页岩气井多级压裂过程中地应力变化对套管载荷的影响  

Influence of In-situ Stress Variation on Casing Load During Multi-stage Fracturing of Shale Gas Well

作　　者：吴建忠[1] 张小军 李军[2,3] 张慧 连威[3] 刘鹏林 WU Jianzhong;ZHANG Xiaojun;LI Jun;ZHANG Hui;LIAN Wei;LIU Penglin(Science and Technology Management Department of Sinopec Southwest Oil&Gas Field Company,Deyang,Sichuan 618000,China;China University of Petroleum(Beijing),Beijing 102249,China;China University of Petroleum(Beijing)at Karamay,Karamay,Xinjiang 834000,China)

机构地区：[1]中国石化西南油气分公司科技管理部,四川德阳618000 [2]中国石油大学(北京),北京102249 [3]中国石油大学(北京)克拉玛依校区,新疆克拉玛依834000

出　　处：《石油管材与仪器》2022年第2期23-29,共7页Petroleum Tubular Goods & Instruments

基　　金：国家自然科学基金企业创新发展联合基金项目“海相深层高温高压钻完井工程基础理论及控制方法”(编号:U19B6003-05);国家自然科学基金联合基金重点项目“页岩气水平井井筒完整性失效机理与控制方法”(编号:U1762211);中国石油化工股份有限公司西南油气分公司横向委托课题“威荣深层页岩气井套管变形预防与控制关键技术研究”(编号:34450000-20-ZC0607-0006)。

摘　　要：近年来,页岩气水平井多级压裂过程中的套管变形问题日渐突出,导致后续压裂施工发生大量丢段、弃段,严重影响了页岩气井产量。考虑到页岩气井变形点普遍分布在套管跟端位置,因此认为多级压裂过程中的应力累积可能是导致套管变形的主要原因,针对该观点对多级压裂过程中的近井筒地应力变化规律及其对套管载荷的影响展开研究。首先,统计分析了威荣区块套管变形形状特征和分布特征;然后以威荣M井为例,建立多级压裂数值模型,计算近井地应力随压裂级数的变化规律;在此基础上,以最后一级压裂段作为研究对象,建立套管-水泥环-地层组合体模型,研究不同地应力条件下套管载荷的大小。研究结果表明:在多级水力裂缝起裂和扩展过程中,多级压裂产生的诱导应力会对后续压裂段产生影响,导致近井筒地应力发生非均匀累积;随着多级压裂过程中地应力累积的影响,研究点处的套管等效应力逐渐增加。该研究成果可为多级压裂过程中套管完整性控制提供参考。In recent years,casing deformation in the multi-stage fracturing process of horizontal shale gas wells has become increasingly prominent,leading to a large number of stage loss and abandonment in subsequent fracturing construction,which seriously affects the production of shale gas wells.Considering that the deformation points of shale gas wells are generally distributed at the heel of casing,it is considered that stress accumulation in the process of multi-stage fracturing may be the main cause of casing deformation.Based on this point of view,this paper studies the variation law of in-situ stress near the wellbore in the process of multi-stage fracturing and its influence on casing load.Firstly,the characteristics of casing deformation shape and distribution in Weirong block are analyzed statistically.Then,taking Weirong M well as an example,a multi-stage fracturing numerical model was established to calculate the variation of in-situ stress near the well with fracturing stages.On this basis,taking the last stage of fracturing as the research object,the casing-cement-formation combination model was established to study the size of casing load under different in-situ stress conditions.The results show that in the process of multi-stage hydraulic fracture initiation and propagation,the induced stress generated by multi-stage fracturing will have an impact on the subsequent fracture stages,leading to non-uniform accumulation of in-situ stress near the wellbore.With the influence of in-situ stress accumulation during multi-stage fracturing,the equivalent stress of casing at the research site increases gradually.The research results can provide some reference for casing integrity control during multi-stage fracturing.

关 键 词：威荣区块 页岩气 多级压裂 地应力变化 套管变形 

分 类 号：TE931.2[石油与天然气工程—石油机械设备]