An Integrated Geomechanics Workflow for Caprock-Integrity Analysis of a Potential Carbon Storage

Khan, Shakil Ahamed; Han, Hongxue; Ansari, Sajjad Ahmed; Khosravi, Nader

doi:10.2118/139477-ms

Cited by 19 publications

(6 citation statements)

References 4 publications

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“…The subsequent increase in pore pressure results in a reduction of effective stress. At low confining pressures, the shear strength of rock drops significantly because of effective-stress reduction (Handin and Hager 1957), which may lead to inadvertent hydraulic fracturing within the reservoir (Khan et al 2010(Khan et al , 2011. In severe scenarios, an effective-stress reduction to zero may result in liquefaction or a complete loss of shear strength.…”

Section: Caprock Integrity In Sagd and Em-sagd Projectsmentioning

confidence: 99%

Evaluation of Induced Thermal Pressurization in Clearwater Shale Caprock in Electromagnetic Steam-Assisted Gravity-Drainage Projects

2013

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Inductive methods, such as electromagnetic steam-assisted gravity drainage (EM-SAGD), have been identified as technically and economically feasible recovery methods for shallow oil-sands reservoirs with overburdens of more than 30 m (Koolman et al. 2008). However, in EM-SAGD projects, the caprock overlying oil-sands reservoirs is also electromagnetically heated along with the bitumen reservoir. Because permeability is low in Alberta thermal-project caprock formations (i.e., the Clearwater shale formation in the Athabasca deposit and the Colorado shale formation in the Cold Lake deposit), the pore pressure resulting from the thermal expansion of pore fluids may not be balanced with the fluid loss caused by flow and the fluid-volume changes resulting from pore dilation. In extreme cases, the water boils, and the pore pressure increases dramatically as a result of the phase change in the water, which causes profound effective-stress reduction. After this condition is established, pore pressure increases can lead to shear failure of the caprock, the creation of microcracks and hydraulic fractures, and subsequent caprock integrity failure. It is typically believed that low-permeability caprocks impede the transmission of pore pressure from the reservoir, making them more resistant to shear failure (Collins 2005(Collins , 2007. In cases of induced thermal pressurization, low-permeability caprocks are not always more resistant. In this study, analytical solutions are obtained for temperature and pore-pressure rises caused by the constant EM heating rate of the caprock. These analytical solutions show that pore-pressure increases from EM heating depend on the permeability and compressibility of the caprock formation. For stiff or low-compressibility media, thermal pressurization can cause fluid pressures to approach hydrostatic pressure, and shear strength to approach zero for low-cohesive-strength units of the caprock (units of the caprock with high silt and sand percentage) and sections of the caprock with pre-existing fractures with no cohesion. IntroductionOf Canada's 179 billion bbl of oil reserves, Alberta's oil sand contains 170.4 billion bbl of those oil reserves (Government of Alberta 2011, 2012, and with the recent increase in demand, tremendous efforts are being made to develop bitumen reservoirs in the coming decades. SAGD is one successful thermal-recovery technique applied to the oil sands of Alberta, Canada. Approximately 80% of the oil sands are recoverable through in-situ production (i.e., they lie at a depth of 75 to 750 m with an average seam thickness of less than 20 m), with only 20% recoverable by mining (i.e., they lie at a depth of 75 m or less with an average seam thickness of 32 m) (Vermeulen and Chute 1983; Government of Alberta 2008).

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Section: Caprock Integrity In Sagd and Em-sagd Projectsmentioning

confidence: 99%

Evaluation of Induced Thermal Pressurization in Clearwater Shale Caprock in Electromagnetic Steam-Assisted Gravity-Drainage Projects

2013

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“…Li et al, 2006;Liu et al, 2020;K. Zhang, Liu, & Huang, 2020), formation failure (Arfaee & Sola, 2014;Khan et al, 2010;Vilarrasa et al, 2019;Vilarrasa & Carrera, 2015;Z. Zhang, Jiang, et al, 2019), leakage through fractures or faults (Miocic et al, 2016;Nakajima et al, 2014) and well damage (Bai et al, 2016;Carroll et al, 1998;Iyer et al, 2022;Miyazaki, 2009;Ugarte & Salehi, 2022).…”

Section: Introductionmentioning

confidence: 99%

Assessing Subsurface Gas Storage Security for Climate Change Mitigation and Energy Transition

Pan,

Jin,

et al. 2024

Geophysical Research Letters

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Subsurface gas storage is crucial for achieving a sustainable energy future, as it helps to reduce CO2 emissions and facilitates the provision of renewable energy sources. The confinement effect of the nanopores in caprock induces distinctive thermophysical properties and fluid dynamics. In this paper, we present a multi‐scale study to characterize the subsurface transport of CO2, CH4, and H2. A nanoscale‐extended volume‐translated Cubic‐Plus‐Association equation of state was developed and incorporated in a field‐scale numerical simulation, based on a full reservoir‐caprock suite model. Results suggest that in the transition from nanoscale to bulk‐scale, gas solubility in water decreases while phase density and interfacial tension increase. For the first time, a power law relationship was identified between the capillary pressure within nanopores and the pore size. Controlled by buoyancy, viscous force and capillary pressure, gases transport vertically and horizontally in reservoir and caprock. H2 has the maximum potential to move upward and the lowest areal sweep efficiency; in short term, CH4 is more prone to upward migration compared to CO2, while in long term, CH4 and CO2 perform comparably. Thicker caprock and larger caprock pore size generally bring greater upward inclination. Gases penetrate the caprock when CH4 is stored with a caprock thickness smaller than 28 m or H2 is stored with a caprock pore size of 2–10 nm or larger than 100 nm. This study sheds light on the fluid properties and dynamics in nanoconfined environment and is expected to contribute to the safe implementation of gigatonne scale subsurface gas storage.

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“…To account for coupled THM processes in fractured and porous rocks under multiphase condition, and linked TOUGH2 with FLAC3D to investigate the stress changes and potential fault slip by CO 2 -injection in saline aquifers. Khan et al (2010) integrated VISAGE and ECLIPSE to investigate the caprock integrity of a potential carbon storage site and Ouellet et al (2011) use this coupled code to simulate the CO 2 injection in saline aquifer at Ketzin, Germany. Li and Li (2010) linked FLAC to CMG's GEM to study the CO 2 enhanced coal bed methane (ECBM) recovery.…”

Section: Introductionmentioning

confidence: 99%

Thermo-hydro-mechanical modeling of carbon dioxide injection for enhanced gas-recovery (CO2-EGR): a benchmarking study for code comparison

et al. 2012

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The objective of this paper was to investigate the THM-coupled responses of the storage formation and caprock, induced by gas production, CO 2 -EGR (enhanced gas recovery), and CO 2 -storage. A generic 3D planer model (20,000 9 3,000 9 100 m, consisting of 1,200 m overburden, 100 m caprock, 200 m gas reservoir, and 1,500 m base rock) is adopted for the simulation process using the integrated code TOUGH2/EOS7C-FLAC3D and the multi-purpose simulator OpenGeoSys. Both simulators agree that the CO 2 -EGR phase under a balanced injection rate (31,500 tons/year) will cause almost no change in the reservoir pressure. The gas recovery rate increases 1.4 % in the 5-year CO 2 -EGR phase, and a better EGR effect could be achieved by increasing the distance between injection and production wells (e.g., 5.83 % for 5 km distance, instead of 1.2 km in this study). Under the considered conditions there is no evidence of plastic deformation and both reservoir and caprock behave elastically at all operation stages. The stress path could be predicted analytically and the results show that the isotropic and extensional stress regime will switch to the compressional stress regime, when the pore pressure rises to a specific level. Both simulators agree regarding modification of the reservoir stress state. With further CO 2 -injection tension failure in reservoir could occur, but shear failure will never happen under these conditions. Using TOUGH-FLAC, a scenario case is also analyzed with the assumption that the reservoir is naturally fractured. The specific analysis shows that the maximal storage pressure is 13.6 MPa which is determined by the penetration criterion of the caprock.

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An Integrated Geomechanics Workflow for Caprock-Integrity Analysis of a Potential Carbon Storage

Cited by 19 publications

References 4 publications

Evaluation of Induced Thermal Pressurization in Clearwater Shale Caprock in Electromagnetic Steam-Assisted Gravity-Drainage Projects

Evaluation of Induced Thermal Pressurization in Clearwater Shale Caprock in Electromagnetic Steam-Assisted Gravity-Drainage Projects

Assessing Subsurface Gas Storage Security for Climate Change Mitigation and Energy Transition

Thermo-hydro-mechanical modeling of carbon dioxide injection for enhanced gas-recovery (CO2-EGR): a benchmarking study for code comparison

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