Advancing Reservoir Geomechanics Research for Unconventional Resources

Advancing Reservoir Geomechanics Research for Unconventional Resources! Reservoir Geomechanics Research Group [RG]2! University of Alberta!

1 BACKGROUND/PURPOSE !

2 METHODOLOGY!

Fundamental Constitutive Behaviour of Unconventional !Formations !

! Characterization & Constitutive Behavior of Geomaterials

•  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!

Assessment of Reservoir Scale Properties ! •  Upscaling Methodologies for Reservoir Geomechanical Modelling! •  In Situ Stress Measurement: Techniques and Interpretation! •  Reservoir Geomechanical Pressuremeter! •  Physical Modelling to Verify Behaviour of Discrete Fracture Network Models!

Digital Fabrication! •  Exact scaled representation of DFN’s! •  Exact representation of heterogeneity in core specimens!

Reservoir Geomechanical Responses at Field Scale !

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

Field Scale Reservoir Geomechanics

Reservoir Geomechanical Modelling ! •  Adaptive Continuum/Discontinuum Modelling! •  Geomechanics and Geochemistry in Streamline Simulations! Deformation/Stress

Geomechanics

OUT

Stress Path Volumetric Strain

Pressure Temperature OUT Gas Volume

Synthetic Rock Mass OUT

Mechanical Properties Δ DFN

IN

Reservoir Simulator Discrete Fracture Network Results

Organization / Expertise U of Calgary/Visualization/CMG Chair CISRO/Shale Laboratory Workflow University of Waterloo/Petroleum Geomechanics Heriot-Watt U/Carbonate Reservoirs/CMG Chair UFPE-Brazil/Geomechanics/CMG Chair

IN

Pressure Temperature Gas Volume Mechanical Properties

IN Stress Path

Δ DFN

Collaborator Dr. Mario Costa Sousa Dr. David Dewhurst Dr. Maurice Dusseault Dr. Sebastian Geiger Dr. Leonardo Guimaraes

Reservoir Geomechanical Modeling

Matrix Porosity Fracture Porosity IN Permeability OUT Fracture Porosity Permeability

Fluid Flow

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.

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

Microseismicity

Rick Chalaturnyk, PhD, PEng!