Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development
Stress changes associated with reservoir depletion have been frequently observed. Stress evolution within and around the drainage areas can affect the completion of infill wells and refracturing considerably. To accurately predict the stress distribution in shale gas reservoirs, a coupled fluid-flow...
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KeAi Communications Co., Ltd.
2025-02-01
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| Series: | Petroleum |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405656124000099 |
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| author | Qiang Wang Yufeng Wang Rong Wang Jinzhou Zhao Yongquan Hu Jin Zhao |
| author_facet | Qiang Wang Yufeng Wang Rong Wang Jinzhou Zhao Yongquan Hu Jin Zhao |
| author_sort | Qiang Wang |
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| description | Stress changes associated with reservoir depletion have been frequently observed. Stress evolution within and around the drainage areas can affect the completion of infill wells and refracturing considerably. To accurately predict the stress distribution in shale gas reservoirs, a coupled fluid-flow/geomechanics model considering the microscopic seepage mechanism of shale gas and the distribution of complex natural fractures (NFs) was derived based on Biot's theory, the embedded discrete fracture model, and the finite volume method. Based on this model, stress can be predicted by considering the mechanisms of adsorption, desorption, diffusion, and slippage of shale gas and the random distribution of NFs. The results show that in the process of stress evolution, there will be extremes of σxx, σyy, σxy, Δσ, α, and stress reversal area at a certain point, and the time of occurrence of extremes differs at different positions. The key to determining this law is the pore pressure gradient, with a spatiotemporal evolution effect. Different microscopic seepage mechanisms significantly influence the storage and transmission of shale gas, leading to significant differences in the distributions of reservoir pressure and stress. The larger the initial stress difference, the more difficult the stress reversal. When the initial stress difference exceeds a certain limit, stress reversal does not occur in the reservoir. Under the influence of the distribution difference of the NFs, the shape of the pressure-depletion area and magnitude of the pressure gradient differed significantly. As the approaching angle of NFs increased, the range of stress reversal in the top and bottom parts of the domain gradually decreases; At the same time, the orientation of maximum horizontal stress (MHS) near the fractures also gradually decreases. When the approaching angles of the NFs are the same, the number of natural fractures has little effect on the stress. Owing to the effect of NFs and hydraulic fracture, the anisotropy of stress is enhanced, the occurrence time of extreme value of local stress and stress reversal area differ significantly, and selecting the timing of infill well fracturing and refracturing becomes difficult. This research is essential to understanding the stress evolution law of shale gas reservoirs and guiding the completion of infill wells and refracturing design. |
| format | Article |
| id | doaj-art-d60c43d149204b2fa98d9eb06f287a8c |
| institution | OA Journals |
| issn | 2405-6561 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | KeAi Communications Co., Ltd. |
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| series | Petroleum |
| spelling | doaj-art-d60c43d149204b2fa98d9eb06f287a8c2025-08-20T02:02:05ZengKeAi Communications Co., Ltd.Petroleum2405-65612025-02-01111718310.1016/j.petlm.2024.04.001Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well developmentQiang Wang0Yufeng Wang1Rong Wang2Jinzhou Zhao3Yongquan Hu4Jin Zhao5State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610500, China; Corresponding author.State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610500, ChinaDownhole Technology Company, CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu 610051, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610500, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610500, China; School of Mechanical Engineering, Yangtze University, Jingzhou 434023, ChinaStress changes associated with reservoir depletion have been frequently observed. Stress evolution within and around the drainage areas can affect the completion of infill wells and refracturing considerably. To accurately predict the stress distribution in shale gas reservoirs, a coupled fluid-flow/geomechanics model considering the microscopic seepage mechanism of shale gas and the distribution of complex natural fractures (NFs) was derived based on Biot's theory, the embedded discrete fracture model, and the finite volume method. Based on this model, stress can be predicted by considering the mechanisms of adsorption, desorption, diffusion, and slippage of shale gas and the random distribution of NFs. The results show that in the process of stress evolution, there will be extremes of σxx, σyy, σxy, Δσ, α, and stress reversal area at a certain point, and the time of occurrence of extremes differs at different positions. The key to determining this law is the pore pressure gradient, with a spatiotemporal evolution effect. Different microscopic seepage mechanisms significantly influence the storage and transmission of shale gas, leading to significant differences in the distributions of reservoir pressure and stress. The larger the initial stress difference, the more difficult the stress reversal. When the initial stress difference exceeds a certain limit, stress reversal does not occur in the reservoir. Under the influence of the distribution difference of the NFs, the shape of the pressure-depletion area and magnitude of the pressure gradient differed significantly. As the approaching angle of NFs increased, the range of stress reversal in the top and bottom parts of the domain gradually decreases; At the same time, the orientation of maximum horizontal stress (MHS) near the fractures also gradually decreases. When the approaching angles of the NFs are the same, the number of natural fractures has little effect on the stress. Owing to the effect of NFs and hydraulic fracture, the anisotropy of stress is enhanced, the occurrence time of extreme value of local stress and stress reversal area differ significantly, and selecting the timing of infill well fracturing and refracturing becomes difficult. This research is essential to understanding the stress evolution law of shale gas reservoirs and guiding the completion of infill wells and refracturing design.http://www.sciencedirect.com/science/article/pii/S2405656124000099Shale gas reservoirStressEmbedded discrete fracture modelMicroscopic seepage mechanismCoupled fluid-flow/geomechanics |
| spellingShingle | Qiang Wang Yufeng Wang Rong Wang Jinzhou Zhao Yongquan Hu Jin Zhao Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development Petroleum Shale gas reservoir Stress Embedded discrete fracture model Microscopic seepage mechanism Coupled fluid-flow/geomechanics |
| title | Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development |
| title_full | Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development |
| title_fullStr | Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development |
| title_full_unstemmed | Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development |
| title_short | Evolution law of stress induced by pressure depletion in fractured shale reservoirs: Implications for subsequent refracturing and infill well development |
| title_sort | evolution law of stress induced by pressure depletion in fractured shale reservoirs implications for subsequent refracturing and infill well development |
| topic | Shale gas reservoir Stress Embedded discrete fracture model Microscopic seepage mechanism Coupled fluid-flow/geomechanics |
| url | http://www.sciencedirect.com/science/article/pii/S2405656124000099 |
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