Failure evaluation mechanism of cement sheath sealing integrity under casing eccentricity during multistage fracturing

扫码查看

原文链接

NETL
NSTL
万方数据

外文摘要：A microannulus(MA)is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells.However,the effect of the casing eccentricity on the long horizontal section has not been considered.In this study,a full-scale integrity tester for cement sheaths is adopted to measure the cu-mulative plastic deformation.Numerical models are applied to evaluate the development of the cu-mulative plastic deformation and quantify the MA width considering casing centralization and eccentricity in the context of multiple loading and unloading cycles.Subsequently,the influences of the eccentricity distance and angle,cement-sheath mechanical variables,and different well depths on the cumulative sheath plastic deformation and sheath MA development are explored.The research results demonstrate that casing eccentricity significantly increases the cumulative sheath plastic deformation compared with that of the casing-centered condition.Consequently,the risk of sealing integrity failure increases.The accumulated plastic deformation increases when the eccentricity distance increases.In contrast,the initial plastic deformation increases as the eccentricity angle increases.However,the cu-mulative plastic deformation decreases after a specific loading and unloading cycle count.Affected by the coupled influence of the internal casing pressure and fracturing stages,the width of the MA in the horizontal section increased from the toe to the heel,and the casing eccentricity significantly increased the MA width at each stage,thus increasing the risk of gas channeling.Finally,an engineering case is considered to study the influence of casing eccentricity.The results show that cement slurries that form low and high elastic moduli can be applied to form a cement sheath when the fracturing stage is lower or higher than a specific value,respectively.The results of this study offer theoretical references and en-gineering support for the integrity control of cement sheath sealing.

外文关键词：

Cement sheathMicroannulusCasing eccentricityNumerical simulation

作者：

Yan Xi、Yu Yao、Xue-Li Guo、Jun Li、Yu-Dong Tian、Gong-Hui Liu

展开 >

作者单位：

Beijing University of Technology,Beijing,100124,China

Beijing University of Technology,Beijing 100124,China

CNPC Engineering Technology R&D Company Ltd.,Beijing,102200,China

China University of Petroleum-Beijing at Karamay,Karamay,834000,Xinjiang,China

China University of Petroleum-Beijing,Beijing,102249,China

CNPC Daqing Drilling Engineering Corporation,Daqing,163311,Heilongjiang,China

展开 >

出版年：

2024

DOI：

10.1016/j.petsci.2024.04.013

石油科学(英文版)

中国石油大学（北京）

石油科学(英文版)

影响因子：0.88

ISSN：1672-5107

年,卷(期)：2024.21(5)