四川盆地昭通页岩气水平井水力压裂套管外载分析  

External Load Analysis of Hydraulic Fracturing Casing in Zhaotong Shale Gas Horizontal Well of Sichuan Basin

作　　者：孟胡 申颍浩[1] 朱万雨[2] 李小军[2] 雷德荣[2] 葛洪魁[1] Meng Hu;Shen Yinghao;Zhu Wanyu;Li Xiaojun;Lei Derong;Ge Hongkui(Unconventional Petroleum Research Institute,China University of Petroleum(Beijing),Beijing 102249,China;PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China)

机构地区：[1]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [2]中国石油新疆油田分公司,新疆克拉玛依834000

出　　处：《特种油气藏》2023年第5期166-174,共9页Special Oil & Gas Reservoirs

基　　金：国家重点研发计划“川南国家级页岩气示范区地震活动性风险评估与对策研究”(2020YFA0710600)。

摘　　要：针对昭通页岩气示范区水力压裂过程中的套管损坏问题,基于套管变形特征及理论分析,建立了套管-水泥环-地层组合体数值模型,研究温度效应、裂缝网络诱导应力、微裂隙、地层滑移及固井质量等因素增大套管外载的作用机制。研究表明:水力压裂导致压裂改造区域地应力场非均匀变化,并在水平井跟端及中部区域大幅增加地应力场及最大水平地应力与垂向地应力差;裂缝网络诱导应力、温度效应、微裂隙、地层滑移及固井质量缺陷均会增大套管外载,其中,水力压裂产生的诱导应力增加套管外载的作用最为显著,这可能是水平井跟端及中部区域套管损坏概率高的主要原因;由于高施工压力及高应力差,昭通区域层理、天然裂缝等弱面在水力压裂过程中易发生剪切滑移,当弱面与井筒夹角为45°时,套管变形量及受力最大。该研究结果可为页岩气田水平井套管强度设计及套管变形预防提供指导。In view of casing damage during hydraulic fracturing in Zhaotong shale gas demonstration area,a numerical model of casing-cement sheath-formation combination was established based on casing deformation characteristics and theoretical analysis to study the mechanism of increasing casing external load by temperature effect,fracture network-induced stress,microfracture,formation slip and cementing quality.The study shows that the hydraulic fracturing leads to non-uniform change of the stress field in the Earths crust in the fracture reconstruction area,and greatly increases the stress field in the Earths crust and the difference between the maximum horizontal and vertical crustal stress in the heel and middle areas of horizontal wells;the induced stresses of fracture network,temperature effect,microfracture,formation slip and cementing quality defects will increase the external load of casing,among which the induced stresses generated by hydraulic fracturing has the most significant effect on increasing the external load of the casing,which may be the main reason for the high probability of damage to the casing in the heel and middle areas of horizontal wells.This may be the main reason for the high probability of casing damage at the heel end and central area of horizontal wells.Due to the high construction pressure and high stress difference,the weak surfaces such as stratigraphy and natural fractures in Zhaotong area are prone to shear slip in the process of hydraulic fracturing,and the casing deformation and force are the largest when the angle of the weak surface and the wellbore is 45°.The study results provide guidance for casing strength design and casing deformation prevention in horizontal wells of shale gas fields.

关 键 词：页岩气 水力压裂 套管外载 套管损坏 应力场 昭通页岩气示范区 

分 类 号：TE243[石油与天然气工程—油气井工程]