineral
trapping) during the life cycle of the storage site. To evaluate the significance of the uncertainties, the
redundancies in the containment system (for example the presence of multiple geological seals and number of
independent well barriers) should be taken into account.
Guidance note:
Assessment of injectivity is also partly a commercial consideration since lack of reservoir injectivity can often be
managed by increasing the number of injection wells.
Depending on the availability of data, the assessment of the requirements defined in the Screening Basis may entail
acquisition of data not readily available (e.g., through drilling and collecting logs from an appraisal well) and
dedicated modelling efforts. The need for acquisition of additional data should balance the benefit of reducing
uncertainty against the cost of the data acquisition. Similarly the need for and scope of modelling efforts at this stage
should reflect the need for sufficiently robust assessments of capacity, injectivity and containment characteristics to
support the prioritization of storage sites for further characterization.
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4.2.6 Risk Assessment
The purpose of this step is to develop an initial risk register for each potential storage site within the context
of the preceding uncertainty assessment.
The initial risk register should be used for comparison in the following selection step and should be suitable for
independent audit and verification.
See Sec.6.3 for a risk assessment method description tailored to potential storage sites.
See Sec.7.3 for specific considerations with respect to existing wells.
This step represents the first risk assessment for the storage sites being screened and the resulting risk register
should form the basis for documenting the history of successive risk assessments. An electronic risk database
is recommended over a simple spreadsheet in order to keep track of changes over time and manage actions and
responsibilities related to individual risks or groups of risks.
The risk register should describe the methodologies and tools applied to assess and manage risks, define the
consequence categories and describe the risk evaluation criteria for each consequence category tuned to the
scope and objectives of the project. The risk evaluation criteria can entail the use of qualitative or quantitative
likelihood and consequence classes.
For each identified risk, the initial risk register should contain the following information from the risk
assessment:
—
—
—
—
a description of the potential causes and consequences of the risk
the estimated likelihood and severity of potential consequences before risk treatment
preferred risk controls
the estimated likelihood and severity of potential consequences after preferred risk controls are
implemented together with an explanation of the basis for the risk evaluation
— the names of the people assigned with responsibility to implement preferred risk controls
— the risk owner.
Revisions to the risk register should be documented in a transparent and traceable way. This includes
documenting the basis and rationale for revisions, the date that specific revisions were made, and by whom.
The risk register should also track the effect of implemented risk treatment, also when the effect is in
accordance with prior assessments of its effectiveness.
4.2.7 Milestone M2: Screening Report and Selection of Prospective Storage Sites
The purpose of this step is to select prospective storage sites from a ranked list of potential sites and document
the screening process in a Screening Report.
Each storage site should be evaluated against the requirements in the Screening Basis. The screening activities
should be evaluated against those described in the Screening Plan and the check-list in Table 4-2. The following
components should be collated in a Screening Report, which should highlight uncertainties and constraints that
might be put on injection at each storage site:
—
—
—
—
—
—
Screening Basis document
Screening Plan document
data collection and review findings
uncertainty assessment findings
risk assessment findings
evaluation against the requirements in the Screening Basis.
If the evaluations are positive for a storage site then it should be regarded as prospective and thereby qualified
for storage site appraisal.
If more than one storage site is prospective, the operator should take into account the results of the preceding
uncertainty and risk assessments in order to prioritise subsequent appraisal work.
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Risk
Geology and Environmental
Legal, regulatory, social and
commercial
Table 4-2 Screening check-list
Is the regulatory process and the requirements for CO2 geological storage in the target region
1
understood by the relevant competent personnel?
Have all applicable legal and regulatory constraints been identified, e.g., surface/subsurface access and
2 ownership, areas excluded from storage, trans-boundary issues and access for future field studies, such
as seismic surveys?
Have all social and cultural constraints that may impede the likelihood of project approval/acceptance
3 been identified and assessed, including public perceptions of CO2 geological storage and related issues
in the region?
4
Have all potential conflicts of use of the surface and subsurface at the target region been identified?
Have the sources, volumes and compositions of the CO2 streams to be injected and stored been
5
adequately defined?
6
Have opportunities for cost-effective transport from source to sink been adequately assessed?
Has the stratigraphy at each storage site been compiled and documented?
Have all potential storage reservoirs, primary seals and formations that may represent a conflict of
interest been identified? For example hydrocarbon or groundwater bearing formations.
7
Have structural and isopach maps of injection and confining zones been examined? For example
regional cross sections and tectonic maps.
Has the regional hydrogeology been studied?
Has sufficient data on the injection zone(s) been compiled and reviewed, including depth, thickness,
8
reservoir dip, lithology, pressure, temperature, porosity, permeability, salinity, mineralogy, interstitial
shale content and potential rock-fluid interactions?
Has sufficient data on each confining zone been compiled and reviewed, including depth, thickness,
9 areal extent, lithology, capillary pressure data, and other factors that may affect integrity of the
confining zone(s)?
Does the data reviewed on the confining zone(s) (for example fracture strength) provide adequate
10 confidence in the ability to ensure containment of injected CO2 streams to enable the decision to invest
in further storage site characterization?
Are the contributions from the four trapping mechanisms adequately understood at this stage of the
11 project?
12 Has storage capacity and injectivity of each potential storage site been estimated and the level of
uncertainty in these estimates been quantified?
Have all existing wells within each of the delineated areas for the potential storage sites been identified
13 and the corresponding well completion logs and well records been obtained?
14 Has the industrial history of the potential storage sites been reviewed, e.g., mining, groundwater
production, disposal of waste, natural and town gas storage, well abandonment history?
15 Have all environmental and economic receptors surrounding the potential storage site been identified?
Has relevant environmental data required for screening been acquired and reviewed, e.g., maps or
16 regional groundwater, surface water, sensitive terrestrial and marine ecosystems, and land use (for
onshore storage sites)?
Ability to monitor the storage site: has it been established that there are no obvious barriers to effective
17
monitoring?
18 Have all relevant consequence categories been defined?
19 Are the project specific risk evaluation criteria for the respective consequence categories appropriate?
Does the risk register comprehensively document how risks have been assessed for each element of
20 concern?
Is the basis and rationale for the evaluation of identified risks documented in a sufficiently transparent
21 way to support differentiation of potential storage sites based on legal, regulatory, technical,
commercial, social and cultural factors?
4.3 Appraisal
4.3.1 General
The purpose of this stage is to appraise prospective storage sites in detail and develop a well engineering
concept that provides the required capacity, injectivity and containment.
Appraisal should be carried out for a portfolio of prospective storage sites in order to minimise the risk of not
discovering a suitable storage site in a given area.
The storage site appraisal process shall provide an operator with enough technical information to determine
which storage sites remain prospective at Milestone M3 in Figure 2-1 and select the best candidate. The
appraisal process shall be documented in an Appraisal Report.
If successful, the appraisal process shall provide the information required to compile a robust Storage Permit
application.
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The following steps represent a generic recommendation of appraisal activities applicable to any region. The
scope of the steps is expected to vary between regions depending on the quality and quantity of existing data.
4.3.2 Appraisal Basis
The purpose of the Appraisal Basis is to provide a common set of requirements against which all prospective
storage sites will be assessed at Milestone M3.
The Appraisal Basis document shall include the requirements listed in Table 4-1 and Table 4-3 as a minimum:
Table 4-3 Requirements to prospective storage sites that shall be included in the Appraisal Basis (in addition
those listed in Table 4-1)
5) A requirement for a documented a) enable storage of required volumes of CO2
Well Engineering Concept that
b) enable storage at required rates of injection
shall:
c) provide long-term containment along new and existing wellbores
6) A requirement for documented evidence that sufficient baseline data can be acquired prior to start of CO2 injection
operations to enable differentiation of changes in environmental receptors attributable to CO2 injection from changes
attributable to pre-injection background variation or to natural or other anthropogenic sources
7) A requirement for documented evidence that surface and subsurface conditions shall allow implementation of
comprehensive and cost-effective monitoring capable of detecting possible deviations from planned operations
sufficiently early to allow for timely implementation of risk treatment
8) A requirement for evidence that a) risk management of the storage site during normal operations
simulation models exist that have
sufficient spatial and temporal
b) closure of the storage site following demonstration of conformance with
resolution to provide a basis for: monitoring observations
The Appraisal Basis document should also describe the context in which the appraisal activity is taking place.
The context may be described through any additional requirements to the appraisal process imposed by, for
example, the following:
—
—
—
—
—
—
—
the Storage Permit
drilling and well related permits
pipeline and surface infrastructure permits
the operator’s internal management processes
other commercial stakeholders in the storage site
independent verification
operators of subsurface developments above or below the injection zone, or of nearby subsurface
developments that may experience pressure communication originating from the planned storage operation
— emissions trading schemes in which the project wishes to participate
— financial investors
— local communities and landowners.
To ensure that the requirements imposed by any of the above are understood and properly accounted for in the
appraisal process, the operator should consult with representatives from each group of stakeholders that is
considered relevant for the Appraisal stage.
4.3.3 Appraisal Plan
4.3.3.1 General
The purpose of the Appraisal Plan is to describe the intended appraisal activities at each prospective storage
site, the scope of each of the following steps and the activities that the operator intends to carry out in each step.
The activities shall be appropriate for the type of data that will be used and the level of detail required for
comparison against the requirements set out in the Appraisal Basis. The Appraisal Plan shall include two
components:
— a Technical Appraisal Plan
— an Appraisal Communication Plan.
4.3.3.2 Technical Appraisal Plan
This document shall describe how storage site characterization and modelling activities will be performed for
each prospective storage site in order to provide the technical basis for the storage site and well engineering
concept selection.
The Technical Appraisal Plan shall take into account the knowledge gained during storage site screening and
include:
— a description of additional data needs in order to demonstrate compliance with the requirements in the
Appraisal Basis.
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— a description of how the additional data needs shall be met
— a description of how modelling studies shall provide an understanding of CO2 trapping mechanisms and
their interaction and reliability (for example structural trapping, residual CO2 (capillary) trapping,
solubility trapping and mineral trapping)
— a description of how the level of uncertainty attached to the requirements in the Appraisal Basis shall be
modelled and quantified through sensitivity studies or scenario analyses
— a description of how all relevant environmental receptors at each storage site shall be identified
— a description of how the environmental impact limits of the receptors will be determined with respect to
pressure dispersion and potential ingress by CO2 , dissolved solids or other displaced gas or fluid resulting
from the storage operations
— a description of how existing wells will be qualified, if present
— a description of the baseline monitoring data that will be collected and how this data provides a basis for
assessing storage site performance against the requirements in the Appraisal Basis
— a preliminary definition of the vertical and lateral boundaries of the storage complex and injection zone at
each prospective storage site.
Storage complex and injection zone definition
The purpose of defining the storage complex and injection zone in the Technical Appraisal Plan is to focus the
site characterization efforts, though it is recognized that these definitions may be modified in light of the site
characterization results.
Vertical boundaries shall be defined such that the storage complex includes, at least, the injection zone and the
primary seal. If economic or environmental receptors are present below the injection zone, then the storage
complex shall also include a zone below the injection zone that separates the injection zone from these
receptors.
Lateral boundaries shall be defined such that confidence can be established that the CO2 plume will be
contained within the storage complex throughout the project life cycle.
Guidance note:
An operator shall determine if execution of the Technical Appraisal Plan shall require exploration type permits for
conducting, for example, seismic data acquisition or drilling and well testing.
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Appraisal Communication Plan
The Appraisal Communication Plan shall describe how the operator intends to communicate with the relevant
stakeholders that influenced the requirements in the Appraisal Basis.
Executing the communication plan shall help an operator gain an understanding of any preferences the
regulator may have for which storage site to select.
The Appraisal Communication Plan shall:
— demonstrate that the operator has the ability and ambition to manage the selected storage site in a safe and
responsible way and in compliance with regulations
— describe the operator’s understanding of CO2 storage opportunities and risks in the region based on the
findings from storage site screening
— describe the requirements that the operator has included in the Appraisal Basis.
The Appraisal Communication Plan may define different communication goals for different stakeholders. For
example the last two bullet points above may only be relevant for the regulator.
Guidance note:
Stakeholder communication and consultation during storage site appraisal shall aim to provide interested parties with
objective, factual, relevant and understandable information about CCS in general and about the project in particular,
including the nature and degree of understanding of known or perceived risks. In particular, stakeholder
communication and consultation shall aim to ensure that stakeholder’s perceptions of risks and their values, attitudes,
needs, assumptions, and concerns that may impact storage site and injection concept selection are identified, recorded,
adequately understood and appropriately considered.
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4.3.4 Characterization
The purpose of this step is to perform the appraisal activities detailed in the Appraisal Plan in order to
characterize the storage sites with respect to the requirements in the Appraisal Basis.
This step represents the initial phase of storage site characterization, which shall be iteratively improved
throughout the life cycle of a storage site in order to support proper and continuous risk management. Unlike
the Data Collection and Review step during screening, this step may involve the acquisition and analysis of
new data in order to determine the relevant physical properties of a given storage site.
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Examples of the types of data that may be acquired and the information that may be derived from each are given
in Appendix A.
The operator shall produce a storage site Characterization Report that documents the following:
— the storage site characterization activities that have been carried out, a description of the data that has been
selected and of its quality, and the operator’s conclusions from this work
— that storage site characterization has been conducted in accordance with the principles listed in the
introduction to this section
— which storage sites remain prospective and why others may no longer be considered
— the resources (personnel and tools) applied to perform the storage site characterization activities, including
the expertise of the personnel involved
— the objective and nature of any consultation process with regulators or external stakeholders
— any natural or industrial analogues that have been used as references to underpin the suitability of a
prospective storage site, including any differences in the analogy that may lead to misinterpretation of the
analysis
— the storage site characterization is sufficient to support the storage site selection decision at Milestone M3
in Figure 2-1.
A synopsis of the Characterization Report should be made available to external stakeholders.
During the life cycle of a storage site the Characterization Report shall be updated as new data becomes
available and shall be reviewed for completeness and accuracy prior to or during successive risk assessments.
4.3.5 Modelling
4.3.5.1 General
The purpose of this step is to predict the future performance of a given storage site through numerical
modelling that shall simulate as closely as possible the physical processes relevant to CO2 storage.
Storage site modelling shall:
— be appropriate and relevant to the requirements in the Appraisal Basis
— provide information that supports risk analysis
— be fit for purpose in order to predict hydrodynamic, geochemical, thermal and geomechanical effects of the
CO2 injection and storage operations.
This step shall include the following activities:
— construction of a digital three-dimensional geological model (or a set of such models) for each prospective
storage site
— flow modelling using a set of digital three-dimensional numerical simulation models that are consistent with
the geological model(s) and suited to evaluate possible CO2 flow scenarios, effects of trapping
mechanisms, the pressure and temperature response over time, and the effectiveness of risk treatment
options
— geochemical modelling of potential geochemical effects on injection zone (capacity and injectivity),
primary seal (containment), and wells (well integrity and need for risk treatment)
— geomechanical modelling of pressure- or temperature-induced stress changes that can impact the integrity
of the primary seal or wells, the magnitude of ground surface deformation, and the potential frequency and
magnitude of any induced seismicity
— compilation of a storage site Modelling Report that includes a description of how the coupling between
models is handled. This description should address coupled flow and geomechanical effects on pressure
and temperature behaviour and geochemical alteration of porosity and permeability that may impact flow
and injectivity.
4.3.5.2 Geological model
The geological model(s) shall include a digital, three dimensional description of the following characteristics:
— overburden stratigraphy and hydrogeology including pressures and fluid compositions
— areal and vertical limits of all formations within storage complex, including, if applicable, the hydraulic
connected pore space within which the injection zone is located and pressure communication can be
measured
— existing wells that penetrate the storage complex
— economic or environmental receptors above and below storage complex
— structure of the physical trap (geometry of interface between the injection zone and the primary seal)
— geomechanical and geochemical properties of the injection zone and primary seal
— net porosity and permeability of all permeable geological formations within the storage complex
— geological faults or structural features in the storage complex that may represent a risk to long-term
containment.
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The geological model should have an appropriate spatial resolution to provide a basis for creating flow,
geochemical and geomechanical simulation models suited to capture the relevant physical processes and meet
their intents as outlined in Sections 4.3.5.3, 4.3.5.4, and 4.3.5.5 below.
Uncertainties associated with geological models shall be assessed. Focus shall be put on assessing uncertainty
related to features and parameters that have an impact on the requirements in the Appraisal Basis. When
assessing the uncertainty span, the operator shall identify and evaluate best-case and worst-case scenarios. The
operator shall also state what efforts will be made during eventual operation of a storage site to reduce the
uncertainty in the geological model further by calibrating parameters with observations.
4.3.5.3 Flow modelling
Flow modelling shall provide quantitative and auditable predictions of the following:
—
—
—
—
—
—
—
—
subsurface movement, extent and fate (trapping mechanism) of injected CO2 streams
subsurface movement and fate of formation fluids that will be displaced by CO2 injection
pressure build-up as a result of the CO2 injection and storage operation over time
evolution of temperature distribution in injection zone over time
effectiveness of secondary structural trapping and capillary and dissolution trapping
effectiveness of risk treatment options
parameter sensitivities (influence of parameter perturbations on predictions)
detection thresholds for monitoring measurements to enable timely implementation of risk treatment.
Flow modelling shall also provide a basis for the following:
— calibration of the geological model and CO2 flow parameters against observations (for example from
injection tests)
— design and evaluation of well engineering concepts (for example the number and type of wells, well
spacing, etc.)
— design and layout of monitoring and performance requirements for monitoring technologies (sensitivities
and spatial and temporal resolution and coverage).
Multiple numerical flow simulations shall be performed based on different geo-statistical representations of the
geology in order to allow estimation of variability of the key output parameters. The spatial and temporal
resolution of the simulation models shall be designed to reflect the reliability of the data, and to capture the
flow processes at spatial and temporal scales relevant for:
— demonstrating compliance with the requirements in the Appraisal Basis
— supporting risk analysis activities
— demonstrating the permanence of storage.
Guidance note:
It could give a misleading impression of the predictive ability of the model to perform high-resolution simulations if
there is substantial uncertainty in the geological description. The preferred resolution will, however, depend on the
capabilities of simulators available, and also on the resolution of the geological model.
A variety of simulators can be employed for numerical simulation of CO2 geological storage. In general, simulation
results shall be reproducible. However, different simulators may produce different results, depending on the physical
model (e.g., two-phase flow model or compositional flow model) and the numerical algorithms that are used in the
simulations. Thus, in order to allow verification of simulation results, the operator shall be ready to specify which
simulator has been employed and make all assumptions, variables and input data available.
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4.3.5.4 Geochemical modelling
The main objective of geochemical modelling for CO2 geological storage is to enhance the understanding of
potential geochemical effects on storage capacity, injectivity and containment. To this end, geochemical
models shall be built to provide insights into the chemical reactivity of the following components of the storage
site:
— the injection zone (for evaluation of potential effects on capacity and injectivity)
— primary seal (for evaluation of potential effects on containment)
— wells that may experience contact with CO2 or CO2-charged formation fluids (to evaluate the potential for
degradation of well integrity and the need for associated risk treatment).
— The geochemical modelling shall be performed for in-situ pressure and temperature conditions and account
for pressure and temperature changes predicted from flow modelling.
Guidance note:
The composition of the CO2 stream to be injected shall be defined by the operator prior to modelling geochemical
reactions.
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Sec.4 Storage Site Screening and Appraisal – Page 22
Chemical reactivity of the injection zone
Geochemical modelling of the injection zone shall be carried out and may assume that flow is transport
dominated and provide data related to:
— the initial geochemical characteristics of the injection zone at in-situ pressure and temperature
— effect of geochemical interactions (dehydration, dissolution and precipitation reactions) with the CO2
stream on storage capacity and injectivity
— change in formation fluid composition and phase behavior.
Chemical reactivity of the primary seal
Geochemical modelling of the primary seal shall be carried out and may assume diffusion dominated transport
in the matrix and flow dominated transport along discontinuities. The geochemical modelling of the primary
seal may provide information related to:
— the initial geochemical characteristics of the primary seal at in-situ pressure and temperature
— potential geochemical reactions (and extent of chemical reactivity) between the injected CO2 stream or a
CO2 charged formation fluid and the rocks and minerals in the primary seal
— the significance of geochemical reactions on the capacity of the primary seal to ensure long-term
containment.
Chemical reactivity of materials in wells
Analysis and geochemical modelling shall be performed for wells that may be exposed to CO2-saturated brine
or water-saturated CO2 to assess the potential impact of geochemical reactions on well material integrity. Wells
found prone to develop defects that present a significant risk to well integrity shall be studied further to
determine the need for priority monitoring and risk treatment. The process of assessing risk contributions from
wells and identifying appropriate risk treatment is further described in Sec.7.
4.3.5.5 Geomechanical modelling
The operator shall carry out geomechanical modelling to determine the potential for the following effects at a
given storage site:
— pressure- or temperature-induced stress changes to impact the integrity of the primary seal and the
significance of any potential geomechanical effects relative to long-term containment (for example
temperature induced stress changes around the injection wellbore)
— ground surface deformation (e.g., heave) and potential for induced seismicity as a result of CO2 injection
and storage operations and the respective significance relative to geomechanical stability.
In areas that have been subject to previous subsurface developments (oil and gas production, natural gas
storage, geothermal energy conversion, etc.) that may have induced stress effects on the storage complex, the
geomechanical modelling must also address historical pressure- and temperature induced stress changes as well
as changes predicted for the CO2 injection operations.
The geomechanical earth model to be used shall include, at least, a simplified representation of the overburden
and a more detailed representation of the storage complex.
The geometry of the geomechanical earth model shall be based on the spatial distribution of strata as
represented in the project’s geological model (see Sec.4.3.5.2).
The strata in the model shall be populated with the mechanical properties and in-situ stresses that shall have
been determined during the Site Characterization step.
4.3.5.6 Modelling Report
This report shall document the results of the modelling step and provide relevant input to the risk assessment
and Well Engineering Concept.
4.3.6 Risk Assessment
The purpose of this step is to assess the risks associated with each prospective storage site with respect to the
requirements in the Appraisal Basis and in light of the Site Characterization and modelling results.
The findings of this risk assessment shall be documented in an Appraisal Risk Assessment Report and recorded
in the project risk register that was recommended to be established during Storage Site Screening (Sec.1.5).
These findings shall be used to support decisions about the completeness of the Appraisal stage and the
qualification of prospective storage sites for Storage Permit application.
See Sec.6.3 for a risk assessment method description tailored to potential storage sites.
See Sec.7.3 for specific considerations with respect to existing wells.
The risk assessment criteria shall be consistent with the requirements in the Appraisal Basis such that
acceptability or tolerability of all risks indicates compliance with these requirements.
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Sec.4 Storage Site Screening and Appraisal – Page 23
4.3.7 Appraisal Review
The purpose of this step is to review the completeness of the Appraisal process and determine if the
characteristics of each storage site are adequately understood to support the qualification of one or more
storage sites for Storage Permit application. The findings shall be documented in an Appraisal review
document.
The operator shall assess if the level of understanding of each prospective storage site is sufficient to enable a
comprehensive evaluation of compliance with the Appraisal Basis requirements, and if so, carry out this
evaluation. These actions may lead to one of the following outcomes, which shall be documented in the
Appraisal review document:
— if the operator concludes that there is insufficient understanding of a given storage site, then further
characterization work, modelling and risk assessment shall be carried out until a sufficient level of
understanding is reached. The Appraisal Basis and Plan shall also be reviewed to determine if they are
appropriately defined and have been adequately executed for the storage site(s) in question
— if the operator concludes that there is sufficient understanding of a given storage site, but the evaluation
against the Appraisal Basis requirements is negative, then the storage site in question shall not qualify to
apply for a Storage Permit
— if the operator concludes that there is sufficient understanding of a given storage site and the evaluation
against the Appraisal Basis requirements is positive, then the storage site in question shall qualify to apply
for a Storage Permit.
If more than one prospective storage site qualifies for a Storage Permit application, then the operator may rank
these storage sites based on the findings of the preceding risk assessment. Such a ranking shall:
— include consideration of legal and regulatory compliance, cost, schedule, reputation, system performance
and public support even if these factors are not defined as consequence categories
— favour storage sites with natural inherent storage integrity higher than storage sites that require a larger
degree of engineering work to provide storage integrity
— use a consistent set of risk evaluation criteria. For example, the performance in terms of cost should take
into account both anticipated baseline costs (pipeline costs, drilling and construction costs, monitoring,
land access, etc.) and additional costs stemming from potential consequences of identified risks.
Ranking criteria shall be documented and the results may be summarized in a tabular format such as that shown
in Table 4-4.
Table 4-4 Example ranking of prospective storage sites based on risk assessment findings during
the Appraisal stage.
Consequence categories
Site 1
Site 2
Site 3
Site 4
HSE
1
4
2
3
Cost
3
2
1
4
Schedule
4
1
2
3
Storage Performance
1
4
3
2
Documenting the relative rank of sites in this manner is not necessarily suited for identifying a preferred storage
site, but may help detect higher risk storage sites. Tabulating relative ranks as illustrated in Table 4-4 may also
provide a good basis for discussing with the regulator and key stakeholders the rationale for selection of a
preferred storage site among a list of prospective ones that satisfy the selection requirements.
If one or more prospective storage sites are found to have significantly higher risks than others, then an operator
may decide to exclude these from the qualification process before studying potential well engineering concepts.
4.3.8 Well Engineering Concept
The purpose of this step is to identify the most appropriate well engineering solution for new and existing wells
at each prospective storage site at a conceptual design level.
An operator shall document a Well Engineering Concept that includes a description of the following:
—
—
—
—
—
—
—
—
the location and type of new wells required (for example; injectors, producers, monitoring wells)
the location and type of existing wells to be re-used
the location of abandoned wells
sub-surface trajectories
conceptual design of completions
approximate flow rates and total volumes for each injector
surface flow line geometry
pressure envelopes for each well.
For existing wells the operator shall:
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Sec.4 Storage Site Screening and Appraisal – Page 24
— specify which wells penetrate the storage complex
— specify which wells provide part of an identified leakage pathway
— specify which wells are predicted by reservoir modelling to be exposed to elevated pressure and the
pressure ranges
— specify which wells have the highest potential to leak
— specify the maximum CO2 volumes at risk of leakage from each such well
— specify which wells fall into the following categories:
—
—
—
—
active or suspended wells that do not require conversion for continued use
active or suspended wells that do require conversion for continued use
active or suspended wells to be plugged and abandoned prior to CO2 injection
wells previously plugged and abandoned
— provide an Initial Well Qualification Report for each well (see Sec.7.8).
In addition to down-hole considerations, the operator shall also describe the following:
— surface accessibility to well locations and corresponding required pipeline infrastructure
— scenario-based predictions of CO2 plume and pressure distribution during the life cycle of a given storage
site for a given well engineering concept
— cost predictions for the implementation and operation of a given well engineering concept
— cost predictions for construction and operation of required flowline infrastructure.
The last two bullet points above shall be considered when evaluating the economic feasibility of a storage site
and well engineering concept. The preceding bullet points shall be considered when evaluating the technical
feasibility.
If a technically and economically feasible well engineering concept cannot be identified for a given storage site,
then the storage site in question shall not qualify to apply for a Storage Permit.
4.3.9 Monitoring and Risk Management Planning
The purpose of this step is to determine if appropriate monitoring and risk management can be carried out at
a given storage site and maintained during the project life cycle.
Preliminary Monitoring and Risk Management Plans shall be developed for each prospective storage site for
which one or more technically and economically feasible well engineering concepts have been identified.
A preliminary Risk Management Plan shall:
— be designed to manage the risks identified and assessed in the preceding Risk Assessment step (Sec.2.5)
— include a preliminary risk treatment plan that shall describe how each identified risk can be controlled and
maintained at acceptable levels
— describe monitoring and modelling activities required to support risk management, including timely
implementation of risk treatment.
A preliminary Monitoring Plan shall:
— describe the purpose of monitoring during each project phase
— describe monitoring targets and technology performance requirements for each monitoring target
(sensitivity and spatial and temporal resolution and coverage)
— include the design (technologies and procedures), objectives (monitoring targets and associated technology
sensitivities) and layout (spatial and temporal resolution and coverage) of activities in a tentative base case
monitoring plan
— include the design, objectives and layout of a contingency monitoring plan designed to deal with situations
outside the envelope of expected system performance
— comply with the requirements for a Monitoring Plan described in Sec.5.4.7.
If the preliminary monitoring and risk management plans cannot provide confidence that all selection
requirements shall be met and maintained for a given storage site, then the storage site in question shall not
qualify to apply for a Storage Permit.
4.3.10 Milestone M3: Appraisal Report and Storage Site Selection
The purpose of this step is to evaluate which storage sites are qualified to apply for a Storage Permit and to
select one or more for further development. The appraisal process shall be documented in an Appraisal Report.
Storage sites and associated well engineering concepts that remain prospective shall be evaluated against the
requirements in the Appraisal Basis. In addition the appraisal activities should be evaluated against those
described in the Appraisal Plan. This evaluation process shall be documented in an auditable and transparent
manner by collating the following components in an Appraisal Report:
— Appraisal Basis document
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—
—
—
—
—
—
—
—
—
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Sec.4 Storage Site Screening and Appraisal – Page 25
Appraisal Plan document
Characterization Report
Modelling Report
Appraisal Risk Assessment Report
Appraisal review document
Well Engineering Concept document
Preliminary Risk Management Plan
Preliminary Monitoring Plan
Evaluation against the Appraisal Basis and Appraisal Plan.
If the evaluation is positive then the storage site in question shall be regarded as qualified to apply for a Storage
Permit.
If more than one storage site is qualified to apply for a Storage Permit, the operator may select one or more for
further development. This selection process shall take into account the results of the preceding evaluation and
the operator shall document the selection criteria used, the conclusions reached and the evidence that supports
those conclusions.
Prior to selection the operator shall provide the relevant regulator with an opportunity to comment on the
selection criteria to be used.
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Sec.5 Permitting – Page 26
5 Permitting
5.1 Introduction
This chapter describes a procedure for developing CO2 storage and closure permit applications. The term
storage permit is used generically in this chapter to cover the following:
— a new storage permit
— the renewal of an existing storage permit
— the transfer from one type of permit to another type (for example from enhanced oil production by CO2
injection to CO2 storage)
— the registration of a project in a regulated scheme that requires reporting of mass of CO2 emissions avoided.
This procedure addresses a number of common requirements that shall typically be met by an operator and a
number of generic documents that may vary in scope or name between jurisdictions.
Guidance note:
Exploration Permits are not described in this RP (for example to conduct seismic data acquisition or drilling and well
testing). This is due to variations in requirements between jurisdictions and the similarity to established practice in
hydrocarbon exploration.
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The operator shall carry out steps 1, 2, 3 and 5 from Figure 5-1 when applying for a CO2 storage or closure
permit. Step 4 should be carried out by the regulator or an entity acting on behalf of the regulator.
No
Step 1
Document
permit context
and requirements
Step 2
Define risk
performance targets
with regulator
Step 3
Develop or update
storage or closure
permit application
Step 4
Verify
completeness
Yes
Step 5
Submit
application
Figure 5-1
Procedure for developing CO2 storage and closure permit applications
5.2 Permit context and requirements (Step 1, Figure 5-1)
The operator shall describe the context and requirements, as defined below, in a permitting plan that also
describes how the operator intends to fulfil these requirements.
The context of the permit application shall be defined by documenting all of the following:
— the type of permit or application:
— a new storage permit
— the renewal of an existing storage permit
— the transfer from one type of permit to another type (for example from enhanced oil production to CO2
storage)
— the registration of a project in an regulated scheme that requires reporting of mass of CO2 emissions
avoided
— a closure permit.
—
—
—
—
the status of storage site characterization
the operational history of the site and any previous permits
the Risk Management context (see Sec.6.2)
the expectations from regulators and stakeholders to the permit application process.
Permit application requirements shall be defined by documenting all of the following:
— relevant regulatory requirements
— relevant requirements for reporting of mass of CO2 emissions avoided
— requirements imposed by the operator.
If the objective is to transfer from one type of permit to another type of permit, then the rationale for the need
or desire to change the regulatory status of the project shall be explained, and the differences in the respective
regulatory frameworks shall be highlighted.
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Sec.5 Permitting – Page 27
5.3 Risk performance targets (Step 2, Figure 5-1)
The operator shall specify acceptable risk performance targets for all significant risks (see Sec.6.4).
The specification of a risk performance target shall include:
— the target level of risk
— the risk treatment and/or inherent characteristics of a storage site that shall reduce and maintain the risk at
or below this level
— the expected and low-end likelihood that the specified risk treatment will be effective in meeting the target
level of risk
— the rationale and analysis behind the risk evaluation
Risk performance targets shall be relevant to the permit context and requirements described in the previous
step. Targets for storage operations shall be updated for storage site closure (see Table 5-2).
The following three stage process should be followed in order to reach agreement between the operator and the
regulator(s) about acceptable risk performance targets. Further iterations of this process may be required if
agreement is not forthcoming.
— operator proposes risk performance targets for a given storage site and well engineering concept
— operator documents additional or alternative risk treatment options that have not been selected and the
rationale for this decision
— operator and regulator discuss if target risk level is acceptable and if the prescribed risk treatment plan is
sufficiently robust with respect to targeted levels of risk. This may include consideration of the costeffectiveness and practicability of alternative risk treatment options relative to the proposed risk treatment
option.
Guidance note:
Quantitative risk assessments use quantitative criteria reflecting the likelihood of occurrence times the severity of
consequence (e.g., in terms of deaths per year) to determine the acceptability of risks. Such risk assessments require
sufficient relevant statistics or empirical data to enable a quantification of likelihood and consequence, which
generally will not be available for CO2 storage sites since each site will have its unique characteristics. The term “risk
performance target” should therefore be interpreted as a risk acceptance criterion in a qualitative sense.
For instance, the likelihood of loss of containment cannot generally be quantified based on available statistics or
empirical data, but can nevertheless be assessed and evaluated based on a careful examination of the geological
characteristics, the outputs from tailored modelling activities, and the way the site will be managed to control reservoir
pressure and CO2 plume migration. However, this evaluation will inevitably be associated with a certain degree of
uncertainty, as our knowledge of the subsurface is imperfect. Thus, to address this uncertainty and provide assurance
that the risk of loss of containment is sufficiently low, a site-specific risk treatment plan that accounts for all
reasonably likely eventualities must be developed, and its effectiveness assessed.
For this example, the risk treatment would typically entail the use of monitoring to provide early-warning signs, and
implementation of appropriate responses to avoid loss of containment. Hence, the likelihood of loss of containment
would be the likelihood that all natural (e.g., geological seals) and engineered (detection plus response) risk controls
fail.
Similarly, risk treatment plans should address ways to prevent adverse consequences if loss of containment occurs,
and to enable prediction of the severity of the consequences. Hence, while it may not be possible to put a number on
the initial risk of loss of containment, it is possible to qualitatively evaluate the effectiveness of a risk treatment plan
and use this evaluation to provide a high level of assurance that a risk performance target will be met.
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5.4 Storage Permit application (Step 3, Figure 5-1)
5.4.1 General
For Closure Permit application see Sec.5.5.
The application for a new Storage Permit should take the form of a Storage Development Plan, comparable to
a Plan for Development and Operations for hydrocarbon fields. The term Storage Development Plan is used in
a generic sense and DNV recognises that the name of this document and required content may vary depending
on jurisdiction. The recommendations given below are designed to fulfil all potential requirements.
The application for renewal of a storage permit, transfer of usage of a storage site or registration in a regulated
scheme that requires reporting of mass of CO2 emissions avoided, is expected to have a smaller scope than the
application for a new storage permit. For these cases the operator shall identify the relevant parts of this section
and use them as required.
A Storage Development Plan should include the following components:
1) a storage site Characterization Report
2) an Injection and Operating Plan
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3)
4)
5)
6)
7)
8)
9)
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Sec.5 Permitting – Page 28
an Environmental Statement
a Storage Performance Forecast
a Risk Management Plan
a Monitoring Plan
a Communication Plan
a storage site Closure Plan
an Accounting and Reporting Plan.
These components are described in the following sections.
Guidance note:
The Storage Development Plan can be a compilation of a set of documents that together contain the information
outlined in the subsections below, i.e., it is not required to be a single stand-alone document. In fact, some parts of the
Storage Development Plan may need to be submitted separately (e.g., the Environmental Statement), and some parts
will be frequently updated throughout the project, while others will typically be largely unchanged. This suggests that
the “Storage Development Plan” should be loosely interpreted as a compilation of various reports and plans that
combined provide the necessary technical information necessary for evaluating the eligibility of a project to achieve
a Storage Permit.
The content and structure of the Accounting and Reporting plan is not described because this is expected to be
prescribed by regulations and/or requirements of an emissions trading scheme.
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5.4.2 Characterization Report
See Sec.4.3.4.
5.4.3 Injection and Operating Plan
The Injection and Operating Plan shall be designed to meet the storage site performance requirements defined
in the Appraisal Basis (Sec.4.3.2). The plan shall include a final version of the Well Engineering Concept (see
Sec.4.3.8) and a Final Well Qualification Report for each existing well that is relevant to the storage site (see
Sec.7.12).
The Injection and Operating Plan shall also describe:
— expected injection forecast including variability in rate
— the expected variation in delivered well performance
— well operating procedures, including HSE procedures and contingency plans for shut-ins and well failures.
5.4.4 Environmental Statement
An Environmental Statement shall represent the outcome of an Environmental Impact Assessment or an
equivalent process required by environmental regulations. The operator shall review the relevant
environmental policy, legal and administrative framework within which the statement is prepared, including
all relevant regulations at a local, national and international level that could affect the storage site.
This step highlights some additional considerations with respect to a CO2 storage site that an operator shall
address:
— identify environmental receptors that may be affected by risks in the risk register for a given storage site,
for example:
—
—
—
—
—
—
air quality or marine environment (onshore/offshore)
soil or shallow sediments
surface water
groundwater
wetlands and floodplains
flora and fauna.
— identify the timescales required for restitution of local ecological resources
— describe the state of the environmental receptors prior to commencement of CO2 storage
— describe and predict possible environmental impacts of risks described in the risk register. Impacts shall be
specified in a quantitative, semi-quantitative or qualitative way with respect to frequency, duration and
magnitude
— define threshold values for degrees of impact significance for these receptors
— define relevant risk treatment and the modelling performed to assess the effectiveness of these measures
— describe monitoring targets and performance requirements for monitoring technologies (sensitivities and
spatial and temporal resolution and coverage) needed to ensure timely implementation of appropriate risk
treatment.
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5.4.5 Storage Performance Forecast
This document shall provide a scenario-based storage performance forecast that demonstrates the suitability of
the Injection and Operating Plan in meeting the storage site performance requirements defined in the Appraisal
Basis (Sec.4.3.2).
The operator shall carry out the following activities and describe the results in the Storage Performance
Forecast:
— identify the parameters from the Appraisal modelling step (Sec.4.3.5) that may influence the risks identified
in the Appraisal Risk Assessment step (Sec.4.3.6)
— perform sensitivity analyses of these modelling parameters
— model and predict base-case and high-end rates, cumulative volumes and timing of CO2 or displaced
formation fluids (including associated contaminants such as hydrocarbons or heavy metals) that may leak
from the storage complex and reach an environmental receptor as identified in the Environmental
Statement
— model and predict potential cumulative leakage of CO2 to atmosphere for each scenario that involves a
potential for leakage (CO2 escaping from the storage complex will be assumed to eventually enter the
atmosphere)
— describe risk treatment options to reduce the risk of environmental impacts and leakage to atmosphere
— define monitoring targets in terms of the following:
—
—
—
—
how they shall be used as indicators of a deviation from expected storage performance
their location
when and how the physical properties of the monitoring target may change
the required detection thresholds to enable timely implementation of risk treatment.
5.4.6 Risk Management Plan
The operator shall document how the risk management process described in Sec.6 shall be applied to a given
storage site in the Operate and Close stages of a project. The plan shall make reference to:
—
—
—
—
—
the storage site performance requirements defined in the Appraisal Basis (Sec.4.3.2)
the storage site risk register updated during the Appraisal Risk Assessment (Sec.4.3.6)
the environmental receptors described in the Environmental Statement (Sec.5.4.4)
the monitoring targets and risk treatment described in the Storage Performance Forecast (Sec.5.4.5)
the Monitoring Plan (Sec.5.4.7).
The risk management plan shall include a description of the following:
— the organizational procedures and practices to be applied to risk management, including assignment of
responsibilities
— the delegation of responsibilities, functions, and relationships among organizations and individuals to
ensure diligent and timely execution, monitoring and review of risk management activities
— a schedule for performing iterative risk assessments and activities supporting the risk assessments
— the consequence categories to be used
— risk evaluation criteria for each consequence category tuned to the scope and objectives of the project
— risk tolerability/acceptance thresholds
— risk treatment plans that describe how risks will be controlled and maintained at acceptable levels
— a robust contingency plan and associated costs for controlling a sufficiently broad range of conceivable but
unexpected circumstances that can represent a risk to consequence categories, including worst-case
scenarios
— how the monitoring plan is designed to support risk management activities
— how the site-specific modelling and simulation activities incorporate new monitoring results and is
designed to evaluate effects of uncertainties and support the risk analysis
— how the risk assessment methodology considers and accounts for uncertainty in site conditions and
processes that influence the performance of the storage site
— a plan for iterative review and revision of project risk register based on updated modelling and monitoring
results
— a schedule and process to map, monitor, review and document the risk management process
— a schedule and process for external communication/consultation with regards to risk management
— an impact hypothesis, including where and when any impacts may occur, and how any anticipated
consequences to consequence categories are weighed against the benefits of the project. The impact
hypothesis shall be formulated in a brief and concise way suitable for stakeholder communication.
Guidance note:
Risk treatment entails the process to implement risk controls to prevent, mitigate and correct situations that may cause
unwanted consequences, i.e., it encompasses the implementation of preventive, mitigative and corrective controls. All
of these types of measures should be adequately considered for each risk, and the combined effect of the prescribed
risk treatment should build confidence that risks will be controlled and maintained at acceptable or tolerable levels.
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Sec.5 Permitting – Page 30
The implementation of risk treatment should follow a three decision logic comprised of: (i) the detection of a
circumstance that signals the need to implement risk treatment; (ii) assessment and selection of an appropriate
treatment to address the situation; and, (iii) the implementation of the selected risk treatment. This procedure should
be followed by an assessment of the effect of the implemented risk treatment, whether the residual level of risk is
acceptable or tolerable, and, if not, an assessment and selection of additional risk treatment (see also Section 6.4).
It can be constructive to discuss risk tolerance/acceptability thresholds for key risks with regulators and stakeholders.
To this end, the operator may apply the ALARP principle (risks should be reduced as low as reasonably practicable)
as a structuring element for discussions to illuminate the paired concepts of (i) risk tolerance and (ii) practicability of
potential risk treatment (in terms of cost, time, effort, likelihood of success, and secondary risks potentially entailed
by the risk treatment).
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5.4.7 Monitoring Plan
5.4.7.1 General
The following steps represent a generic recommendation for developing a Monitoring Plan to be included in a
Storage Permit application.
Updates may be required for the renewal of a Storage Permit and shall be required for a Closure Permit
application (Sec.5.5). Such updates shall be obtained by iterating on each step of the process below while taking
new information into account.
5.4.7.2 Define objectives
The operator shall specify the monitoring objectives for a given storage site in the Monitoring Plan.
These objectives shall include:
— to monitor storage site performance in terms of health, safety and the environment in order to detect early
signs of potential impacts and maintain proper control of identified risks
— to verify predictive models and provide a basis for calibration and updating of models in order to enhance
capability to predict future performance
— to measure the quantity of CO2 stored at a site
— to locate and verify the containment of the injected CO2 within the storage complex.
Site specific objectives shall also be added as appropriate.
5.4.7.3 Describe context
The operator shall establish the context for a Monitoring Plan in order to demonstrate that the plan fulfils:
— regulatory requirements
— emissions trading requirements (if applicable)
— international precedents set by other CO2 storage sites.
The context shall be established by identifying regulations and precedents that are relevant to a given project
and documenting why others may not be. For example, monitoring activities carried out by other projects for
research purposes may not be proven or suitable.
5.4.7.4 Specify monitoring targets
The operator shall re-iterate the monitoring targets specified in the following two documents:
— the Environmental Statement (Sec.5.4.4)
— the Storage Performance Forecast (Sec.5.4.5)
These monitoring targets shall have been identified by the Risk Assessment that was carried out during the
Appraisal stage (Sec.4.3.6). The method for identifying monitoring targets is described in Sec.6.3.3 (Risk
Analysis).
For each monitoring target the operator shall specify:
—
—
—
—
—
the physical property to be measured
the location(s) at which the physical property shall be measured
the frequency or time intervals at which the physical property shall be measured
the natural variability of physical property (temporal and spatial)
the detection thresholds required to satisfy the specified monitoring objectives (for example, protection of
other operator’s hydrocarbon and mineral rights, groundwater, sensitive flora and fauna within the
biosphere/marine biosphere and leakage to atmosphere).
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5.4.7.5 Screen monitoring techniques
There exist a large number of monitoring techniques that can be applied to CO2 storage sites, but not all will
be technically feasible for any given site. This will be determined by, amongst other factors:
—
—
—
—
—
—
the location (onshore/offshore)
the terrain and land use (onshore)
water depth and seafloor conditions (offshore)
the depth of the injection zone
the lithology of the storage complex and overburden
the sensitivity and reliability of a given technique.
The operator shall identify the techniques that are technically feasible at a given site and document the
techniques that were found to be technically inappropriate. This will demonstrate to a regulator the full list of
techniques that was considered.
Guidance note:
A best practice manual for monitoring, verification and accounting of CO2 stored in deep geologic formations has
been developed by the U.S. Department of Energy National Energy Technology laboratory. This reference contains
a comprehensive list of potential monitoring techniques that may be applied:
U.S. Department of Energy National Energy Technology Laboratory, Best Practices for: Monitoring, Verification
and Accounting of CO2 stored in Deep Geologic Formations, (2009).
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5.4.7.6 Select monitoring techniques
While all of the feasible techniques could be applied to the site in question, this does not mean to say that they
should be. The usefulness of the data generated by the techniques will differ, as will their cost of deployment
and environmental impact.
The operator should apply and document a qualitative cost-benefit analysis in order to rank the techniques
according to the information benefit they bring to the project, bearing in mind the performance targets that have
been set. For example, the techniques may fall into one of the following four categories:
— high benefit and low cost – should be selected and may be used more frequently
— high benefit and high cost – should be selected, but may be limited to focused applications and used less
frequently
— low benefit and low cost – may be selected
— low benefit and high cost – should not be selected.
The rationale for the operator’s selection shall be documented and techniques that have been dismissed due to
lack of technical feasibility, inadequate sensitivity/reliability or low benefit relative to cost shall be documented
together with their reasons for rejection.
5.4.7.7 Plan monitoring activities
The operator shall describe the following in the Monitoring Plan:
— procedures for documenting monitoring activities, procedures and results
— the schedule and process for reviewing, updating and documenting changes to the monitoring plan to adapt
to changes in objectives or circumstances or to incorporate lessons learnt or changes to best practices
— the baseline against which monitoring measurements will be compared, which shall include observed and
expected temporal trends and fluctuations
— the design (technologies and procedures), objectives (monitoring targets and associated technology
sensitivities) and layout (spatial and temporal resolution and coverage) of activities in base case monitoring
plan
— the assumptions and expected conditions (base case scenario) for which the monitoring plan is designed
— the design, layout and objectives of a contingency monitoring plan designed to deal with situations outside the
envelope of expected system performance, which may include additional monitoring to design and evaluate
risk treatment, and possibly the establishment of a consultation panel of independent qualified experts.
5.4.7.8 Evaluate completeness
The purpose of this step is to check that the Monitoring Plan is complete, fit for purpose and in compliance with
regulations. The operator may employ an external party to perform this step in order to obtain an unbiased
viewpoint.
The operator or external party shall perform the following activities:
— check the status of the permit application with respect to the objectives defined in Sec.5.4.7.1
— check compliance with relevant regulations (may take the form of a dialogue with the regulator)
— check compliance with relevant standards, codes or guidelines
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— conduct further technical studies to quantify particular aspects of the qualitative cost-benefit analysis in the
previous step, if required
— check the fitness-for-purpose of the Monitoring Plan according to the requirements in Table 5-1.
Table 5-1 Requirements for the Monitoring Plan
Designed to monitor storage site performance in terms of health, safety and the environment in order to detect early signs
1 of potential impacts and maintain proper control of identified risks.
2
3
4
5
6
7
8
9
Designed to verify predictive models and provide a basis for calibration and updating of models in order to enhance
capability to predict future performance.
Designed to verify the mass of CO2 stored.
Designed to demonstrate requirements for site closure, if applicable.
Designed to provide regulators and stakeholders with confidence that the storage site is adequately understood and
remains suitable for CO2 geological storage.
Designed to identify trends that may lead to deviations in site performance beyond agreed limits sufficiently early
(accepted by the operator and the regulator) to allow either:
— timely implementation of appropriate changes to the Site Development Plan
— timely and safe shut-down of CO2 injection.
Includes procedures for the Monitoring Plan to be periodically reviewed and revised as needed to support proactive risk management and adapt to changing project circumstances and advances in technology or best practices.
Allocates responsibility and accountability for timely and diligent execution of the monitoring activities.
Includes procedures for evaluating the monitoring activities and processes against defined performance
requirements.
5.4.8 Communication Plan
The operator shall develop a Communication Plan for responding to significant events. The plan shall be
designed to facilitate understanding among internal and external stakeholders of the nature of the risks posed
by the event, including its possible causes, their potential consequences and risk treatment.
The plan shall describe when and how the operator will carry out the following actions:
—
—
—
—
communicate to regulators, stakeholders and the public that a significant event has taken place
provide information about risk treatment
communicate impact on the environment and/or economic resources, if any
evaluate the effectiveness of the communication.
5.4.9 Closure Plan
The operator shall develop a storage site Closure Plan that describes closure requirements for a given storage
site and the qualification process that shall be used to demonstrate fulfillment of these requirements.
In addition, the operator shall include a plan for long-term stewardship in the Closure Plan that includes the
following components:
— plans for monitoring activities (design, layout and objectives), as required by applicable regulation, to
detect signs of leakage at the surface or in subsurface environmental or economic receptors
— a description of risk treatment to address the most likely events identified from the closure qualification
process, which shall include fluid migration (CO2 or otherwise) via wells
— plans to notify future land and resource owners of the storage site and remaining subsurface infrastructure
— a description of the entity responsible for undertaking the long-term stewardship plan.
5.5 Closure Permit application (alternative Step 3, Figure 5-1)
5.5.1 General
The application for a Closure Permit, if applicable, should take the form of a Closure Qualification Statement
that includes the following components:
—
—
—
—
—
a description of the Closure Basis
an Environmental Statement for storage site closure
a Storage Performance Forecast for storage site closure
a Monitoring Plan for storage site closure
an Updated Closure Plan.
These components are described in the following sections and represent the output of a qualification process
for storage site closure.
This qualification process shall be carried out by the operator in order to provide sufficient evidence that a
given site shall fulfil the closure requirements. The process shall follow a structured and transparent approach
aiming to show how the operator has managed risks within acceptable levels during the project.
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The qualification process may be initiated when the operator has concluded, based on a preliminary assessment,
that the requirements for site closure according to applicable regulations have been met.
5.5.2 Closure Basis
The Closure Basis shall include a list of requirements that shall be fulfilled in order for the storage site to be
closed. These requirements shall include, at least, the requirements listed in Table 5-2.
Table 5-2 Requirements for storage site closure
1) A requirement for documented a) actual storage performance during the injection phase of the project has been
evidence that the storage site is
consistent with the initial and updated Storage Performance Forecasts
sufficiently understood to predict b) actual storage performance after the cessation of injection has been consistent
its future performance:
with the updated Storage Performance Forecasts.
2) Further risk treatment is not required.
3) All wells that penetrate the storage complex have adequate well integrity.
4) Assurance of long-term containment can be maintained by observation of a limited number of key monitoring targets.
The Closure Basis document should also describe the context in which the closure qualification activity is
taking place. The context may be described through any additional requirements to the closure qualification
process imposed by, for example, the following:
—
—
—
—
—
—
—
—
the Storage Permit
the Closure Permit
surface infrastructure decommissioning regulations
well abandonment regulations
the operator’s internal management processes
other commercial stakeholders in the storage site
independent verification
operators of subsurface developments above or below the injection zone, or of nearby subsurface
developments that may experience pressure communication originating from the planned storage operation
— emissions trading schemes in which the project wishes to participate
— financial investors
— local communities and landowners.
To ensure that the requirements imposed by any of the above are understood and properly accounted for in the
closure qualification process, the operator should consult with representatives from relevant stakeholders.
5.5.3 Environmental Statement for storage site closure
The operator shall update the Environmental Statement from Sec.5.4.4 with respect to:
— any natural changes to the storage site and surrounding environment
— any man-made changes to the storage site and surrounding environment (not related to the CO2 storage
activities)
— any changes to the storage site and surrounding environment resulting from the CO2 storage activities
— any changes to environmental monitoring targets or their threshold values
— any changes to environmental regulations
— potential impacts from storage site decommissioning.
5.5.4 Storage Performance Forecast for storage site closure
The operator shall update the Storage Performance Forecast from Sec.5.4.5 with respect to historical
performance data. This step shall help fulfil the following closure requirements:
— provide the evidence that the storage site is well understood and that performance can be predicted after
closure (Requirement 1 in Table 5-1)
— define a limited number of key monitoring targets that may be used to provide assurance of long-term
containment (Requirement 4 in Table 5-1).
Relevant historical data that shall be compiled during this step includes:
— operational logs that document the history of storage site operations
— monitoring logs that document and map the history of the monitoring and verification activities
— an updated risk register documenting how risks have been assessed and managed throughout the life cycle
of the storage site, including description of reasons for upgrading or downgrading risks during the life cycle
of the storage site
— description of how key uncertainties have been analyzed and managed throughout the life cycle of the
storage site, and review of key decisions made in light of these uncertainties
— compilation of risk performance targets, including a record of changes made during the life cycle of the
storage site and a description of the reasons for these changes
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— compilation of results and conclusions drawn from monitoring, modelling and risk assessments to support
demonstration of compliance with site closure requirements, including description of how geomechanical
and flow simulation models have been calibrated or adjusted
— historical storage performance relative to predictions from modelling and simulation.
Consistency of actual and predicted storage performance shall be demonstrated by:
— a converging trend between the comparisons over time
— model calibrations by history matching no longer alter the understanding of the storage site characteristics
in a way that significantly influences the performance predictions
— the uncertainty band on the predictions of CO2 plume migration and pressure development is within
acceptable limits.
5.5.5 Monitoring Plan for storage site closure
The operator shall update the Monitoring Plan (Sec.5.4.7) with respect to the revised list of key monitoring
targets defined in the updated Storage Performance Forecast (Sec.5.5.1.4).
5.5.6 Updated Closure Plan
The operator shall update the Closure Plan from Sec.5.4.9 with respect to:
—
—
—
—
any updates to the closure requirements
the revised list of key monitoring targets defined in the updated Storage Performance Forecast (Sec.5.4.5)
any updates to risk treatment due to advances in technology
any changes to stakeholder composition (for example by change of land ownership).
5.6 Evaluate completeness (Step 4, Figure 5-1)
The purpose of this step is to check that the permit application is complete, fit for purpose and in compliance
with regulations. The operator should perform the following activities:
—
—
—
—
check the status of the permit application with respect to the requirements described in Step 1 (Sec.5.2)
check compliance with relevant regulations
check compliance with relevant standards, codes or guidelines
check the fitness-for-purpose of the permit application.
In the case that the permit application is a Storage Development Plan, then the requirements in Table 5-3 shall
be used to check its fitness-for-purpose.
Table 5-3 Requirements for a Storage Development Plan
1 Storage Development Plan is tailored to the unique characteristics of the storage site.
The Characterization Report provides a sufficiently detailed and reliable description of the storage site to
2 demonstrate and confirm the suitability of the storage site for environmentally safe long-term CO2 geological
storage.
The Injection and Operating Plan documents the technical and economic feasibility of the CO2 injection
3
operations.
The Environmental Statement describes all potential consequences to environmental receptors that may stem from
4 the risks in the risk register, and documents the analysis that is used to determine impact significance thresholds
for these receptors.
The results of predictive modelling that are documented in the Storage Performance Forecast are based on the
5 Injection and Operating Plan.
6 The Storage Performance Forecast provides sufficient understanding of containment and performance risks to
form a robust basis for design of the Monitoring and Risk Management Plans.
The predictive models used by the operator are capable of demonstrating adequate conformance with observations
7
to sustain CO2 injection operations (support renewal of storage permit) and allow for timely site closure.
8 The Risk Management Plan is suitable for the storage site and will ensure that risks are appropriately managed.
The Monitoring Plan gives assurance that risks can be controlled at “acceptable” levels (see requirements in Table
9 5-1).
Communication Plan is appropriate to the level of knowledge about CO2 geological storage in general and the
10 The
CCS project in particular among relevant stakeholders, and is suited to address the concerns that may arise.
5.7 Submit application (Step 5, Figure 5-1)
The operator should submit the application in question according to the requirements specified in Step 1
(Sec.5.2).
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6 Risk management
6.1 Introduction
The purpose of risk management is to ensure that opportunities and risks related to the geological storage of
CO2 at a given site are effectively managed in an accurate, balanced, transparent and traceable way. The
recommended risk management process is modified from ISO 31000 to take account of specific considerations
for CO2 geological storage and is illustrated in Figure 6-1.
Establish
context
Assess risks:
• Identify
• Analyze
• Evaluate
Plan and
assess risk
treatment
Iterate &
calibrate
Monitor, review and document
Figure 6-1
Recommended risk management process for CO2 geological storage.
This process is designed to:
—
—
—
—
—
run in parallel with the project life cycle stages in Figure 2-1
provide CO2 storage operators with decision support at key project milestones
reduce cost and schedule risks during storage site Screening and Appraisal
improve storage performance during the Operate stage
increase the likelihood of obtaining Storage and Closure Permits in a timely manner.
The process steps shown in Figure 6-1 are described below.
6.2 Risk management context
6.2.1 General
The operator shall establish the context of their risk management process by:
—
—
—
—
—
—
defining the project objectives (Sec.6.2.2)
defining the responsibilities for and within the risk management process
defining the scope of the risk management process (Sec.6.2.3)
identifying and specifying the decisions that have to be made
defining the consequence categories to be used (Sec.6.2.4)
defining the risk evaluation criteria to be used (Sec.6.2.5).
6.2.2 Project objectives
The operator shall define objectives for the project in question that are aligned with organisational goals.
Whereas goals may be high level statements that provide an overall context for what the operator is trying to
achieve, the objectives shall describe the specific, tangible results that a given project will deliver.
Project objectives shall be specific, measurable, achievable, realistic and time limited.
6.2.3 Scope
Table 6-1 describes internal and external factors that an operator shall take into account when defining the
scope of the risk management process.
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Operator and
project resources
Legal, regulatory, Social, cultural,
Environment, resources,
and industry
political and
infrastructure and subsurface
practice
economical
developments
Table 6-1 Internal and external factors affecting the risk management context.
1 Natural environment: meteorology, surface/marine environment (ecology, wildlife, botanic, parks
and reserves, etc.), biosphere, hydrosphere, and geosphere (including geology, hydrogeology,
geochemistry, tectonics and seismicity).
2 Resources: groundwater, hydrocarbon and mineral reserves, coal seams, geothermal energy.
3 Infrastructure and facilities: buildings, transportation corridors (roads, railroads, pipelines, etc.),
power distribution lines, oil and gas production and processing facilities, wells, groundwater
reservoirs.
4 Subsurface developments: hydrocarbon production, mineral extraction, mining, waste disposal,
natural gas storage, acid gas disposal, geothermal energy conversion.
5
6
7
Demographic, historical and cultural factors that can influence how the project will affect or be
viewed by stakeholders.
Political elements and trends that may influence the perception and/or financing of a storage site.
Geographic and temporal economic factors, including possible effects of the project upon the local
economy.
8
Relevant directives, acts and regulations applicable to storage sites and any active initiatives to
introduce new or modify existing directives, acts or regulations.
9 Relevant codes, standards, protocols and guidelines that may serve to guide risk management and
facilitate demonstration of compliance with regulations, acts and directives.
10 Manuals that document current industry practice and guide cost-effective implementation of CO2
storage technology and in accordance with best industry practice.
11 Economic ownership, contributions and liabilities for each component in the CCS system.
12 Operator’s responsibility and authority limitation, including its resources and commitment to risk
management.
13 Experience of the organizations involved in the project to address risks through the development and
implementation of a comprehensive risk management plan.
14 Available resources, capacities and capabilities for performing isolated functions with respect to the
storage site and for integration across all project components in the project and in the total CCS
system.
6.2.4 Consequence categories
Risks may be usefully grouped into categories according to the nature of their consequences. The consequence
categories for risk management of a CO2 storage site shall include the following:
—
—
—
—
human health and safety
environmental protection
storage site containment
storage site performance.
The consequence categories should also include the following:
—
—
—
—
legal and regulatory compliance
cost
schedule
reputation.
An operator may use additional categories as appropriate.
Stakeholder views and risk perceptions shall be adequately understood and appropriately considered when
specifying consequence categories. To this end, stakeholders’ values, assumptions, capabilities, and concerns
that may impact decisions based on risk considerations or hinder the achievement of objectives shall be
identified and recorded.
6.2.5 Risk evaluation criteria
The operator shall define risk evaluation criteria to be used to evaluate the significance of risk. The criteria shall
be aligned with the project objectives and may be derived from regulations, standards, recommended practices
or other requirements.
The operator shall consider the following factors when defining risk evaluation criteria for a CO2 storage site:
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— the distinction between risks to performance and containment (commercial versus environmental criteria
for example)
— the timeframe of reference for a given risk (different for operational and post-closure risks, amongst others)
— how likelihood may be defined (qualitatively or quantitatively as a probability or frequency)
— the views of stakeholders (for example commercial partners)
— how combinations of multiple risks may be linked together to create risk scenarios (for example leakage of
formation fluids to surface along an abandoned well).
— the level at which a given risk becomes acceptable or tolerable (for example the frequency values that
correspond to the three regions in Figure 6-2).
The level of a risk may be unacceptable, tolerable or broadly acceptable:
— unacceptable – risks cannot be justified except in extraordinary circumstances
— tolerable or as low as reasonably practicable (ALARP) – risks are tolerable if further risk reduction is
impracticable or the costs of additional risk reducing measures are disproportionate to the improvement
gained;
— broadly acceptable – no need for detailed effort to demonstrate that risks are reduced ALARP.
These levels are illustrated in Figure 6-2.
Risks cannot be justified
except in extraordinary
circumstances
Unacceptable
Region
Tolerable or
ALARP Region
Tolerable only if risk
reduction is impracticable
or if the cost is grossly
disproportionate to the
improvement gained
Broadly Acceptable
or Negligible Region
No need for detailed effort
to demonstrate ALARP
Figure 6-2
Levels of risk that should be used to establish risk evaluation criteria
6.3 Risk Assessment
6.3.1 General
The operator shall assess risks using the three stage approach described below.
6.3.2 Risk identification
The operator shall perform a comprehensive risk identification process that considers all relevant risks, and
documents in a transparent, traceable and consistent manner which threats, events and consequences have been
considered.
The risk identification process shall be tailored to the relevant stage of development for a project, for example
Screening risk assessment (Sec.4.2.6) or Appraisal risk assessment (Sec.4.3.6).
The following activities shall be performed:
— identification of threats to the consequence categories established in the risk management context
(Sec.6.2.4).
— identification of additional threats related to novel aspects of the project, for example:
— unique features of the storage site under consideration
— technical or organisational aspects that are outside the operator’s experience.
— identification and description of risk scenarios for each threat containing:
— one or more threat-event scenarios
— one or more event-consequence scenarios.
— comparison of identified risk scenarios with an acknowledged database of threats, events and consequences
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— description of environmental and economic receptors that may be negatively impacted by potential loss of
containment or geomechanical responses to the CO2 injection and storage operations.
— identification of interdependencies between different risk scenarios, including potential for cascading
effects that may increase likelihood of occurrence or severity of consequences.
6.3.3 Risk Analysis
Risk analysis aims to enhance the understanding of risks, including the nature of the risk itself, the likelihood
of occurrence and the severity of potential consequences to the relevant consequence categories for each risk.
The risk analysis shall:
— be technically defensible and based on best available knowledge or scientific reasoning
— assess the span of possible system performance scenarios, and evaluate risk treatment options
— provide the technical basis for evaluating risks, and, whenever practically feasible, assess and quantify the
degree of uncertainty in the level of risk.
Where sufficient and demonstrably relevant data can be obtained, quantification of likelihood and consequence
shall be based on appropriate scientific reasoning or auditable statistics and/or calculations. Otherwise,
quantification shall be based upon the documented judgment of experts who are qualified in terms of applicable
professional expertise and project knowledge.
Care shall be exercised to ensure that the results of the risk evaluation exhibit reasonable accuracy. If
significant uncertainty related to risk magnitude exists, relative to the risk evaluation criteria, then the degree
of uncertainty shall be modelled through sensitivity studies or scenario analyses and be used to provide
reasonable uncertainty bands.
Guidance note:
The operator shall distinguish between the following two broad categories of uncertainty that are relevant to
geological storage sites:
— uncertainty associated with the description of the storage site including the site characteristics, engineered
components, and natural processes and their interaction with the environment
— the degree to which the conceptual and mathematical models are representative of the actual system.
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The operator shall document in a transparent, traceable and consistent manner how each of the following
activities has been performed in the risk analysis process:
— analysis of likelihood of occurrence for each identified risk scenario
— analysis of severity of potential consequences to the consequence categories for each identified risk
scenario
— analysis of uncertainty in the likelihood of occurrence and severity of potential consequences for each risk
scenario
— identification of measures to reduce or manage uncertainty that can influence the risk evaluation and/or
selection of risk treatment, and assessment of the effectiveness of these measures
— identification and visualization of risk controls in an event-focused way:
— preventive controls that may be applied to threat-event scenarios
— mitigative controls (including corrective controls) that may be applied to event-consequence scenarios
(see Figure 6-3 for an example)
— assessment of the uncertainty associated with the effectiveness of risk controls
— identification of monitoring targets and performance requirements for monitoring technologies
(sensitivities and spatial and temporal resolution and coverage) required for timely implementation of
appropriate risk treatment
— identification of data requirements and modelling and simulation studies to be performed to support the risk
analysis
— analysis of cumulative likelihood that the respective risk events may occur
— analysis of cumulative likelihood that significant negative impact to the respective consequence categories
may occur.
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Active
control 2
Active
control 1
Passive
control 2
Passive
control 1
Threat
Threat –Event Scenario
Event
o
enari
ce Sc
n
e
u
seq
t–Con
Even
Consequence 1
Event–Consequence Scenario
Consequence 2
Even
t–C
Preventive controls
onse
q
uenc
e Sc
enari
o
Consequence 3
Mitigative controls
Figure 6-3
Example of risk control visualisation that may be used to support risk analysis
6.3.4 Risk evaluation
The purpose of risk evaluation is to use the outcome of risk analysis to assist in making decisions about which
risks need treatment and their order of priority.
Risk evaluation determines the significance and tolerability/acceptability of risks and sets the performance
requirements for risk treatment. The planning of risk treatment actions is described in Sec.6.4.
The operator shall document in a transparent, traceable and consistent manner how each of the following
activities has been performed for each risk in the project risk register:
—
—
—
—
identification of risks that require treatment based on the results of risk analysis
prioritization of these risks
documentation of the level of risk prior to risk treatment
specification of the target risk levels to be achieved by risk treatment.
6.4 Risk treatment
Risk treatment involves selecting one or more options for modifying risks and implementing those options.
The operator shall develop a risk treatment plan for the relevant risks that were identified and prioritized during
risk evaluation. This plan shall document in a transparent, traceable and consistent manner how each of the
following activities has been performed for a selected risk:
— identification of the risk treatment options that are
— cost-effective
— do not introduce other significant risks that outweigh potential benefits of the treatment
— evaluation of the following risk treatment options in order of preference:
—
—
—
—
—
—
avoid risk
remove threat
reduce likelihood
reduce consequences
share the risk with another party or parties
retain and tolerate the risk by informed decision
— prioritization of risk treatment options, including the order in which risk controls shall be implemented
— specification of risk performance targets for all significant risks including:
— target risk levels
— planned risk treatment to control and maintain the risk at or below this level
— evaluation of uncertainty attached to risk levels, both pre-mitigation and post-mitigation:
— in the case that significant uncertainty exists, the operator shall explain how uncertainty is taken into
account and defend why the risk treatment plan is robust with respect to targeted risk levels
— planning of contingency measures for managing conceivable, but unexpected circumstances or incidents
that carry risks or give rise to negative impacts to consequence categories.
Following implementation of risk treatment the operator shall evaluate the level of risk in order to determine
if a given risk performance target has been met (see Sec.6.5).
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Risk treatment plans shall be reviewed and revised as required in order to ensure that risks remain acceptable
throughout the life cycle of the storage site.
6.5 Risk management review and documentation
6.5.1 General
The risk assessment results shall be revisited as required to ensure that changes in the context for risk
management are detected in a timely manner, and that the risk management plan continues to be suitable for
the storage site.
Reviews of the risk management process shall be executed on a regular basis and documented in a transparent
and traceable manner throughout the life cycle of a storage site. The responsibilities for monitoring and review
shall be clearly defined.
6.5.2 Process
The monitoring and review of the risk management process shall evaluate compliance with the following
requirements:
—
—
—
—
risk controls are effective and efficient, and implemented as needed in a timely manner
data is gathered as needed to improve risk assessment and management
lessons learnt from successes and failures are documented and analysed
changes in the context are detected in a timely manner, including changes to consequence categories, risk
evaluation criteria and the risk itself which can require revision of risk treatments and priorities
— emerging risks are identified in a timely manner
— progress in implementing risk treatment plans is measured against risk performance targets
— the results of monitoring and review are recorded and externally and internally reported as appropriate and
are used as an input to the review of the risk management plan.
6.5.3 Transparency
The risk evaluation criteria for each consequence category shall be documented. For all consequence categories
other than those that involve strictly the operator’s interests, the risk acceptability/tolerance thresholds shall be
specified. For consequence categories that involve strictly the operator’s interests, these thresholds should be
specified.
The operator shall document and describe monitoring and modelling outputs that form a basis for the risk
assessments, the assumptions and references for the modelling studies, and implications of monitoring
technology limitations on the risk assessment results.
6.5.4 Traceability
The results of risk assessments shall be recorded in a consistent manner so that risk assessments are comparable
over time. The risk owners shall be documented. Changes in assumptions and design of modelling and
monitoring plans shall be documented and justified. If different risk assessment methodologies have been
applied, it shall be demonstrated how the results of updated assessments compare with the most recent
assessment. If the results of an updated risk assessment deviate significantly from the prior assessment, the
reasons for the differences shall be documented.
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7 Well qualification
7.1 Introduction
Well Qualification, in the context of this RP, refers to the process of providing the evidence that a given well
will function within specific limits with an acceptable level of confidence when exposed to the effects of CO2
storage. The operator shall apply this process to:
— plugged and abandoned wells that shall continue to provide formation fluid containment
— active or suspended wells that shall be plugged and abandoned prior to CO2 storage operations
— active wells that shall retain their original function during CO2 storage operations before final plugging and
abandonment
— active wells that shall have a modified function during CO2 storage operations before final plugging and
abandonment.
In addition the operator may apply this process to the design of new wells.
The current status of existing wells that may be exposed to the effects of CO2 storage shall have been
established during the Screening and Appraisal stage risk assessments. The task of well qualification is then to:
— identify risks to the future performance and reliability of a given well (failure modes and mechanisms)
— reduce these risks in a systematic manner by targeted qualification activities (for example by testing and
analysis)
— design monitoring activities that shall trigger specified risk reduction measures in the future.
The steps in the well qualification process are shown in Figure 7-1.
Current status of
existing wells from risk
assessment
Set requirements in
qualification basis
Modify qualification basis
Perform risk assessment
for well qualification
Plan well qualification &
select qualification activities
Evaluate likelihood
of success
Initial Well
Qualification
Report
M3
Evaluate need
for modifications
Yes
No
Execute well qualification
activities
Assess results against
requirements
Requirements met?
No
Yes
Final Well
Qualification
Report
M4
Figure 7-1
Flow diagram illustrating the well qualification process with respect to the milestones shown in Figure 2-1
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The result of well qualification is a Well Qualification Report that shall document the fitness for purpose of a
given well and define margins against specified failure modes or performance targets. The qualification results
may be used:
—
—
—
—
as an acceptance for use of an existing well for a CO2 storage application
for comparison between solutions for a given well
as input in the evaluation of the reliability of a CO2 geological storage site that the well may be part of
as an assurance of well integrity.
The following principles shall apply to well qualification:
— a qualification strategy shall be developed to bring a well from its current state to a defined target state or
to assess the present condition of the well
— specifications and requirements shall be clearly defined, quantified and documented
— the performance margins and the margins to failure shall be established based on recognised methods
— failure modes that are not identified may pose a risk to the successful use of the well; this residual risk shall
be managed by ensuring the relevant competencies are used (see Table 7-1) and by challenging the critical
assumptions during the course of qualification
— the qualification process shall be based on a systematic, risk based approach and performed by a
qualification team possessing all required competencies
— when service experience is used as proof of fulfilment of the specifications, then evidence of that
experience shall be collated and checked
— the work shall be documented and traceable
— an iterative approach is recommended when uncertainties are very large
— the typical quality assurance system for drilling, completing, and abandonment of a well shall be an integral
part of the qualification process.
Table 7-1 Competencies that a well qualification team shall possess.
Discipline
Expertise/knowledge required
Well engineering
Procedures for drilling, construction and permanent abandonment of wells
Materials/corrosion Characteristics of materials in well construction and their susceptibility to corrosion
Cements
Chemical and physical properties of different cement types
Interpretation of cement evaluation logs
Geochemistry
Geochemical interactions between injected or resident fluids, well materials, cements, rocks and
fluids in the near wellbore environment
Geomechanics
Potential geomechanical impacts on well cements and the near wellbore environment that may
stem from CO2 storage operations
Well integrity
Well integrity management and CO2 specific well integrity issues
Storage site
Storage site characteristics
characterization
Potential effects on the near-well environment if the site is or will be used for CO2 geological
storage (i.e., predicted changes in pressure, temperature and exposure to CO2 or fluids charged
with CO2 or other constituents in the CO2 stream)
HSE
HSE management and requirements in applicable regulations
7.2 Set requirements in qualification basis
7.2.1 General
The operator shall specify the qualification requirements for a given well in the Well Qualification Basis
document that shall include:
— a description of the current status of the well based on the findings of the Screening and Appraisal risk
assessments (Sec.4.3.6)
— the well performance requirements (Sec.7.2.2)
— the well specification (Sec.7.2.3)
— the critical parameters list for the well (Sec.7.4.2).
7.2.2 Well performance requirements
The well performance requirements shall:
—
—
—
—
define how the well will be used
define the environment that it is intended for
specify requirements such as acceptance criteria, performance expectations and qualification targets
include requirements throughout the extended life cycle of the well.
The well performance requirements shall reflect the storage site requirements specified in the Appraisal Basis
(Sec.4.3.2). Examples of well performance requirements are:
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reliability requirements related to selected functions
sustained annulus pressure limits
completion string leak rate limits
wear/corrosion tolerances within the completion string
casing corrosion rate limits.
7.2.3 Well specification
The well specification shall be described as completely and unambiguously as possible through text, drawings,
reports and other relevant documents. It is important that the well integrity criteria are stated and that all
relevant interfaces are clearly defined. The specification shall identify all phases of the well’s life and all
relevant main parameters.
Well specification may include, for example:
—
—
—
—
—
—
—
well description, schematic and formation boundaries and lithology types along the well
functional requirements
permit requirements
health, safety and environmental requirements
well integrity criteria
operation and maintenance, monitoring and abandonment principles
completion and interfacing with surface facilities.
The specification and functional requirements shall be quantitative and complete. In case quantitative measures
are not available for some of the requirements (for example, no cement evaluation log available) the
qualification can be carried out for a best estimate, but as soon as the target requirements can be quantified they
shall be entered into the well qualification basis and the implication of these new values shall evaluated.
7.3 Risk assessment for well qualification
7.3.1 General
The operator shall carry out an assessment of well integrity risks with respect to:
—
—
—
—
the current status of the well (from Screening and Appraisal stage Risk Assessments, see Sec.4.3.6)
the future function of the well (as specified in the Qualification Basis, see Sec.7.2)
the critical parameters list (see Sec.7.4.2)
the well component classification (see Sec.7.3.2.3).
The output from this risk assessment shall be a failure mode register containing identified failure modes and
failure mechanisms ranked according to their risk level. This register should be integrated with the overall risk
register or database for the storage site in question.
7.3.2 Risk identification
7.3.2.1 General
See Sec.6.3.2 for a general risk identification method description.
See Appendix A for examples of the types of well integrity data that should be collected and the information
that may be derived from each.
The operator shall conceptually subdivide the well into distinct and manageable components for risk
identification. See Appendix B for examples of components and their failure modes and mechanisms.
When performing this step the operator shall take into account:
—
—
—
—
—
well operations
well suspension
well abandonment
external failure modes for a well (not included in Appendix B), such as geological faulting
the underlying failure mechanisms that could lead to failure modes.
Well integrity risks for existing wells include both:
— existing inherent risks without CO2 storage
— additional risks caused by CO2 storage.
The latter is a function of the likelihood of:
— a well being exposed to the effects of CO2 storage (reservoir dynamics)
— well integrity failure in the event of such exposure.
The likelihood of the former will be a function of the CO2 storage volume that is defined for a given storage
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site and used to estimate capacity in the screen stage and is not discussed further in this step. The likelihood of
the latter is discussed further with respect to the direct effects on the near-well environment if the storage site
shall be used for CO2 geological storage. This includes:
— predicted effects of changes in pressure
— predicted effects of temperature changes
— predicted effects of exposure to CO2 or fluids charged with CO2 or other constituents in the CO2 stream.
Where the term CO2 is used in the guideline, it assumes that carbon dioxide is pressurized; may or may not
contain water; exists either as a liquid, super critical fluid or a gas; and also includes carbon dioxide dissolved
in water contained in the reservoir.
Predicted effects of changes in pressure may extend beyond the area of legal control of a project developer in
which case a mitigation plan may have to be put in place.
A number of co-components may typically be associated with industrial CO2 streams, such as those listed
below. The well qualification issues related to these are not specifically addressed in this RP, but may be
handled by the same qualification methodology:
— cracking and fouling associated with H2S either present in the injection stream or released in the geological
formation by CO2
— nitrogen and argon; these are non-condensable and will alter the vaporization and condensation properties
of the CO2 stream
— oxygen; this may increase corrosion rates
— hydrogen; this may limit materials of construction
— trace components, such as seal oil from compressors.
7.3.2.2 Special considerations for well integrity under exposure to CO2
Corrosion of carbon steel pipe and degradation of cement: the dominating failure mechanism related to longterm exposure to CO2 or CO2 saturated formation fluids is anticipated to be corrosion of carbon steel pipe and
degradation of cement. The probability of failure modes resulting from these failure mechanisms will depend
on the corrosion and degradation rates that are assumed. It is understood that international research and
development work continues in order to reach an industry consensus on how to predict these rates in a reliable
manner.
Elastomers: routinely used as sealing elements and can be found in surface and downhole valves, packers and
downhole seals. CO2 presents additional challenges to elastomer design. Elastomers shall resist explosive
decompression (rapid gas-decompression) and be qualified appropriately (refer to, for example NORSOK M710). Elastomer performance and properties change with time and they shall be avoided as part of the primary
abandonment barrier design.
CO2 as a refrigerant: designers shall be aware of the refrigerant properties of carbon dioxide. Large pressure
drop over a short distance will cause flowing CO2 temperatures to drop significantly. Materials of construction
shall ensure that toughness of metals and flexibility of elastomers (durometer) are maintained for both normal
and abnormal flow conditions. Low temperatures can also freeze annulus fluids and cause additional tubing
contraction, for example unstable flow regime down the tubing in low pressure reservoirs.
The temperature range could therefore be greater than normally experienced in a conventional oil and gas
injection well and may cause considerable expansion/contraction and additional loads on the well.
Blow-down considerations: blow-down of CO2 in liquid or super critical phase is a challenge. In addition to
the low temperatures, dry ice can form which may land locally and create hazards, or in extreme cases cause
erosion of the vent pipework. Design of wireline and coiled tubing systems and operations shall take this into
consideration, for example by displacing the CO2 with nitrogen before de-pressurisation. This operational need
also exists with downhole safety valve testing and this may be the dimensioning case for surface pressure
control equipment.
Annulus management: the qualification process shall examine the management of the annulus condition during
the injection phase to detect well integrity problems early and prevent corrosion of casing and tubing. Condition
monitoring of the annulus during the injection phase could include pressure monitoring, measurement of topup volumes, sampling of annulus fluids, and pressure-volume measurements.
7.3.2.3 Well component classification
The operator may choose to classify well components according to common failure mechanisms in order to
facilitate the process of risk identification.
Well component classification is a qualitative process that shall make use of a failure mechanism (such as
corrosion) that is common to the components in question. In the case of corrosion then the well components
shall be classified according to the corrosion resistance of their materials and their degree of expected exposure
to a corrosive environment. In examining the well components it may be beneficial to group them into subsystems (such as the lower completion) prior to performing the classification.
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An example of such a rating system is shown in Table 7-2. The term ‘technical uncertainty’ relates to the
potential incompatibility or poor performance of components, whereas the term ’technical challenges’ relates
to components of known incompatibility with CO2 and where performance can be modelled.
A well component or sub-system rated as Class 1 in this example shall be proven to be of no particular concern
for the application in question through documentation of tests, calculations and analysis. Such components do
not require qualification and shall be handled through the regular design process.
A well component or sub-system rated as between Class 2 to Class 3 in this example has an increased degree
of technical uncertainty. Components falling into these classes shall be qualified according to the work process
described in this document.
Components falling into Class 4 likely require modification (see Sec.7.6).
Table 7-2 Example classification system for the
corrosion resistance of well components
Exposure to CO2
corrosion
Corrosion resistance
High
Medium
Low
Low
1
2
3
Medium
2
3
4
High
3
4
4
Where:
Class 1 represents no technical uncertainties;
Class 2 represents new technical uncertainties;
Class 3 represents new technical challenges;
Class 4 represents demanding technical challenges.
7.3.3 Risk analysis
See Sec.6.3.3 for a general risk analysis method description.
The operator shall make use of quantitative measures of likelihood and consequence where this is supported
by the available data.
7.3.4 Risk evaluation
See Sec.6.3.4 for a general risk evaluation method description.
The operator shall distinguish between the following three qualitative risk classes as a minimum:
— low risk – failure modes that do not require qualification and may be adequately resolved by qualified
personnel
— medium risk – non-critical failure modes that require qualification to reduce their risk
— high risk – critical failure modes that require qualification to reduce their risk.
The operator shall establish a failure mode register for tracking the status of each failure mode and mechanism
throughout the qualification process. The risk evaluation shall be updated as new information arises and failure
modes with low risk should not be deleted from the list. This system shall include:
— all identified failure modes and mechanisms
— a probability estimate for each failure mode to occur
— the basis for the probability estimate tracing documentation revisions and implementation of mitigating
actions
— the degree of CO2 implications to which the failure mode relates (Class 2 to 4 from Table 7-2) in order to
focus on the important components.
7.4 Plan well qualification & select qualification activities
7.4.1 General
The operator shall develop a plan that describes the qualification methods that shall be applied to reduce the
risk(s) to well integrity.
Development of the well qualification plan shall include:
— high level planning to implement the overall qualification process
— analysis and selection of qualification activities to provide the evidence needed for each failure mode
— development of the reasoning that connects the evidence produced by the qualification activities to the
requirements set in the qualification basis
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— development of detailed specifications of the qualification activities.
The detailed specifications of qualification activities shall explicitly specify:
—
—
—
—
—
the evidence to be produced by each qualification activity
the failure modes that evidence relates to
the reasoning that relates the pieces of evidence to the failure modes
the reasoning that relates the evidence to the requirements specified in the qualification basis
success criteria for this evidence to demonstrate fulfilment of the qualification requirements.
The well qualification plan shall be revised as necessary.
7.4.2 Critical parameters list
The purpose of the critical parameters list is to document the vital governing parameters affecting the failure
mechanisms, for example the parameters affecting the rate of casing corrosion, such as material composition,
temperature, chemical composition of fluids, etc.
Hence, at the conclusion of the well qualification process, the boundary limits for the parameters and items
given in the critical parameters list will represent the qualified limits or operating envelope within which the
well is considered qualified.
The operator shall determine governing parameters for critical failure mechanisms. The critical parameters list
shall specify such governing parameters, and include their limits/boundaries within the scope of the
qualification. Further, this list shall also specify the main concerns and uncertainties with the given parameters.
7.4.3 Selection of qualification activities
Qualification activities shall be selected in order to meet the requirements given in the qualification basis.
If a quantitative reliability target is stated in the qualification basis, then a quantitative reliability method is
required to document fulfillment of the requirement, for example by determination of a lifetime probability
density distribution for the relevant failure modes.
For each failure mode of concern, it shall be determined if the failure mechanisms can be modelled by
recognised and generally accepted methods. Then a detailed plan for the qualification activities can be
established, for example, by use of existing standards or industry practices.
The following methods can be used, separately or in combination, to provide qualification evidence:
— failure mode avoidance, such as operational procedures or design changes
— analysis or engineering judgement of previous documented experience with similar equipment and
operating conditions
— analytical methods such as handbook solutions, methods from existing standards, empirical correlations or
mathematical formulas
— numerical methods, such as process simulation models, computational fluid dynamics, finite element
modelling, coupled geomechanical and reservoir simulation modelling, corrosion models, etc
— experimental methods, scale model testing, identification or verification of critical parameters and their
sensitivities.
Qualification activities may consist of qualitative and quantitative methods, analysis and testing. A typical
qualification program may include a combination of the following activities:
— material corrosion resistance, historical data, corrosion prediction models, testing
— documenting field history, quantitative/ qualitative evaluation of failure history of wells in a field with
similar wells and exposure
— assess documented industry practice with the specific well components
— predictive modelling of CO2 movement and possible contact with components that might degrade if exposed
to either CO2 or CO2-saturated brines, and modelling to estimate degradation processes, rates and end points.
7.5 Evaluate likelihood of success
The operator should evaluate the likelihood of success for achieving qualification of a well in a qualitative
manner based on the technical challenges and the available time for qualification.
The operator may also perform a more sophisticated assessment of the total likelihood of success for all wells
as function of time. Such an assessment requires that both the probability of a successful outcome for each
activity and the uncertainty in the durations are estimated.
An economic assessment of the qualification activities may be carried out following the same principles, where
the time parameter is replaced by costs. This requires that cost estimates with uncertainties are estimated for
each qualification activity.
In the event that further development of a storage site is anticipated then a project developer shall consider
initiating baseline monitoring of existing wells at the earliest possible opportunity.
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7.6 Evaluate need for modifications
Modifications of the well and/or the qualification basis may be considered if the likelihood of successful
qualification is low and/or the associated time and cost are high.
If the estimated likelihood of success is unacceptable and required modifications are excessively costly, the
well shall not be considered for further qualification and the storage site containing such a well shall be
eliminated from the list of potential storage sites at Milestone M3.
7.7 Update qualification basis
The objective of this step is to update the qualification basis in light of new information that may come to light
during the qualification process. Modification to the well qualification basis shall have a defined purpose, such
as:
— change of intended well function (possibly in order to avoid a particular failure mode)
— reduction of the probability of occurrence or consequence of failure mode to an acceptable level
— reduction of the total well cost.
Any modifications to the well qualification basis imply that the well qualification steps need to be updated. The
update may range from a limited update of parameters or risk data to major re-design of the well. In either case
documentation is required in order to maintain traceability of the process.
7.8 Initial Well Qualification Report
The operator shall document the well qualification findings for each well thus far in the process in an Initial
Well Qualification Report. The purpose of this report is to support the selection of a storage site and the
operator shall include this report in the Well Engineering Concept (Sec.4.3.8).
An Initial Well Qualification Report for each well shall describe:
— the required qualification activities
— the likelihood of successful qualification
— time and cost estimates for completion of well qualification.
7.9 Execute well qualification activities
7.9.1 General
The operator shall execute the well qualification activities specified in the Initial Well Qualification Report
according to industry recognised standards and document any assumptions made.
7.9.2 Failure mode detection
Failure modes detected during execution of the qualification activities (quality control qualification test,
acceptance tests or later operations) shall be recorded and documented. The documentation shall include the
date detected, the description of the failure mode, other observation and the identity of the originator.
When a failure mode is detected in the qualification process, the occurrence of the failure mode shall be
evaluated with regard to the three following cases:
— will occur within the expected frequency of occurrence according to the analysis
— will occur with a higher frequency
— has not been considered.
In the second case the basic assumption for the frequency of occurrence shall be re-evaluated. This reevaluation shall include implications for any models used.
In the third case there shall be an evaluation stating if the failure mode is an artefact that need not be considered
or if it was missed and must be included in the qualification.
7.9.3 Collection and documentation of data
The documented evidence from the execution of the qualification activities shall enable the performance
assessment step to be carried out. The failure mode register from Sec.7.3.4 shall be used to follow up the data
collection and the qualification of the well.
7.9.4 Ensuring traceability of data
The operator shall establish an “audit trail” in order to ensure the traceability of data throughout the
qualification process. Data shall be organized in such a manner that there is a clear link between the steps of
the qualification process, from the qualification basis to performance assessment. It shall be possible to trace
the threads that have been identified, how they have been addressed (test, analysis, previous experience, etc.),
what evidence has been developed (test and analysis reports), and how that evidence meets requirements in the
well qualification basis.
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This step provides an opportunity for independent review of the qualification conclusions and will enable reuse
of evidence in future projects, for example qualification of other wells or the same wells for a different use.
A fit for purpose electronic database should be used to enhance the traceability of data as described above.
7.10 Performance Assessment
The operator shall assess if the well qualification has been successful by comparing the available evidence
against the requirements specified in the well qualification basis.
If the performance assessment concludes that some requirements are not met, risk control options
(modifications to the well) and further qualification activities shall be identified. This may include tightening
of the operating envelope for the well or enhanced inspection, workover and intervention strategies to meet the
requirements based on the existing evidence. If none of these options are feasible, the well cannot be qualified
against the well qualification basis.
Performance assessments may also be performed at defined points in time during operation to confirm that the
operations are within the assumptions for qualification stated in the Qualification Basis.
Key steps in the performance assessment are to:
— interpret the evidence to account for simplifications and assumptions made when the evidence was
generated and limitations and approximations in the methods used
— confirm that the qualification activities have been carried out and that the risk criteria have been met. A key
part of this confirmation is to carry out a gap analysis to ensure that the qualification evidence for each
identified failure mode meets the specified risk criteria
— perform a sensitivity analysis of relevant parameter effects
— assess the confidence that has been built based upon the qualification evidence through the qualification
activities. This shall consider the extent to which test specifications have independently reviewed and test
witnessed by an independent party
— compare the failure probability or performance margin for each identified failure mode of concern with the
requirements in the qualification basis. Evidence shall be propagated from individual technology
components to the requirements specified for the entire system covered by the qualification.
The assessment findings may be represented as safe service envelopes such that a wider range of operating
conditions is covered than those specified in the well qualification basis. This can greatly simplify qualification
for modified operating conditions.
7.11 Requirements met?
Depending on the findings of the previous step the operator shall decide on the need to modify the qualification
basis.
7.12 Final Well Qualification Report
The operator shall document the well qualification findings for each well in a Final Well Qualification Report.
This report shall be included in the Injection and Operating Plan (Sec.5.4.3) within the Storage Permit
application (Sec.5.4).
A Final Well Qualification Report for each well shall document whether or not:
— the qualification activities stated in the Initial Well Qualification Report have been completed
— the acceptance criteria for the qualification activities have been met
— the functional requirements and target reliability as stated in the qualification basis have been met.
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App.A Subsurface Data – Page 49
APPENDIX A SUBSURFACE DATA
Seismic
Table A-1 Examples of relevant subsurface data and the information that may be derived from each.
Data type
Information derived
Records of earthquake magnitudes,
- background levels of natural seismicity.
locations and depths
Regional
seismology Maximum ground motion velocities and
- magnitude and orientation of regional stress field.
displacements
- regional structural cross sections
Regional 2D
seismic lines Time and depth migrated seismic sections - lateral distance to subcrop/outcrop of formations
- regional map of lateral continuity of the primary seal.
- detailed structural imaging
- location, orientation and throw of geological faults
- 3D time and depth formation horizon maps
Field specific Time and depth migrated 2D sections and
- large-scale vertical and horizontal reservoir
2D and 3D
3D volumes
stratigraphic features, particularly unconformities,
seismic
erosional surfaces and heterogeneity
- detailed, local map of lateral continuity of the
primary seal.
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Table A-1 Examples of relevant subsurface data and the information that may be derived from each. (Continued)
Data type
Information derived
- formation resistivity
- indication of porosity
Resistivity/Conductivity logging
- indication of pore-fluid
- indication of permeability, if resistivity/ conductivity
data with varying depth of investigation are available.
- rock characterization
Gamma ray logging
- formation boundaries.
- boundaries of permeable formations
Spontaneous Potential logging
- well correlation
- stratigraphy
- lithology
- depositional environment
Petrophysical Neutron/Density
well log data
- porosity
- permeability
- indication of pore fluid.
Temperature logging
- temperature.
Well related
Caliper/dip logging
- orientation of stress field.
- porosity
- lithology
Sonic logging
- rock matrix mechanical properties and related
parameters for seismic survey processing.
- orientation of ‘breakouts’ from wellbore, orientation
Micro-resistivity, Downhole video imaging and spacing of fractures or other weak planes,
indications of magnitude and orientation of principal
stresses.
- fracture initiation pressure in the zone for which the
leak-off is being applied, pressure communication
Leak-off tests, short or extended
between zones.
- effective reservoir permeability in zone near
Production and or injection followed by a
wellbore, formation damage near wellbore, qualitative
shut-in pressure buildup (for production
indication of flow “boundaries”. For small connected
Well test data test) or shut-in pressure “falloff” (for
reservoir volumes, can also indicate overall connected
injection test)
reservoir volume if test lasts long enough.
- effective reservoir permeability in zone between
Interference tests, i.e. pressure measurement wellbores, qualitative indication of flow “boundaries”.
in neighboring wells at least one of which is For small connected reservoir volumes, can also
indicate overall connected reservoir volume if test
either producing or injecting
lasts long enough.
- composition and variability of the formation fluids,
particularly the presence of natural CO2, natural inert
components or other important components that might
react with the injected CO2 in:
Downhole fluid sampling data
- the injection zone
- other permeable units in the storage complex
- the first permeable unit overlying the storage
complex, if present.
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Well related
Table A-1 Examples of relevant subsurface data and the information that may be derived from each. (Continued)
Data type
Information derived
- capillary pressure as a function of saturation, for the
relevant CO2 and formation fluid system in the
injection zone, including residual (irreducible) water
and CO2 saturations
- porosity
- relative permeability
- capillary entry pressure of the primary seal
- type of pore fluid
- characterization of clay minerals, tendency of
Core plug test data
isolated clay particles to be released and potentially
cause plugging
- mineralogy of the rocks in the storage complex,
including composition of the carbonates, clays and
feldspars if present
- deformation properties of formations including
Poisson’s ratio and Young’s modulus with appropriate
spatial variations
- thermal properties including thermal expansion
coefficient, specific heat capacity, thermal
conductivity.
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Well related
Table A-1 Examples of relevant subsurface data and the information that may be derived from each. (Continued)
Data type
Information derived
Well coordinates
- number and location of wells.
Well schematics
- as built construction.
- well construction
- quality of execution
Drilling reports including drilling fluid
reports
- problem areas
- wear points.
- geological formation and hole condition prior to
Open hole log data including calliper logs setting casing.
Cement evaluation logs
- cement position and quality.
Cement placement data including centralizer - cement position and quality.
programme
Cement design and related laboratory
- mechanical and chemical properties of cement.
reports
- tubular connection and jewellery depths
Well completion logs
- condition of the above.
- age of equipment
Dates of spudding, workovers and
abandonment
- history of the well.
Description of materials and cements used - mechanical and chemical properties.
- geological formation strength
Well integrity Results of mechanical integrity tests
data
performed on the well
- cement quality.
- integrity of casing and well barriers
Annulus pressure/fluid sampling
- seal leak rates.
Visual inspection of the sealed top of the
abandoned wellbore with possible bubble
- integrity of the abandonment.
tests
Records of leak tests performed before
- integrity of the abandonment.
abandonment
Other information such as the presence or
- integrity of casing and well barriers.
absence of sustained casing pressure
List of operators (drilling operator, well
- sources of further information.
operator, logging operator, etc.)
Track record of relevant regulatory changes
regarding drilling and abandonment
- gaps with respect to current regulations.
practices
Geomechanical history of the field including - stress/strain/shear history of the well.
subsidence
Industrial history of the area including
- history of external factors on the well.
drilling, injection, production and mining
- reservoir history
Records of temperature and pressure and
composition of formation fluids over time - wellbore chemical exposure history.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
App.A Subsurface Data – Page 53
Non-technical data
Table A-1 Examples of relevant subsurface data and the information that may be derived from each. (Continued)
Data type
Information derived
Hydrocarbon reservoirs, mineral resources,
coal seams and geothermal energy
extraction potential in zones above and
below intended storage formation that may
be impacted by CO2 geological storage
project, and the status and ownership of
these zones.
Ownership and status of intended storage
formation.
- hydrocarbon exploration and production
developments.
Surface infrastructure and facilities
(buildings, transportation corridors (roads,
railroads, pipelines and pipeline right-ofways, etc.), power distribution lines, oil and
gas production and processing facilities,
groundwater reservoirs, etc.)
Subsurface infrastructure and facilities
(wells, mines, waste repositories, gas
Conflict of storage sites, acid gas disposal sites, etc.)
interest
Map of zones containing protected
groundwater or zones with groundwater
which are used in other subsurface
development, and for which pressure
- groundwater usage.
depletion/build-up may impact or be
impacted by the planned CO2 geological
storage project.
Existing pipelines and pipeline right-of- pipelines.
ways.
Stakeholder map and plan to carry out a
- mapping of stakeholders and assessment of public
stakeholder assessment
perceptions of CO2 geological storage.
Map of protected or reserved areas
Map of access pathways (pipeline right-ofways and location of roads and other
infrastructure needed for operation of CO2
geological storage project.
Applicable legislation, regulations and
and initiatives to introduce new or
Regulatory directives
modify existing legislation regulations and
directives.
Climate, atmosphere and meteorology,
Environmental ecology, wildlife, plants, parks and reserves
Demography and historical factors that can
influence how the project will affect and be
viewed by the local population.
Societal
Political, cultural and regional economic
circumstances that may influence the
success of the project
- assessment of legal and physical accessibility to
injection zones.
- regulatory restrictions, e.g., environmental
regulations, trans-border transportation/migration
issues.
- surface and marine environment.
- demography and political, cultural and economic
environment.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
App.B Generic failure modes for well integrity under exposure to Carbon Dioxide – Page 54
APPENDIX B GENERIC FAILURE MODES FOR WELL INTEGRITY
UNDER EXPOSURE TO CARBON DIOXIDE
Table B-1 Generic check-list of failure modes and failure mechanisms for wells under exposure to carbon
dioxide (CO2).
No. Well Component Failure mode
Failure mechanism
1
Well
1.01 Any part of the
Misjudgment of
- missing critical data
well
status
- poor data.
2
Upper Completion
2.01 Production packer Material yields or - materials of construction lose their mechanical strength and begin to
(including seal
cracks
yield (hot), or brittle fracture if subjected to very cold conditions
assemblies)
- materials on construction do not have capacity to resist pressure forces.
2.02
Material
- compatibility with CO2 and other trace products in fluid stream
degradation
- degradation under chemical stimulus
- H2S cracking (corrosion) (Consider if H2 is likely).
2.03
Unreliable material - explosive decompression
performance
- improper hardness at all conditions
- degradation under chemical stimulus or under production fluid
conditions.
2.04
Slipping
- thermal expansion (or contraction) of tubing places additional load on
locking mechanism
- locks attempt to hold on to a worn or corroded casing wall
- unstable well flow cycles material to fatigue failure.
2.05 Tubing and
Material
- corrosion from fluids or from annulus souring
jewelry
degradation
- erosion (high flow rates, wireline intervention, tubing movement).
2.06
Material yields
- pressure and temperature causes metal to yield
(cracks)
- unstable flow causes fatigue
- improper tubing movement causes buckling or necking.
2.07
Tools stuck
- tubing and liner not in gauge.
downhole
2.08 Completion
Material
- corrosion from fluids or from annulus souring
String Couplings degradation
- erosion (high flow rates, wireline intervention, tubing movement).
2.09
Material yields
- pressure and temperature causes metal to yield
(cracks)
- unstable flow causes fatigue
- improper tubing movement causes buckling or necking.
2.10
Seal fails
- improper coupling connection used for CO2 service (no metal to metal)
- improper assembly of coupling
- coupling damaged before or during make-up
- coupling backs off
- corrosion cell within coupling threads
- couplings back-off during running (rotation).
2.11 Surface controlled Material
- corrosion from fluids
subsurface safety degradation
- erosion (wireline intervention, high flow rates)
valve (SCSSV)
- elastomer explosive decompression
- elastomer degradation under fluids
- elastomer hardness poor under certain conditions.
2.12
Material yields
- materials on construction do not have capacity to resist pressure forces
(cracks)
or remain ductile at certain temperatures.
2.13
Control line failure - control line blockage
- control line disconnects from coupling
- control line breaks owing to fatigue
- control line is eroded by rubbing.
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
App.B Generic failure modes for well integrity under exposure to Carbon Dioxide – Page 55
Table B-1 Generic check-list of failure modes and failure mechanisms for wells under exposure to carbon
dioxide (CO2). (Continued)
No. Well Component Failure mode
Failure mechanism
2.14 Wellhead &
Material
- explosive decompression
Christmas Tree
degradation, or
- improper hardness at all conditions
unreliable material - degradation under chemical stimulus
performance
- degradation under production fluid conditions.
2.15
Material yields
- materials of construction lose their mechanical strength and begin to
(cracks)
yield (hot), or - Brittle fracture if subjected to very cold conditions
- materials on construction do not have capacity to resist pressure forces.
2.16
Corrosion of metal - thinning of pressure envelope owing to corrosion
from inside
- embrittlement if H2S is present and not to NACE standard.
2.17
Cracks from
- hydrogen embrittlement
cathodic
- external corrosion.
protection;
Corrosion from the
environment; loss
of containment
2.18
Stress from piping - piping and tree movements place unacceptable stress on wellhead
on tree
- “water Hammer”.
2.19
Stress from well
- structural events and tree movements place unacceptable stress on
supporting
wellhead.
structure and
environment
3
Lower Completion
3.01 Open hole CO2 is not injected - thief zone.
uncased
in the zone of
interest
3.02 Sand control
Equipment failures - materials incompatibility
- deterioration of equipment
- mechanical failures of equipment.
3.03 Stimulation
Fracture of cap
- hydraulic fracture job.
rock
4
Casing/Liner/Cement
4.01 Casing/Liner
Material Degrades - corrosion from annulus fluids (aerobic or anaerobic)
- corrosion from reservoir fluids; (only for the production string)
- embrittlement from sour annulus.
4.02
Material yields
- materials on construction do not have capacity to resist pressure forces
(cracks)
or remain ductile at certain temperatures; (this only applies to the strings
that actually see the CO2).
4.03
Tools stuck
- tubing and liner not in gauge.
downhole
4.04 Connections
Material
- corrosion from annulus fluids (aerobic or anaerobic)
degradation
- corrosion from reservoir fluids
- embrittlement from sour (H2S) annulus.
4.05
Material yields
- materials of construction do not have capacity to resist pressure forces
(cracks)
or remain ductile at certain temperatures
- local stress associated with rock movements place excessive stress load
on casing causing collapse
- drilling dog-leg adds additional stress
4.06
Seal fails
- coupling incorrectly installed
- rock movement stresses pull couplings apart (axial) or collapse
(pressure)
- coupling backs off during running (rotation).
4.07 Conductor
Corrosion of
- collapse under weight.
surface conductor
onshore and
platform wells
4.08
Hydraulic damage - collapse under weight.
of foundation soils
around surface
conductor
DET NORSKE VERITAS AS
Amended July 2013 see note on front cover
Recommended Practice DNV-RP-J203, April 2012
App.B Generic failure modes for well integrity under exposure to Carbon Dioxide – Page 56
Table B-1 Generic check-list of failure modes and failure mechanisms for wells under exposure to carbon
dioxide (CO2). (Continued)
No. Well Component Failure mode
Failure mechanism
4.09 Cement
Leak behind casing - CO2 degradation of cement
- H2S degradation of cement
- magnesium chloride degradation
- thermal cracking and/or de-bonding (micro-annulus between cement
and casing) due to Joule-Thomson effect during injection into, e.g.,
depleted gas reservoir
- pre-existing channels in cement
- pre-existing micro-annulus between casing and cement.
4.10
Cracked cement
- different relative movement along wellbore due to subsidence of
and casing and/or reservoir and/or expansion due to injection (e.g. “shear, kink, collapse”).
de-bonding
4.11
Poor cement job
- centralisers did not function properly, mud wiper trip before cementing
did not remove mud residue effectively.
4.12
Damaged cement - pressure tests (higher pressures)
across reservoir
- temperature and pressure cycling
interval
- acids, chelators, stimulation.
5
Annuli
5.01
Frozen well
- leak to annulus
- cold fluid entering tubing.
6
Injection system
6.01
Unintended phase - both gas and dense phase CO2 present in the wellbore.
change in the
wellbore
6.02
Equipment failures - pipeline specs inconsistent with material specs of well.
6.03
Tubing shocks
- fluctuations due to start up (phase transition).
DET NORSKE VERITAS AS