低渗储层关井后水力裂缝二次扩展规律  

Secondary propagation of hydraulic fracture in low-permeability reservoir after shut-in

作　　者：王强 王玉丰 梁升平 赵金洲 胡永全 李勇明 WANG Qiang;WANG Yufeng;LIANG Shengping;ZHAO Jinzhou;HU Yongquan;LI Yongming(State Key Laboratory of Oil&Gas Reservoir Geology&Exploitation,Southwest Petroleum University,Chengdu 610500,Sichuan,China;No.6 Oil Production Plant,Petrochina Changqing Oilfield Company,Xi’an 710018,Shaanxi,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室,四川省成都市610500 [2]长庆油田分公司第六采油厂

出　　处：《石油钻采工艺》2023年第5期597-606,共10页Oil Drilling & Production Technology

基　　金：国家自然科学基金企业创新发展联合基金重点支持项目“深层超深层页岩气水平井压裂缝网高效建造理论与方法研究”(编号:U21B2071);国家自然科学基金联合基金项目“致密油储层压裂后关井渗吸-水化多物理场耦合作用机制研究”(编号:52174033)。

摘　　要：准确预测停泵后水力裂缝二次扩展形态对水力压裂设计具有重要意义。基于线弹性断裂力学、弹性力学、有限体积法和隐式水平集算法,建立了模拟关井时裂缝二次扩展和闭合行为的强非线性流体-应力耦合平面裂缝扩展模型。采用黏性主导Penny裂缝解析解验证了模型准确性,研究了压裂液黏度、断裂韧性和隔层应力差等对二次扩展长度的影响。结果表明:裂缝闭合与裂缝二次扩展同时发生,存在应力隔层条件时裂缝二次扩展距离更长,排量和隔层应力差与裂缝二次扩展长度呈非线性正相关;滤失系数、工程参数下断裂韧性以及压裂液黏度与裂缝二次扩展长度分别呈非线性、近线性负相关;对具有高应力差隔层、低渗以及大排量施工的储层,水力压裂设计中尤其需要考虑裂缝二次扩展长度的影响。It is significant for hydraulic fracturing design to accurately predict the secondary propagation pattern of hydraulic fracture after pump-off.Based on linear elasticing fracture mechanics,elasticing mechanics,finite volume method and Implicit Level Set Algorithm,a strongly nonlinear fluid-stress coupled planar fracture propagation model was established to simulate the secondary propagation and closure behavior of fractures after shut-in.The accuracy of the model was verified by the viscosity-dominated Penny fracture analytical solution.The effects of fracturing fluid viscosity,fracture toughness and barrier stress difference on the length of secondary propagation were studied.The results show that the fracture closure and secondary propagation coincide,and the distance of secondary propagation is much longer when there is a stress barrier.The displacement and barrier stress difference are positively correlated with the length of secondary propagation.The filtration coefficient,fracture toughness and fracturing fluid viscosity under engineering parameters have nonlinear and asymptotically linear negative correlations with the secondary propagation length of fracture,respectively.In hydraulic fracturing design,it is essential to consider the influence of secondary fracture propagation length for reservoirs with high stress difference barrier,low permeability and large displacement.

关 键 词：低渗透储层 水力压裂 关井 裂缝 二次扩展 隐式水平集算法 裂缝闭合 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]