Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam
To reveal the evolution law of coal skeleton deformation during the process of CO2 flooding and displacing CH4 in coal seam, a fluid-solid coupling mathematical model of CO2 injection enhanced CH4 drainage was established based on Fick’s law, Darcy’s law, ideal gas state equation, and Langmuir equat...
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| Format: | Article |
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Frontiers Media S.A.
2021-10-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2021.766011/full |
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| author | Chaojun Fan Chaojun Fan Lei Yang Gang Wang Qiming Huang Xiang Fu Haiou Wen |
| author_facet | Chaojun Fan Chaojun Fan Lei Yang Gang Wang Qiming Huang Xiang Fu Haiou Wen |
| author_sort | Chaojun Fan |
| collection | DOAJ |
| description | To reveal the evolution law of coal skeleton deformation during the process of CO2 flooding and displacing CH4 in coal seam, a fluid-solid coupling mathematical model of CO2 injection enhanced CH4 drainage was established based on Fick’s law, Darcy’s law, ideal gas state equation, and Langmuir equation. Meanwhile, numerical simulations were carried out by implementing the mathematical model in the COMSOL Multiphysics. Results show that the CH4 content of both regular gas drainage and CO2 enhanced gas drainage gradually decreases with time, and the decreasing rate is high between 10 and 60 days. Compared with regular gas drainage, the efficiency of CO2 enhanced gas drainage is more obvious with greater amount of CH4 extracted out. When coal seam gas is extracted for 10, 60, 120, and 180 days, CH4 content in coal seam is reduced by 5.2, 17.2, 23.6, and 26.7%, respectively. For regular gas drainage, the deformation of coal skeleton is dominated by the shrink of coal matrix induced by gas desorption, and the strain curve shows a continuous downward trend. For CO2 enhanced gas drainage, the strain curve of coal skeleton showed a decrease—rapid increase—slow increase trend. The evolution of permeability is opposite to the evolution of coal skeleton strain. Higher gas injection pressure will lead to a greater coal skeleton strain. The pumping pressure affects the deformation of coal skeleton slightly compared with that of initial water saturation and initial temperature. Greater initial water saturation leads to larger deformation of coal skeleton in the early stage. The strain value of coal skeleton gradually tends to be consistent as gas injection prolongs. Higher initial temperature leads to greater reduction in coal skeleton strain when the gas injection continues. Research achievements provide a basis for the field application of CO2 injection enhanced CH4 drainage in underground coal mines. |
| first_indexed | 2024-12-22T08:34:10Z |
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| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-22T08:34:10Z |
| publishDate | 2021-10-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Earth Science |
| spelling | doaj.art-4c9b298a8aed4fa5ac8cf31463a57d1c2022-12-21T18:32:24ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632021-10-01910.3389/feart.2021.766011766011Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal SeamChaojun Fan0Chaojun Fan1Lei Yang2Gang Wang3Qiming Huang4Xiang Fu5Haiou Wen6College of Mining, Liaoning Technical University, Fuxin, ChinaKey Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, ChinaCollege of Mining, Liaoning Technical University, Fuxin, ChinaKey Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, ChinaKey Laboratory of Mining Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao, ChinaCollege of Mining, Liaoning Technical University, Fuxin, ChinaCollege of Mining, Liaoning Technical University, Fuxin, ChinaTo reveal the evolution law of coal skeleton deformation during the process of CO2 flooding and displacing CH4 in coal seam, a fluid-solid coupling mathematical model of CO2 injection enhanced CH4 drainage was established based on Fick’s law, Darcy’s law, ideal gas state equation, and Langmuir equation. Meanwhile, numerical simulations were carried out by implementing the mathematical model in the COMSOL Multiphysics. Results show that the CH4 content of both regular gas drainage and CO2 enhanced gas drainage gradually decreases with time, and the decreasing rate is high between 10 and 60 days. Compared with regular gas drainage, the efficiency of CO2 enhanced gas drainage is more obvious with greater amount of CH4 extracted out. When coal seam gas is extracted for 10, 60, 120, and 180 days, CH4 content in coal seam is reduced by 5.2, 17.2, 23.6, and 26.7%, respectively. For regular gas drainage, the deformation of coal skeleton is dominated by the shrink of coal matrix induced by gas desorption, and the strain curve shows a continuous downward trend. For CO2 enhanced gas drainage, the strain curve of coal skeleton showed a decrease—rapid increase—slow increase trend. The evolution of permeability is opposite to the evolution of coal skeleton strain. Higher gas injection pressure will lead to a greater coal skeleton strain. The pumping pressure affects the deformation of coal skeleton slightly compared with that of initial water saturation and initial temperature. Greater initial water saturation leads to larger deformation of coal skeleton in the early stage. The strain value of coal skeleton gradually tends to be consistent as gas injection prolongs. Higher initial temperature leads to greater reduction in coal skeleton strain when the gas injection continues. Research achievements provide a basis for the field application of CO2 injection enhanced CH4 drainage in underground coal mines.https://www.frontiersin.org/articles/10.3389/feart.2021.766011/fullcoal seamCO2 injection enhanced CH4 drainagecoal skeleton deformationnumerical simulationfluid-solid coupling model |
| spellingShingle | Chaojun Fan Chaojun Fan Lei Yang Gang Wang Qiming Huang Xiang Fu Haiou Wen Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam Frontiers in Earth Science coal seam CO2 injection enhanced CH4 drainage coal skeleton deformation numerical simulation fluid-solid coupling model |
| title | Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam |
| title_full | Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam |
| title_fullStr | Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam |
| title_full_unstemmed | Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam |
| title_short | Investigation on Coal Skeleton Deformation in CO2 Injection Enhanced CH4 Drainage From Underground Coal Seam |
| title_sort | investigation on coal skeleton deformation in co2 injection enhanced ch4 drainage from underground coal seam |
| topic | coal seam CO2 injection enhanced CH4 drainage coal skeleton deformation numerical simulation fluid-solid coupling model |
| url | https://www.frontiersin.org/articles/10.3389/feart.2021.766011/full |
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