Field experience shows that horizontal well multi-stage fracturing technology can transform the volumetric pressure crack network in the formation and has been widely used in unconventional oil and gas resource exploitation. According to the requirements of horizontal well fracturing operations, this paper simulates the law of horizontal well fracturing in low-porosity and low-permeability sand-shale formation by large-mold fracturing tests and analyzes crack initiation and extension. The two completion methods of open-hole completion and casing perforation completion are considered, and the maximum and minimum horizontal principal stress difference is 10 and 4 MPa. The horizontal wellbore azimuth angle changes from 0° to 90°. The test results show that the principal stress difference has a great influence on fracture initiation. The smaller the stress difference, the higher the fracture initiation pressure and the more complicated the fracture initiation and extension. The fracture propagates along the axial direction of the wellbore, and then at both ends of the wellbore the fracture turns to the direction perpendicular to the direction of the minimum horizontal principal stress. The horizontal wellbore can form a transverse fracture by drilling along the direction of the minimum horizontal principal stress. This study is of great significance for understanding the fracture initiation and propagation law of horizontal well fracturing and can provide guidance for multi-stage fracturing operations of horizontal wells in unconventional reservoirs.

中文翻译：

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水平井裂缝扩展特征

现场经验表明，水平井多级压裂技术可以改造地层体积压力裂缝网络，在非常规油气资源开发中得到广泛应用。根据水平井压裂作业的要求，通过大模压裂试验模拟低孔低渗砂页岩地层水平井压裂规律，分析裂缝的萌生和延伸规律。考虑裸眼完井和套管射孔完井两种完井方式，最大和最小水平主应力差分别为10和4 MPa。水平井筒方位角从0°变化到90°。试验结果表明，主应力差对断裂起裂影响较大。应力差越小，起裂压力越高，起裂和延伸越复杂。裂缝沿井筒轴向扩展，然后在井筒两端裂缝转向垂直于最小水平主应力方向的方向。水平井筒沿最小水平主应力方向钻进可形成横向裂缝。该研究对于了解水平井压裂裂缝起裂及扩展规律具有重要意义，可为非常规油藏水平井多级压裂作业提供指导。裂缝沿井筒轴向扩展，然后在井筒两端裂缝转向垂直于最小水平主应力方向的方向。水平井筒沿最小水平主应力方向钻进可形成横向裂缝。该研究对于了解水平井压裂裂缝起裂及扩展规律具有重要意义，可为非常规油藏水平井多级压裂作业提供指导。裂缝沿井筒轴向扩展，然后在井筒两端裂缝转向垂直于最小水平主应力方向的方向。水平井筒沿最小水平主应力方向钻进可形成横向裂缝。该研究对于了解水平井压裂裂缝起裂及扩展规律具有重要意义，可为非常规油藏水平井多级压裂作业提供指导。水平井筒沿最小水平主应力方向钻进可形成横向裂缝。该研究对于了解水平井压裂裂缝起裂及扩展规律具有重要意义，可为非常规油藏水平井多级压裂作业提供指导。水平井筒沿最小水平主应力方向钻进可形成横向裂缝。该研究对于了解水平井压裂裂缝起裂及扩展规律具有重要意义，可为非常规油藏水平井多级压裂作业提供指导。