Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model
Enhanced geothermal system (EGS) is subject to the comprehensive effects of multiple physical fields during the long-term heat extraction process, including hydraulic (H), thermal (T), mechanical (M) and chemical (C) fields. The embedded discrete fracture model (EDFM) can effectively simulate the va...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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KeAi Communications Co., Ltd.
2023-10-01
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| Series: | Natural Gas Industry B |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352854023000670 |
| _version_ | 1797280655381364736 |
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| author | Dongxu Han Weitao Zhang Kaituo Jiao Bo Yu Tingyu Li Liang Gong Shurong Wang |
| author_facet | Dongxu Han Weitao Zhang Kaituo Jiao Bo Yu Tingyu Li Liang Gong Shurong Wang |
| author_sort | Dongxu Han |
| collection | DOAJ |
| description | Enhanced geothermal system (EGS) is subject to the comprehensive effects of multiple physical fields during the long-term heat extraction process, including hydraulic (H), thermal (T), mechanical (M) and chemical (C) fields. The embedded discrete fracture model (EDFM) can effectively simulate the variations of flow, temperature, mechanical and concentration fields in fractured reservoirs. At present, however, the thermo-hydro-mechanical-chemical (THMC) coupling model based on EDFM is less researched. In this paper, the THMC coupling model of fractured reservoir is established based on EDFM by considering the changes in reservoir heterogeneity and physical properties as well as water–rock reactions. Then, the spatiotemporal evolution of flow, temperature, displacement and concentration fields in the operation process of EGS is simulated and analyzed. And the following research results are obtained. First, when the permeability of the basement rock is low, the production temperature decrease during exploitation is gradual, allowing EGS to maintain a high exploitation temperature for an extended period. However, lower permeability may result in a decrease in the quality flow rate from production wells, thereby affecting net heat extraction power. Second, when fracture permeability or fracture opening changes, EGS can output higher temperature stably for a certain period and then the temperature decreases at different amplitudes. When the fracture permeability increases to a certain value or the fracture opening decreases to a certain value, the influence of the change in fracture parameters on production temperature gets weak. Third, After 40 years of EGS operation, considering variable property fluids results in a 22 °C lower exploitation temperature compared to using constant property fluids, and considering water–rock reactions results in a 15 °C lower exploitation temperature, with a 12.5 % increase in reservoir average porosity. In conclusion, when researching a long-term operating EGS, it is necessary to comprehensively consider the influences of reservoir rock parameters, physical properties of injected fluid, water–rock reaction and other factors. And in the future, attention shall be paid to the two-way coupling of chemical reaction and mechanical deformation of other mineral compositions in the reservoir to the hydro-thermo-chemical field influence, so as to provide more accurate and reliable prediction for the engineering development and utilization of EGS reservoirs. |
| first_indexed | 2024-03-07T16:43:26Z |
| format | Article |
| id | doaj.art-87b56ee56e5641fbbdf6db696818100c |
| institution | Directory Open Access Journal |
| issn | 2352-8540 |
| language | English |
| last_indexed | 2024-03-07T16:43:26Z |
| publishDate | 2023-10-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Natural Gas Industry B |
| spelling | doaj.art-87b56ee56e5641fbbdf6db696818100c2024-03-03T07:11:55ZengKeAi Communications Co., Ltd.Natural Gas Industry B2352-85402023-10-01105533546Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture modelDongxu Han0Weitao Zhang1Kaituo Jiao2Bo Yu3Tingyu Li4Liang Gong5Shurong Wang6School of Mechanical Engineering, Beijing University of Petrochemical Technology, Beijing 102617, China; Corresponding author.School of New Energy, China University of Petroleum (East China), Qingdao, Shandong 266580, ChinaState Key Laboratory of Power Engineering Multiphase, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, ChinaSchool of Mechanical Engineering, Beijing University of Petrochemical Technology, Beijing 102617, ChinaLow-Speed Aerodynamics Research Institute, China Aerodynamics Research and Development Center, Chengdu, Sichuan 621050, ChinaSchool of New Energy, China University of Petroleum (East China), Qingdao, Shandong 266580, ChinaState Key Laboratory of Efficient and Clean Energy Utilization, Zhejiang University, Hangzhou, Zhejiang 310058, ChinaEnhanced geothermal system (EGS) is subject to the comprehensive effects of multiple physical fields during the long-term heat extraction process, including hydraulic (H), thermal (T), mechanical (M) and chemical (C) fields. The embedded discrete fracture model (EDFM) can effectively simulate the variations of flow, temperature, mechanical and concentration fields in fractured reservoirs. At present, however, the thermo-hydro-mechanical-chemical (THMC) coupling model based on EDFM is less researched. In this paper, the THMC coupling model of fractured reservoir is established based on EDFM by considering the changes in reservoir heterogeneity and physical properties as well as water–rock reactions. Then, the spatiotemporal evolution of flow, temperature, displacement and concentration fields in the operation process of EGS is simulated and analyzed. And the following research results are obtained. First, when the permeability of the basement rock is low, the production temperature decrease during exploitation is gradual, allowing EGS to maintain a high exploitation temperature for an extended period. However, lower permeability may result in a decrease in the quality flow rate from production wells, thereby affecting net heat extraction power. Second, when fracture permeability or fracture opening changes, EGS can output higher temperature stably for a certain period and then the temperature decreases at different amplitudes. When the fracture permeability increases to a certain value or the fracture opening decreases to a certain value, the influence of the change in fracture parameters on production temperature gets weak. Third, After 40 years of EGS operation, considering variable property fluids results in a 22 °C lower exploitation temperature compared to using constant property fluids, and considering water–rock reactions results in a 15 °C lower exploitation temperature, with a 12.5 % increase in reservoir average porosity. In conclusion, when researching a long-term operating EGS, it is necessary to comprehensively consider the influences of reservoir rock parameters, physical properties of injected fluid, water–rock reaction and other factors. And in the future, attention shall be paid to the two-way coupling of chemical reaction and mechanical deformation of other mineral compositions in the reservoir to the hydro-thermo-chemical field influence, so as to provide more accurate and reliable prediction for the engineering development and utilization of EGS reservoirs.http://www.sciencedirect.com/science/article/pii/S2352854023000670Enhanced geothermal systemEmbedded discrete fracture modelTHMC coupling modelFractured reservoirWater-rock reactionHeat extraction |
| spellingShingle | Dongxu Han Weitao Zhang Kaituo Jiao Bo Yu Tingyu Li Liang Gong Shurong Wang Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model Natural Gas Industry B Enhanced geothermal system Embedded discrete fracture model THMC coupling model Fractured reservoir Water-rock reaction Heat extraction |
| title | Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| title_full | Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| title_fullStr | Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| title_full_unstemmed | Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| title_short | Thermal‒hydraulic‒mechanical‒chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| title_sort | thermal hydraulic mechanical chemical coupling analysis of enhanced geothermal systems based on an embedded discrete fracture model |
| topic | Enhanced geothermal system Embedded discrete fracture model THMC coupling model Fractured reservoir Water-rock reaction Heat extraction |
| url | http://www.sciencedirect.com/science/article/pii/S2352854023000670 |
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