U N I V E R S I T E T E T
I
B E R G E N
Department of Earth Science
ANIGMA
An Integrated Geological and Mathematical Framework for the
Characterization, Modelling and Simulation of Fractured Geothermal
Reservoirs
Atle Rotevatn, Eirik Keilegavlen, Eivind Bastesen, Inga Berre, Simon
Buckley, Casey Nixon, John Howell, David Sanderson, Pål Næverlid
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Det matematisk-naturvitenskapelige fakultet
Image source: bpa.gov
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Representation
injector
producer
Sandve et. al. 2012
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Simulating fluid flow (and heat extraction!)
• Need to capture geological detail
• Need to capture flow properties of fracture network
• Need to solve the right equations…
Fractures
Upscaled
Exact
Sandve et. al. 2013
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Fracture data for geology and simulation
• Traditional simulators: Represent flow properties by
averaged parameters
– Not beneficial for characterization nor simulation
– HOWEVER: preserving geological detail is
computationally expensive
– WHAT are we really after?
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Some key challenges summarized
• Unclear which set of fracture parameters that provide the
most direct route to realistically predicting flow
properties.
• Computationally efficient simulation tools that also
preserve a necessary level of geological detail (e.g.
fractures) are still to be developed
• The above points can only be addressed by combining
advancement within characterization and simulation of
fractured media
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Rationale // Project philosophy
Reservoir
Characterization
Geological characterization of
reservoir rocks and fractures
Reservoir
modelling
Representation of
geological structures
in a grid
Feedback loop
Flow simulation
Numerical simulation
of energy extraction
ANIGMA
Project aims // Iterative, integrated task flow chart
Simulate energy extraction / flow
Select site, revise data
collection strategy
Main aim of project: develop fully integrated
geo-math approach to the characterization,
modelling and simulation of fractured
geothermal basement reservoirs.
Collect fracture
data (digital and
traditional)
Design grid / represent fractures
Characterize fracture network topology
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Geometry and Topology
Geometry
• measurable elements
• orientation and size of lines,
planar surfaces etc.
• units and dimensions
Topology
• relationships between elements
• invariant with strain and scale
• relates to “connectivity”
• dimensionless
Topologist –
mathematician who can not tell difference between a coffee cup and a donut.
Node and Branch Model
Sanderson and Nixon
2015, JSG
Nodes
• We consider a fracture
network in terms of
Nodes and Branches
between Nodes
Follows approach from
Manzocchi 2002, WRR
Branches
I‐node fault tip
I‐I
isolated branch
Y‐node abutments/splays
I‐C
“dangling end”
X‐node crossing faults
C‐C
“fully connected”
Triangles and
Parameters
•
Number counts of each
node and branch type
•
Plot proportions in ternary
diagrams
A
B
Nixon 2013, Thesis
•
Extract dimensionless
parameters from node
counts:
connections
per branch

connections
per branch
(3NY  4NX )
NB
Branches
Nodes
Sanderson and Nixon
2015, JSG
Why is topology important?
Geometry same
Sets
A=B
Number
A=B
Intensity
A=B
Mean length A = B
A – natural fracture
network
Sanderson and Nixon
2015, JSG
B – stochastic model
Topology different
Backbone
A>B
Connectivity A > B
Flow
A>B
I
B
Connectivity and Flow
depend on Topology
A
Y
X
How can we ignore
TOPOLOGY, e.g. use
stochastic models?
Research questions in ANIGMA:
If detailed information on fractures on ‘all’ scales is available to the simulation model:
• Which parameters are best suited to describe flow properties of a fracture network? • Which information can be upscaled, which should be preserved?
• What is a meaningful accuracy in geological data and simulation results? • Can simulations be used as a screening tool to determine which data to collect?
Deliverables:
• New workflows for integrated data collection, modelling and simulation
• New numerical methods
ANIGMA
An Integrated Geological and Mathematical Framework for the Characterization,
Modelling and Simulation of Fractured Geothermal Reservoirs
PI Prof. Atle Rotevatn
Dept. of Earth Science, UiB
Co-I Dr. Simon Buckley
Uni CIPR
PI Dr. Eirik Keilegavlen
Dept. of Mathematics, UiB
Dr. Casey Nixon
Dept. of Earth Science,
UiB
PI Prof. Inga Berre
Dept. of Mathematics, UiB
Dr. Pål Næverlid
Dept. of Mathematics,
UiB
Prof. John Howell
University of Aberdeen
PI Dr. Eivind Bastesen
Uni Research CIPR
Prof. David Sanderson
University of
Southampton
Funding
• 9.8 MNOK
• 80% RCN – ENERGIX program
• 20% Statoil through “Akademia‐agreement”
• 3.5 years, started mid‐2015
• Thanks for your attention
• Extra material
Det matematisk-naturvitenskapelige fakultet
Selected research projects
Geothermal projects
POGE (2009-2013)
Modeling and simulation of energy extraction from enhanced geothermal systems
Funding: approx. 9 MNOK (RCN, Statoil-Akademia)
GeoStim (2014-2017)
Mathematical modeling and simulation of fracture opening in geothermal reservoirs
Funding: 7 MNOK (RCN, BKK, Statoil-Akademia)
Ustip (2012-2013)
Analysis of flow and heat transport in porous media
Funding: 2.7 MNOK (UiB)
ANIGMA (2015-2018)
An Integrated Geological and Mathematical Framework for the Characterization,
Modeling and Simulation of Fractured Geothermal Reservoirs
Funding: 9.6 MNOK (RCN, Statoil-Akademia)
Other relevant project activity with support from Statoilakademia
PROTECT (2014-2017)
Protection of caprock integrity for large-scale CO2-storage
CFRAC (2012-2015)
Characterization of naturally fractured reservoirs
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