I OIL AND GAS I TECHNOLOGY I
The 3D model is becoming the default platform for analysis and decision making
A powerful reservoir management
solution for our times
By : Elizabeth Thompson, Emerson Process Management, Roxar
This article will take you through the different stages of the 3D
modelling process and will also look at the crucial role IT and a strong
workflow play throughout.
What do you know about
your reservoirs? The rise
of 3D modelling
From seismic surveys to production
history, today’s hydrocarbon industry generates huge amounts of data
from its oil & gas reservoirs. IBM
Business Consulting Services recently estimated that a single oil or
gas field can generate on average
up to one terabyte of data per day1.
The organisation of this data
and its transformation into valuable
decision-making information is one
of the industry’s greatest challenges. Get your interpretation of
the data wrong and bid valuations,
new field development plans, and
production estimates will all suffer.
The North Sea is a case in
point. Here, reserves have increased or decreased by more than
50% in more than 40% of the
fields2, leading to the requirement
to drill 60 to 80% more wells than
originally anticipated.
One means of making better
use of your data is through the creation of 3D models. 3D models are
a focus for scenario generation, a
tool to explore possibilities, and a
place to store and analyse information.
The 3D model is becoming the
default platform for examining and
understanding subsurface geology.
It improves communication be-
tween colleagues. It allows different ideas to be evaluated. It provides the reservoir engineer with
better quantification of the uncertainty within the reservoir. Areas of
the reservoir which require more
detailed analysis can be determined. More accurate assessments
and predictions of reservoir performance can be generated. The result
will be reduced levels of financial
risk.
In order to provide the most
reliable plans for the future, however, it is essential that your 3D
model is as accurate as possible, as
continuously as possible. This accuracy is vital, since the geometry and
properties of the model determine
1
IBM Business Consulting Services – Meeting the Challenges of Today’s Oil & Gas Exploration and Production Industry.
2
The Norwegian Petroleum Directorate, May 2003.
3
Tackling the Oil and Gas Industry Skills Gap, Booz Allen Hamilton, January 2008
DEW JOURNAL November 2009
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The Roxar industry leading reservoir modelling solution - RMST contains state of the art tools to
conduct 3D uncertainty assessments
where and how big the hydrocarbon
accumulation may be.
This article will take you
through the different stages of the
3D modelling process and will also
look at the crucial role IT and a
strong workflow play throughout.
Developing the
production plan
Once you have found a good prospect and proved it with a couple of
wells, the next stage is to develop a
detailed production plan.
You need to know how much
actual reservoir there is, where it is,
how good the porosity is and where
the best well locations are for maximum recovery. You also need to
have an accurate idea as to what
will happen in the reservoir when
you initiate production.
3D models can provide this information. Emerson Process
Management’s Roxar provides an
industry leading reservoir modelling
solution, RMS™, containing state of
the art tools to conduct, for example,
3D uncertainty assessments.
What if the depth conversion is
a little inaccurate? What happens if
Simulation with the parallelised Tempest can handle multi-million cell models with thousands of wells
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DEW JOURNAL November 2009
the water saturation is a little different? What happens if the net to
gross is more variable than expected? These are all questions
which can only be reliably addressed using 3D models.
While there will always be a
certain degree of uncertainty in
operator decisions, today’s 3D reservoir modelling techniques can
better quantify these uncertainties,
whether they lie in depth conversion, structural modelling, geological property modelling, or dynamic
reservoir simulation.
Take RMS™’s property modelling tools - techniques which combine seismic and well data with
geological understanding to generate the most accurate and best constrained model for describing which
rocks are where. From ‘simple’
indicator modelling extrapolating
well information, to more complex
multi-point statistics which can produce sophisticated geological scenarios, 3D modelling can ensure
that the full impact of often independent uncertainties is captured.
Another common challenge is
finding that reservoir performance
is significantly affected by fractures.
Fractures play an important role, both
positive and negative,
in the fluid flow
behaviour of many
fields. They can
greatly enhance the
permeability of rocks
and will change the
distribution of flow in
the reservoir through
altered connectivity
patterns. Their influence can be particularly profound in carbonate fields and
basement reservoirs,
where they can critically affect reservoir
performance and be
potentially fatal to
individual wells.
In this context,
where approximately half of the
world’s proven reserves of oil and
gas are in carbonate or fractured
reservoirs, full-field fracture modelling is essential to gain a clear understanding of how the field is
likely to behave. As fractured fields
also display a greater potential for
variation in performance through
time, an up-to-date and accurate
model is crucial for planning and
managing long-term field performance.
Roxar provides an integrated,
easy to use fracture modelling package which enables geologists and
reservoir engineers to create detailed and reliable permeability
maps. Using these in flow simulation and history matching of reservoirs to quantify uncertainties allows the team to make sensible risk
avoidance plans.
The Roxar Fracperm software,
which is integrated with the main
Roxar modelling and simulation
suites, combines data, geological
properties, geo-statistics and geohistory in a data-driven approach. It is
designed to make maximum use of
available data and allow rapid and
interactive quality control of the
model as it is being
built. It can also link
with the Roxar history
matching solution,
EnABLE™, to provide a
single workflow
where uncertainties
can be monitored,
their impact assessed
and technical effort
focussed where it will
make most difference.
Furthermore,
Fracperm’s non-specialist, practical approach means that
the asset team, who
know the field best,
can build and refine
their own models.
Using advice and QC
from experts makes
maximum use of both
Extracting information directly from seismic data greatly increases the power and accuracy of facies
modelling techniques
expert and non-specialist staff and
brings fracture modelling into the
mainstream.
Once you have a good appreciation of the sub-surface geology, the
next question is where to drill.
RMS™’s well planning tools
allow the geologist to plot and refine well trajectories to maximise
extraction, minimise costs and
avoid collisions. Proposed wells can
even be included in streamline runs
to assess their likely performance.
Numerous potential locations can
therefore be proposed and examined in the virtual world before
committing time and money to actually drilling.
Hitting the target - realtime adjustments
One of the biggest challenges in
reservoir modelling today is the
delay between the analysis and
integration of real-time drilling data
and the updating of the geological
model. Delays can lead to crucial
information not being available to
the decision-making process as the
drilling takes place.
To meet these challenges,
Roxar has developed a real-time
geosteering methodology where
the continuous flow of available
data can be smoothly integrated
into the model. Measurement while
drilling (MWD) and logging while
drilling (LWD) data is used to evaluate the position of the well, assess
the physical properties of the rocks
and fluids drilled, and analyse the
behaviour of the drillstring in realtime.
The monitoring of the reservoir
consists of gathering different
FracPerm helps asset teams model their field behaviour without needing external experts to build the model
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types of real-time information, such
as survey data, LWD data, drilling
information and bottom hole assembly information for the different
drilling phases. All of this data can
be displayed in multiple views in
combination with elements of the
geological model.
Roxar’s geosteering functionality can then monitor the proximity
between the bit and objects in the
model. Alarms can be triggered
when approaching or exiting proximity to objects in the model, for
example, a fault, the reservoir top or
the oil-water contact. The position
of the well under monitoring is automatically quantified within the
geological model with this being
achieved through the continuous
real-time updating and adjustment
of well paths from current positions
(real and modelled) and targets.
Locating the position of the LWD
tool’s sensors within the geological
model; monitoring in real-time the
proximity between the well and objects in the model; and using a
workflow-based approach to update
the model while drilling: all these allow the operator to make timely, informed decisions, and reduce the risk
in well planning and drilling.
And the result for the operator?
Improved wellbore stability and
hole quality, and optimised well
paths, leading ultimately to fewer,
cheaper and more productive wells.
Managing Mature Fields
Managing a mature field brings a
number of challenges in its own
right. It means dealing with not only
the geology, but also the impact of
decisions made when the field was
young and less well-understood.
Here a 3D model is vital for
documenting the history of the field,
and building a picture of how the
way it has been produced will affect
the way it can be produced in the
future. The model can examine the
impact of proposed enhanced oil
recovery (EOR) processes, such as
gas or water flooding and pressure
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DEW JOURNAL November 2009
support, individual well stimulation,
or expected behaviour from the different patterns of infill drilling.
The rise of robust and fast reservoir simulation and computer
assisted history matching - the act
of adjusting a reservoir model until
it closely reproduces the observed
field behaviour - has played a crucial
role not only in mature fields but
across the reservoir lifecycle.
History matching, for example,
is critical for monitoring displacement processes, predicting future
performance and estimating where
our knowledge of the reservoir is
incomplete. It also plays a key role
in developing an integrated approach to reservoir management
because it allows the static geological model to be synchronised with
production data.
In this way, the rise of computer
assisted history matching has allowed the engineer to focus on developing an understanding of physical mechanisms active in the reservoir during production and their relative impact on production behaviour.
Powerful statistical techniques can
be used to determine multiple models of the reservoir that will provide
good matches to the production
history. An analysis of these models
will, in itself, provide information on
uncertain areas or properties.
The history matched results are
then used with the simulator to
predict how a field’s future performance may look and give measures
of the uncertainty about these predictions. In this way, it brings geological modelling and simulation
closer together and provides valuable information on the economics
of the reservoir.
Improving production
performance estimates
The Roxar history matching solution,
EnABLE™, is used by operators
worldwide to gain a better understanding and measurement of uncertainty in reservoir performance
estimates.
EnABLE™ allows the engineer
to choose parameters to which
model performance may be sensitive. Assisted history matching software can evaluate the impact of
individual parameters, thereby assessing which parameters need to
be changed and exploring how they
could be changed in order to
achieve a history match.
The ability to distinguish between critical modelling parameters, either static or dynamic, and
parameters which will have little
impact on decision-making is crucial, allowing resources to be deployed efficiently, and ensuring that
people can better target the physical assets.
Furthermore, real-time data
from the field, such as pressure,
temperature and flow rates, and
other available data, such as seismic,
petrophysical and facies updates,
are also used to update the model
and quantify structural and reservoir
property uncertainties in real-time.
The end result is a rapid model
updating workflow, running on a
continuous basis as new production
data is gathered. Roxar’s goal is to
develop a ‘big loop’ workflow of
reservoir management that carries
uncertainties and details in the geologic model through to simulation.
This is now being achieved.
And the recent introduction to
the market of the latest version of
EnABLE™ - EnABLE™ 2.3, will take
this process even further forward.
EnABLE™ 2.3 comes with simplified workflows, new and improved
diagnostics, statistical engine advances and better interfaces with
reservoir simulators. The result will
be the ability for operators to estimate technical and economic uncertainty within their reservoirs even
more accurately and comprehensively than previously.
Moving towards a digital
future
This article has taken the reader
through the reservoir modelling,
simulation and history matching
process. At all stages, IT has played
a vital role. Let’s take a look at
some areas.
Firstly, the rise in computing
power has played an integral role in
creating an enhanced reservoir
modelling workflow.
Distributed computing, improved visualisation, collaborative
tools and ever more sophisticated
Supervisory Control and Data Acquisition (SCADA) systems have all
brought the oilfield closer to the
geoscientist.
The rise in computing power
has also led to increased efficiencies within the asset team. With
expert, experienced personnel
scarce and teams frequently spread
across different countries, the increased connectivity of a generation of internet-native geoscientists
allows the sharing of experience as
never before. Collaborative work
through teleconferencing and
shared models is the only way to
ensure that both deadlines are met
and high standards are maintained.
In the long run, this sharing of expertise benefits the entire company. Take reservoir simulation, for
example.
The rise of desktop parallel
processing via the new 64-bit multi
core chips, and increasingly affordable clusters, means that multimillion cell reservoir simulation
models are now increasingly common. Algorithmic developments,
such as single grid dual porosity
modelling, and software developments, are all leading to higher
resolution, and more accurate, finerscale simulation of oil and gas reservoirs.
The growing accessibility and
adoption of reservoir modelling and
simulation on the more generalist
engineer’s desktop, has ensured
that the entire subsurface community can be involved in creating
these models and simulation runs,
rather than a few, highly specialist
reservoir engineers.
A Roxar customer, John
Campanella from Norwest Questa
Engineering Corp, put it well when
he said: “Personally, I think reservoir
simulation should be brought down
to every engineer’s desktop. We
need to push simulation out of the
back room and into the mainstream
where people can use it on a daily
basis.”
By adopting workflows and
tools that encourage this distributed-effort approach, organisations
are discovering that they can exploit
as yet untapped potential in their
workforce, involving non-specialist
disciplines and skill levels.
At a time when Booz Allen
Hamilton3 predicts that up to half of
the current workforce is likely to
retire within the next ten years, such
efficiencies and ‘democratisation’ of
the reservoir modelling process are
to be welcomed.
The importance of
workflow
Closely aligned to the rise in computing power is the importance of
workflow.
From seismic acquisition and
interpretation through to the building of a structural model, fault and
fracture modelling, history matching and simulation, it is an integrated, seamless and collaborative
workflow which provides the glue
to all activities.
Such a workflow is vital as a
repository for experience and
knowledge, for disseminating best
practices across global teams, and
helping new staff become proficient and efficient in their various
modelling roles.
A strong, IT-based workflow
simplifies the model building pro-
A B O U T
T H E
cess, ensures a high degree of quality control by coordinating inputs
and outputs and ensures transparency and accountability through the
generation of job sequences.
An easy to use interface is also
vital, which is why the latest Roxar
reservoir modelling software comes
with a new and modernised user
interface which resembles familiar,
everyday software applications.
This includes a task pane which
outlines the kind of tasks users are
likely to want to use at any given
point. Seeing what is relevant, as it
is required, enhances the user’s
sense of control, helps them maintain their own high standards, and
expands their range of experience
and competence.
A rapid model updating
workflow
Imagine a world where reservoir
models are kept evergreen as drilling data arrives, updating in realtime. New production data is
equally quickly assimilated through
continuous, computer assisted history matching.
The end result is a rapid model
updating workflow running on a
continuous basis as new production
data is gathered, ensuring the most
correct model is always available for
making important decisions about
the reservoir. This is what Roxar is
achieving today
At a time when the industry is
looking for fast, easy-to-use powerful reservoir management solutions to optimise production from
increasingly marginal assets, and
to make better decisions over the
allocation of capital and resources,
the timing could not have been
better. dewjournal.com
A U T H O R
Elizabeth Thompson is Technical Information Manager at
Roxar, responsible for ensuring that all technical information
is gathered and made available to the marketing and product
groups. Liz was formally product manager for Roxar’s fracture
modelling software and technical product manager for
Roxar’s structural geological tools.
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