7/22/2019 Advancing Reservoir Geomechanics Research for Unconventional Resources

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1 BACKGROUND/PURPOSE !

Rick Chalaturnyk, PhD, PEng!Reservoir Geomechanics Research Group [RG]2!University of Alberta!

Advancing Reservoir Geomechanics Research for Unconventional Resources!2 METHODOLOGY!

Foundation CMG Endowed Chair in Reservoir Geomechanics! Foundation CMG Industrial Research Chair in Reservoir Geomechanics for Unconventional Resources!

In contrast to conventional hydrocarbon reservoirs where flow in

the pore space dominates the physics of recovery, exploitation of

unconventional reservoirs typically involves recovery processes that

produce complex thermal, chemical and stress changes within the

reservoir that can significantly influence recovery. For oil sands reservoirs, the steam assisted gravity drainage (SAGD)

recovery process results not only in a complex interaction of

geomechanics and multiphase flow in primarily cohesionless porous

media (sand), but also in significant interactions with intra-formational

shale facies and shale dominated caprocks. The geomechanical

response of an oil sands reservoir to fluid pressure changes or to

temperature changes results in stress and deformations that affect

formation shearing, hydraulic properties such as absolute and relative

permeability, and the stability of underground openings. Temperature

increase causes thermal expansion of the sand grains and sand

structure, and pore pressure increase during steam injection decreases

the effective confining stress. For the anisotropic in situ stress state in

the reservoir, pore pressure will also generate shear stresses and shear

strains in the sand structure. These processes combine to result in a

net change in reservoir pore volume and permeability. For unconventional low permeability gas reservoirs (i.e. tight gas

sands, shale gas), production from either a conductive natural fracture

system or fracture system created from single or multi-stage hydraulic

fracturing is sensitive to the stress evolution accompanying drawdown

and depletion, which can cause fractures to close, reducing

permeability and creating challenges to sustaining economic flow rates.

While hydraulic fracturing has been in use for decades, understanding

relatively complex fracture systems consisting of both pre-existing and

newly created (by hydraulic stimulation) fractures remains a challenging

task, as the key mechanisms governing the interactions between the

propagating new fractures and the existing fracture network, and the

coupling between geomechanics and fluid dynamics, remains

unresolved. These fracture systems define reservoirs that upon

depletion will evolve mechanically over production time scales leading

to changes in fault behaviour, stress configuration, compaction and

ultimately, compartmentalization of the reservoir. Improved understanding of reservoir-geomechanical behaviour of

the oil sands, bitumen carbonates and bounding shale zones is critical

for the efficient, safe operation of these industrial projects and will also

assist in improving reservoir surveillance techniques and production

optimization activities. The IRC research program will create an environment where

reservoir geomechanics research for unconventional reservoirs will be

carried out in a sustained, coordinated and integrated fashion.

Independent but interrelated research projects developed in each step

of the workflow will enable research and fundamental knowledge to be

applied to solving a particular problem. Over the IRC research

program, research components encompass the full range of

unconventional hydrocarbon reservoirs, including oil sands, shale

caprocks, shale gas, coal (coalbed methane, enhanced coalbed methane

with CO2, underground gasification) and bitumen carbonates.

Fundamental Constitutive !Behaviour of Unconventional!Formations ! Characterization &Constitutive

Behavior of

Geomaterials

Reservoir

Geomechanical

Modeling

Field Scale

Reservoir

Geomechanics

Assessment of Reservoir ScaleProperties !

ReservoirGeomechanical Modelling !

Reservoir GeomechanicalResponses at Field Scale !

Multiphase Behavior of Oil Sands! Reservoir Geomechanical Characterization of Gas Shales! Intraformational and Caprock Shale Thermal Behavior! Reservoir Geomechanical Characterization of Bitumen Carbonates! Seismic Frequency Dynamic Properties! Constitutive Behavior of Thermal and Non-Thermal Oilfield Cements!

Upscaling Methodologies for Reservoir GeomechanicalModelling!

In Situ Stress Measurement: Techniques and Interpretation! Reservoir Geomechanical Pressuremeter! Physical Modelling to Verify Behaviour of

Discrete Fracture Network Models!

Adaptive Continuum/Discontinuum Modelling! Geomechanics and Geochemistry in

Streamline Simulations!

Thermal Well Integrity Assurance Modelling! Re-Analysis of Joslyn Creek Steam Release Incident! Integrated Well Designs for Reser voir Surveillance! Physical Modelling Studies for SAGD "! !Caprock Integrity!

Synthetic Rock

Mass

Geomechanics

Reservoir

Simulator

Discrete

Fracture

Network

Stress Path

Stress PathVolumetric Strain

PressureTemperatureGas Volume

PressureTemperatureGas Volume

Matrix Porosity

Fracture PorosityPermeability

Fracture PorosityPermeability

Mechanical PropertiesMicroseismicity IN

OUTDFN

IN

IN

IN

OUT

OUT

OUT

Deformation/Stress

Results

FluidFlow

DFN

Mechanical Properties

Digital

Fabrication! Exact scaled

representation of DFNs! Exact representation of

heterogeneity in core

specimens!

Collaborator Organization / Expertise

Dr. Mario Costa Sousa U of Calgary/Visualization/CMG ChairDr. David Dewhurst CISRO/Shale Laboratory WorkflowDr. Maurice Dusseault University of Waterloo/Petroleum GeomechanicsDr. Sebastian Geiger Heriot-Watt U/Carbonate Reservoirs/CMG ChairDr. Leonardo Guimaraes UFPE-Brazil/Geomechanics/CMG Chair