Analysis of mechanical strengths of extreme line casing joint considering geometric,material,and contact nonlinearities

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外文摘要：To address the challenges associated with difficult casing running,limited annular space,and poor cementing quality in the completion of ultra-deep wells,the extreme line casing offers an effective solution over conventional casings.However,due to its smaller size,the joint strength of extreme line casing is reduced,which may cause failure when running in the hole.To address this issue,this study focuses on the CST-Zr Φ139.7 mm × 7.72 mm extreme line casing and employs the elastic-plastic me-chanics to establish a comprehensive analysis of the casing joint,taking into account the influence of geometric and material nonlinearities.A finite element model is developed to analyze the forces and deformations of the extreme line casing joint under axial tension and external collapse load.The model investigates the stress distribution of each thread tooth subjected to various tensile forces and external pressures.Additionally,the tensile strength and crushing strength of the extreme line casing joint are determined through both analytical and experimental approaches.The findings reveal that,under axial tensile load,the bearing surface of each thread tooth experiences uneven stress,with relatively high equivalent stress at the root of each thread tooth.The end thread teeth are valuable spots for failure.It is observed that the critical fracture axial load of thread decreases linearly with the increase of thread tooth sequence.Under external pressure,the circumferential stress is highest at the small end of the external thread,leading to yield deformation.The tensile strength of the joint obtained from the finite element model exhibits a relative error of less than 7％compared to the analytical and experimental values,proving the reliability of the finite element model.The tensile strength of the joint is 3091.9 kN.Moreover,in terms of anti-collapse capability,the joints demonstrate higher resistance to collapse compared to the casing body,which is consistent with the test results where the pipe body experiences collapse and failure while the joints remain intact during the experiment.The failure load of the casing body under external collapse pressure is 87.4 MPa.The present study provides a basic understanding of the mechanical strengths of extreme line casing joint.

外文关键词：

Extreme line casingElastic-plastic mechanicsFinite element analysisTensile strengthCollapse strength

作者：

Ji-Yun Zhang、Chi Peng、Jian-Hong Fu、Quan Cao、Yu Su、Jian-Yun Pang、Zi-Qiang Yu

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作者单位：

Petroleum Engineering School,Southwest Petroleum University,Chengdu 610500,Sichuan,China

Engineering Technology Research Institute of CNPC Southwest Oil and Gas Field Company,Chengdu,610017,Sichuan,China

基金：

National Natural Science foundation of ChinaScience and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance

项目编号：

521040062020CX040202

出版年：

2024

DOI：

10.1016/j.petsci.2024.02.014

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(3)