Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification
The evolution of fracture zone controls the safety of underground coal gasification (UCG) in terms of gas emission and water leakage. In order to understand the fracture propagation in the confining rock of a UCG cavity with various influence factors, this paper implemented a set of numerical models...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-10-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/15/19/7373 |
| _version_ | 1797479396751179776 |
|---|---|
| author | Zhen Dong Haiyang Yi Yufeng Zhao Xinggang Wang Tingxiang Chu Junjie Xue Hanqi Wu Shanshan Chen Mengyuan Zhang Hao Chen |
| author_facet | Zhen Dong Haiyang Yi Yufeng Zhao Xinggang Wang Tingxiang Chu Junjie Xue Hanqi Wu Shanshan Chen Mengyuan Zhang Hao Chen |
| author_sort | Zhen Dong |
| collection | DOAJ |
| description | The evolution of fracture zone controls the safety of underground coal gasification (UCG) in terms of gas emission and water leakage. In order to understand the fracture propagation in the confining rock of a UCG cavity with various influence factors, this paper implemented a set of numerical models based on different geological and operating conditions. Analysis was implemented on the mechanism of fracture propagation and its evolution characteristics, suggesting that (a) continuum expansion of the cavity leads a near-field fracture circle in confining rock initially, followed by the roof caving and successive propagation of shear band. (b) The key observed influence factors of fracture propagation are the grade of confining rock, overburden pressure, dimension of the cavity and gasifying pressure, the linear relationships between them, and the fracture height. Additionally, the fracture depth in the base board was mainly caused by tensile fracture. (c) A model was proposed based on the evolution of fracture height and depth in roof and base board, respectively. Validation of this model associated with orthogonal tests suggests a good capacity for predicting fracture distribution. This paper has significance in guiding the design of the gasifying operation and safety assessment of UCG cavities. |
| first_indexed | 2024-03-09T21:46:16Z |
| format | Article |
| id | doaj.art-a91110f8b70d4b73a730d7eb3eaa5b82 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-09T21:46:16Z |
| publishDate | 2022-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-a91110f8b70d4b73a730d7eb3eaa5b822023-11-23T20:17:56ZengMDPI AGEnergies1996-10732022-10-011519737310.3390/en15197373Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal GasificationZhen Dong0Haiyang Yi1Yufeng Zhao2Xinggang Wang3Tingxiang Chu4Junjie Xue5Hanqi Wu6Shanshan Chen7Mengyuan Zhang8Hao Chen9Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaNorth China Institute of Science and Technology, Langfang 065201, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina Tuha Oilfield Company, Hami 839009, ChinaNorth China Institute of Science and Technology, Langfang 065201, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaPetroChina Gas Storage Company, Beijing 100101, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, ChinaThe evolution of fracture zone controls the safety of underground coal gasification (UCG) in terms of gas emission and water leakage. In order to understand the fracture propagation in the confining rock of a UCG cavity with various influence factors, this paper implemented a set of numerical models based on different geological and operating conditions. Analysis was implemented on the mechanism of fracture propagation and its evolution characteristics, suggesting that (a) continuum expansion of the cavity leads a near-field fracture circle in confining rock initially, followed by the roof caving and successive propagation of shear band. (b) The key observed influence factors of fracture propagation are the grade of confining rock, overburden pressure, dimension of the cavity and gasifying pressure, the linear relationships between them, and the fracture height. Additionally, the fracture depth in the base board was mainly caused by tensile fracture. (c) A model was proposed based on the evolution of fracture height and depth in roof and base board, respectively. Validation of this model associated with orthogonal tests suggests a good capacity for predicting fracture distribution. This paper has significance in guiding the design of the gasifying operation and safety assessment of UCG cavities.https://www.mdpi.com/1996-1073/15/19/7373underground coal gasificationfracture evolutioncavity expansionsafety assessmentgas emissionwater leakage |
| spellingShingle | Zhen Dong Haiyang Yi Yufeng Zhao Xinggang Wang Tingxiang Chu Junjie Xue Hanqi Wu Shanshan Chen Mengyuan Zhang Hao Chen Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification Energies underground coal gasification fracture evolution cavity expansion safety assessment gas emission water leakage |
| title | Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification |
| title_full | Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification |
| title_fullStr | Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification |
| title_full_unstemmed | Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification |
| title_short | Investigation of the Evolution of Stratum Fracture during the Cavity Expansion of Underground Coal Gasification |
| title_sort | investigation of the evolution of stratum fracture during the cavity expansion of underground coal gasification |
| topic | underground coal gasification fracture evolution cavity expansion safety assessment gas emission water leakage |
| url | https://www.mdpi.com/1996-1073/15/19/7373 |
| work_keys_str_mv | AT zhendong investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT haiyangyi investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT yufengzhao investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT xinggangwang investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT tingxiangchu investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT junjiexue investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT hanqiwu investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT shanshanchen investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT mengyuanzhang investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification AT haochen investigationoftheevolutionofstratumfractureduringthecavityexpansionofundergroundcoalgasification |