Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method
Hydraulic fracturing (HF) technology can safely and efficiently increase the permeability of coal seam, which is conducive to CBM exploration and prevent coal and gas outburst. However, conventional HF fractures tend to expand in the direction of maximum principal stress, which may be inconsistent w...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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KeAi Communications Co., Ltd.
2023-12-01
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| Series: | Petroleum |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405656122000438 |
| _version_ | 1797387867769536512 |
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| author | Kai Wang Guodong Zhang Feng Du Yanhai Wang Liangping Yi Jianquan Zhang |
| author_facet | Kai Wang Guodong Zhang Feng Du Yanhai Wang Liangping Yi Jianquan Zhang |
| author_sort | Kai Wang |
| collection | DOAJ |
| description | Hydraulic fracturing (HF) technology can safely and efficiently increase the permeability of coal seam, which is conducive to CBM exploration and prevent coal and gas outburst. However, conventional HF fractures tend to expand in the direction of maximum principal stress, which may be inconsistent with the direction of fracturing required by the project. Therefore, the increased direction of coal seam permeability is different from that expected. To solve these problems, PFC2D software simulation is used to study directional hydraulic fracturing (DHF), that is the combination of slotting and hydraulic fracturing. The effects of different slotting angles (θ), different horizontal stress difference coefficients (K) and different injection pressures on DHF fracture propagation are analyzed. The results show that the DHF method can overcome the dominant effect of initial in-situ stress on the propagation direction of hydraulic fractures and control the propagation of fractures along and perpendicular to the slotting direction when θ, K and liquid injection pressure are small. When the DHF fracture is connected with manual slotting, the pressure will shake violently, and the fracturing curve presents a multi-peak type. The increase and decrease of particle pressure around the fracturing hole reflect the process of pressure accumulation and fracture propagation at the fracture tip respectively. Compared with conventional HF, DHF can not only shorten the fracturing time but also make the fracture network more complex, which is more conducive to gas flow. Under the action of in-situ stress, the stress between slots will increase to exceed the maximum horizontal principal stress. Moreover, with the change in fracturing time, the local stress of the model will also change. Hydraulic fractures are always expanding to the area with large local stress. The research results could provide certain help for DHF theoretical research and engineering application. |
| first_indexed | 2024-03-08T22:31:20Z |
| format | Article |
| id | doaj.art-669b84b8065342ea91ef32b4672a7fe3 |
| institution | Directory Open Access Journal |
| issn | 2405-6561 |
| language | English |
| last_indexed | 2024-03-08T22:31:20Z |
| publishDate | 2023-12-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Petroleum |
| spelling | doaj.art-669b84b8065342ea91ef32b4672a7fe32023-12-18T04:24:21ZengKeAi Communications Co., Ltd.Petroleum2405-65612023-12-0194592606Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element methodKai Wang0Guodong Zhang1Feng Du2Yanhai Wang3Liangping Yi4Jianquan Zhang5Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing, 100083, China; School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China; Corresponding author.Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing, 100083, China; School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, ChinaBeijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing, 100083, China; School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China; Corresponding author.Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing, 100083, China; School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, ChinaBeijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining and Technology (Beijing), Beijing, 100083, China; School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, ChinaHydraulic fracturing (HF) technology can safely and efficiently increase the permeability of coal seam, which is conducive to CBM exploration and prevent coal and gas outburst. However, conventional HF fractures tend to expand in the direction of maximum principal stress, which may be inconsistent with the direction of fracturing required by the project. Therefore, the increased direction of coal seam permeability is different from that expected. To solve these problems, PFC2D software simulation is used to study directional hydraulic fracturing (DHF), that is the combination of slotting and hydraulic fracturing. The effects of different slotting angles (θ), different horizontal stress difference coefficients (K) and different injection pressures on DHF fracture propagation are analyzed. The results show that the DHF method can overcome the dominant effect of initial in-situ stress on the propagation direction of hydraulic fractures and control the propagation of fractures along and perpendicular to the slotting direction when θ, K and liquid injection pressure are small. When the DHF fracture is connected with manual slotting, the pressure will shake violently, and the fracturing curve presents a multi-peak type. The increase and decrease of particle pressure around the fracturing hole reflect the process of pressure accumulation and fracture propagation at the fracture tip respectively. Compared with conventional HF, DHF can not only shorten the fracturing time but also make the fracture network more complex, which is more conducive to gas flow. Under the action of in-situ stress, the stress between slots will increase to exceed the maximum horizontal principal stress. Moreover, with the change in fracturing time, the local stress of the model will also change. Hydraulic fractures are always expanding to the area with large local stress. The research results could provide certain help for DHF theoretical research and engineering application.http://www.sciencedirect.com/science/article/pii/S2405656122000438CoalDirectional hydraulic fracturing (DHF)PFC simulationFracture propagationSlotting |
| spellingShingle | Kai Wang Guodong Zhang Feng Du Yanhai Wang Liangping Yi Jianquan Zhang Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method Petroleum Coal Directional hydraulic fracturing (DHF) PFC simulation Fracture propagation Slotting |
| title | Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| title_full | Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| title_fullStr | Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| title_full_unstemmed | Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| title_short | Simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| title_sort | simulation of directional propagation of hydraulic fractures induced by slotting based on discrete element method |
| topic | Coal Directional hydraulic fracturing (DHF) PFC simulation Fracture propagation Slotting |
| url | http://www.sciencedirect.com/science/article/pii/S2405656122000438 |
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