Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States
Shale gas can be commercially produced using the stimulated reservoir volume (SRV) with multistage fracturing or multiwell synchronous fracturing. These fracturing technologies can produce additional stress fields that significantly influence the crack initiation pressure and the formation of an eff...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2021-01-01
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| Series: | Geofluids |
| Online Access: | http://dx.doi.org/10.1155/2021/6650710 |
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| _version_ | 1832565937920802816 |
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| author | Hongjian Wang Jin Li Fei Zhao Jinyu Dong Yanzong Cui Wanlin Gong |
| author_facet | Hongjian Wang Jin Li Fei Zhao Jinyu Dong Yanzong Cui Wanlin Gong |
| author_sort | Hongjian Wang |
| collection | DOAJ |
| description | Shale gas can be commercially produced using the stimulated reservoir volume (SRV) with multistage fracturing or multiwell synchronous fracturing. These fracturing technologies can produce additional stress fields that significantly influence the crack initiation pressure and the formation of an effective fracture network. Therefore, this study primarily investigated the evolution of crack initiation and propagation in a hydraulic rock mass under various stress conditions. Combining the in situ stress characteristics of a shale reservoir and fracturing technology, three types of true triaxial volumetric fracturing simulation experiments were designed and performed on shale, including three-dimensional constant loading, one-dimensional pressurization disturbance, and one-dimensional depressurization disturbance. The results indicate that the critical failure strength of the shale rock increases as the three-dimensional constant loads are increased. The rupture surface is always parallel to the maximum principal stress plane in both the simulated vertical and horizontal wells. Under the same in situ stress conditions in the wellbore direction, if the lateral pressure becomes larger, the critical failure strength of shale rock would increase. Additionally, when the lateral in situ stress difference coefficient is smaller, the rock specimen has an evident trend to form more complex cracks. When the shale rock was subjected to lateral disturbance loads, the critical failure strength was approximately 10 MPa less than that in the state of constant loading, indicating that the specimen with disturbance loads is more likely to be fractured. Moreover, shale rock under the depressurization disturbance load is more easily fractured compared with the pressurization disturbance. These findings could provide a theoretical basis and technical support for multistage or multiwell synchronous fracturing in shale gas production. |
| format | Article |
| id | doaj-art-8ae5067eb621490690e9a958b87493bc |
| institution | Kabale University |
| issn | 1468-8115 1468-8123 |
| language | English |
| publishDate | 2021-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geofluids |
| spelling | doaj-art-8ae5067eb621490690e9a958b87493bc2025-02-03T01:05:30ZengWileyGeofluids1468-81151468-81232021-01-01202110.1155/2021/66507106650710Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress StatesHongjian Wang0Jin Li1Fei Zhao2Jinyu Dong3Yanzong Cui4Wanlin Gong5North China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaNorth China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaNorth China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaNorth China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaNorth China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaNorth China University of Water Resources and Electric Power, Zhengzhou, 450045 Henan, ChinaShale gas can be commercially produced using the stimulated reservoir volume (SRV) with multistage fracturing or multiwell synchronous fracturing. These fracturing technologies can produce additional stress fields that significantly influence the crack initiation pressure and the formation of an effective fracture network. Therefore, this study primarily investigated the evolution of crack initiation and propagation in a hydraulic rock mass under various stress conditions. Combining the in situ stress characteristics of a shale reservoir and fracturing technology, three types of true triaxial volumetric fracturing simulation experiments were designed and performed on shale, including three-dimensional constant loading, one-dimensional pressurization disturbance, and one-dimensional depressurization disturbance. The results indicate that the critical failure strength of the shale rock increases as the three-dimensional constant loads are increased. The rupture surface is always parallel to the maximum principal stress plane in both the simulated vertical and horizontal wells. Under the same in situ stress conditions in the wellbore direction, if the lateral pressure becomes larger, the critical failure strength of shale rock would increase. Additionally, when the lateral in situ stress difference coefficient is smaller, the rock specimen has an evident trend to form more complex cracks. When the shale rock was subjected to lateral disturbance loads, the critical failure strength was approximately 10 MPa less than that in the state of constant loading, indicating that the specimen with disturbance loads is more likely to be fractured. Moreover, shale rock under the depressurization disturbance load is more easily fractured compared with the pressurization disturbance. These findings could provide a theoretical basis and technical support for multistage or multiwell synchronous fracturing in shale gas production.http://dx.doi.org/10.1155/2021/6650710 |
| spellingShingle | Hongjian Wang Jin Li Fei Zhao Jinyu Dong Yanzong Cui Wanlin Gong Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States Geofluids |
| title | Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States |
| title_full | Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States |
| title_fullStr | Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States |
| title_full_unstemmed | Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States |
| title_short | Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States |
| title_sort | experimental study of volumetric fracturing properties for shale under different stress states |
| url | http://dx.doi.org/10.1155/2021/6650710 |
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