断块油气藏开采对地应力和破裂压力的影响规律  

Influences of Oil and Gas Production on In-Situ Stress and Fracture Pressure in Fault-Block Reservoirs

作　　者：赵凯[1] 赵文龙 石林 李波[3] 高辉[1] 刘顺[1] ZHAO Kai;ZHAO Wenlong;SHI Lin;LI Bo;GAO Hui;LIU Shun(College of Petroleum Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China;Greatwall Drilling Company, CNPC,Panjing, Liaoning 124010, China;No.1 Gas Production Plant, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China)

机构地区：[1]西安石油大学石油工程学院,西安710065 [2]中国石油集团长城钻探工程有限公司,辽宁盘锦124010 [3]中国石油新疆油田分公司采气一厂,新疆克拉玛依834000

出　　处：《新疆石油地质》2017年第6期723-728,共6页Xinjiang Petroleum Geology

基　　金：国家自然科学基金(51604225);中国石油科技创新基金项目(2016D-5007-0207)

摘　　要：地应力和破裂压力是油藏实施压裂增产措施中所必需的基础参数,断块油气藏长期开采后,地应力和破裂压力会发生较大变化。根据多孔介质弹性力学理论,分析了断块油气藏储集层压力衰竭对地应力大小和方向的影响,在此基础上,研究了压裂起裂和延伸的变化规律。结果表明,断块油气藏储集层压力衰竭导致地应力非均匀衰减,压裂过程中裂缝延伸压力线性降低,裂缝延伸方向发生偏转,且在压力衰竭初期偏转快,后期偏转慢;储集层压力衰竭导致裸眼井起裂压力线性降低,断块油气藏开采后破裂压力的降低幅度较传统无限大均质油藏更大,且定向井压裂施工的难易程度与井眼轨迹的关系发生了变化,对于断块油气藏而言,若在开发后期进行压裂增产作业,可根据压力衰竭程度合理设计井眼轨迹,降低压裂作业的施工难度。As the basic parameters needed in reservoir fracturing stimulation,in-situ stress and fracture pressure will change significantly after a long period of production in fault-block reservoirs.According to the elastic mechanics theory for porous media,the paper analyzes the influences of fault-block reservoir pressure depletion on in-situ stress size and direction,based on which the variations of crack initiation and extension are studied.The results show that fault-block reservoir pressure depletion results in inhomogeneous attenuation of in-situ stress,fracture extension pressure declines linearly during fracturing,fracture extension direction deflects rapidly at the early stage of pressure depletion and relatively slowly at the late stage of pressure depletion;reservoir pressure depletion leads to the linear decline of crack initiation pressure in an open hole.The fracture pressure reduction extent in fault-block reservoirs is larger than that in conventional homogeneous reservoirs after the reservoirs are put into production,and the relationship between fracturing feasibility degree and wellbore trajectory in directional wells changes.For fault-block reservoirs,wellbore trajectory should be designed reasonably according to pressure depletion extent to reduce the difficulties of fracturing operation if fracturing stimulation is needed at the late production stage.

关 键 词：断块油气藏 压裂开采 压力衰竭 地应力 破裂压力 

分 类 号：TE21[石油与天然气工程—油气井工程]