煤储层裸眼水平分支水力裂缝起裂特征分析

Hydraulic fracture initiation characteristics of horizontal branches with open hole in coal reservoirs

刘秉谦¹ 张遂安¹ 张羽¹ 贺甲元² 郑磊¹ 肖凤朝³

中国石油大学（北京）石油工程学院，北京 102249 中国石化石油勘探开发研究院，北京 100083 中国矿业大学（北京）地球科学与测绘工程学院，北京100083

College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China Exploration and Production Research Institute, SINOPEC, Beijing 100083, China College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China

基于三维弹性力学和岩石断裂力学理论，提出考虑原地应力、井眼内压引起的应力和压裂液滤失引起的应力的情况下，结合径向井裸眼水平分支井壁应力分布模型，建立岩石本体张性起裂、沿天然裂缝剪切起裂和沿天然裂缝张性起裂3种起裂模式下的起裂压力计算模型，综合预测分析煤储层中水力裂缝受发育天然裂缝干扰影响下的起裂特征。研究结果表明，水力裂缝起裂特征受水平分支方位、应力状态和天然裂缝共同作用影响，当径向井裸眼水平分支与天然裂缝相交时，水力裂缝易沿天然裂缝张性起裂。

Based on the theory of three dimensional elastic mechanics and rock fracture mechanics, considering the situation of stress distribution around the open horizontal branch wellbore of radial horizontal well caused by in-situ stress, wellbore pressure and filtration of fracture fluid, calculation models of initiation pressure for three initiation patterns, tensional fracture initiating from rock body, shear fracture along natural fractures and tensional fracture along natural fractures, were established to predict and analyze the characteristics of fracture initiation in coal bed. The results show that the orientation of horizontal branch, stress state and natural fractures work together to influence the characteristics of fracture initiation, and hydraulic fractures tend to initiate with tensional fracture along the natural fractures if horizontal branches with open hole of radial horizontal well intersect natural fractures.

10.6056/dkyqt201602022