断层附近非均匀应力场页岩压裂缝网扩展模拟

Shale fracture network propagation simulation in non?鄄uniform stress field near fault

陈珂 于志豪 王守毅 任岚 宋雯静 林然

四川页岩气勘探开发有限责任公司，四川 内江 641100 西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500 中国石油西南油气田分公司页岩气研究院，四川 成都 610051

Sichuan Shale Gas Exploration and Development Co., Ltd, Neijiang 641100, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China Research Institute of Shale Gas, Southwest Oil and Gas Field Company, PetroChina, Chengdu 610051, China

压裂过程中水力裂缝的延伸行为对页岩气增产改造效果至关重要。然而部分页岩地层断层较发育，附近地应力场呈现非均匀分布，最大水平主应力方向随空间位置发生变化，若水平井井筒仍沿垂直于原始最大水平主应力方向部署，水力裂缝可能出现非平面偏转延伸行为，进而影响缝网体积。文中为揭示页岩地层断层发育对水力裂缝延伸及缝网体积的影响，建立了断层附近非均匀应力场计算模型，并在此基础上构建了断层影响下的页岩气水平井分簇裂缝偏转延伸模型和缝网体积计算模型，模拟并分析了非均匀应力场下的水力裂缝延伸及压裂缝网扩展规律。结果表明：平移断层附近水力裂缝趋向平行于断层方向延伸，而正断层附近水力裂缝趋向垂直于断层方向延伸。页岩气水平井井筒垂直于最大水平主应力方向部署后，可以减小射孔孔眼摩阻，减少施工压力损失，提高缝内净压力，增大缝网体积。该研究可为页岩地层内断层附近的水平井井眼轨迹部署提供重要的理论依据。

 The propagation behavior of hydraulic fractures during the fracturing process is critical to the effect of shale gas reservoir stimulation. However, a part of shale formations have developed faults and there is a non-uniform distribution in the nearby in-situ stress field. Also, the maximum horizontal main stress direction varies with the spatial position. If the horizontal wellbore is still deployed along the original maximum horizontal main stress direction, non-planar deflection propagation behavior in hydraulic fractures is possible to affect stimulated reservoir volume then. The purpose of this paper is to reveal the effect of the development of faults in the shale formation on the propagation of hydraulic fractures and stimulated reservoir volume. A calculation model for the non-uniform in-situ stress field near the fault is established, and segmented multi-cluster fracturing deflection propagation model and stimulated reservoir volume calculation model in horizontal shale gas well under the influence of faults are constructed on this basis. Furthermore, the fracture extension and propagation law was simulated and analyzed in the presence of a non-uniform in-situ stress field. The results show that hydraulic fractures near the strike-slip fault tend to run parallel to the fault direction, whereas hydraulic fractures near the normal fault tend to run perpendicular to the fault direction. After making the horizontal shale gas wellbore perpendicular to the maximum horizontal main stress direction, the perforation friction and fracturing pressure loss can be reduced, the net pressure in the fracture is increased and stimulated reservoir volume is stimulated. The research result could provide an important theoretical foundation for the design of borehole trajectory of horizontal wells near faults in shale formations.

10.6056/dkyqt202302005