Theoretical and experimental analyses of casing collapsing strength under non-uniform loading  

作　　者：林元华 邓宽海 曾德智 朱红钧 朱达江 戚兴 黄韵 

机构地区：[1]State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University) [2]School of Materials Science and Engineering, Southwest Petroleum University [3]National Petroleum Corporation Key Lab for Tubular Goods Engineering (Southwest Petroleum University)

出　　处：《Journal of Central South University》2014年第9期3470-3478,共9页中南大学学报（英文版）

基　　金：Projects(51074135,51274170,51004084)supported by the National Natural Science Foundation of China

摘　　要：Failure data from oilfield showed that casings which were designed according to API standards were deformed and collapsed in salt formations. The main reason for decrease in strength may be caused by non-uniform loading(NUL) that was not considered in traditional casing collapsing strength design or that the designing method should be improved and developed. Obviously, the calculation of casing collapse strength is one of the key factors in casing design. However, the effect of NUL on casing collapse strength was generally neglected in the present computational methods. Therefore, a mechanical model which can calculate casing collapse strength under NUL was established based on the curved beam theory of the elasticity and was solved using displacement method. Simultaneously, three anti-collapse experiments were performed on C110 casing under NUL, and the strain and deformation laws of three casings in the process of collapse were obtained by the electrical method. Yield limit of every casing was obtained by analyzing those data. Experimental results are consistent with the results of calculation of new model. It indicates that the model can be used to calculate yield limit loading of casings under NUL.Failure data from oilfield showed that casings which were designed according to API standards were deformed and collapsed in salt formations. The main reason for decrease in strength may be caused by non-uniform loading（NUL） that was not considered in traditional casing collapsing strength design or that the designing method should be improved and developed. Obviously, the calculation of casing collapse strength is one of the key factors in casing design. However, the effect of NUL on casing collapse strength was generally neglected in the present computational methods. Therefore, a mechanical model which can calculate casing collapse strength under NUL was established based on the curved beam theory of the elasticity and was solved using displacement method. Simultaneously, three anti-collapse experiments were performed on C110 casing under NUL, and the strain and deformation laws of three casings in the process of collapse were obtained by the electrical method. Yield limit of every casing was obtained by analyzing those data. Experimental results are consistent with the results of calculation of new model. It indicates that the model can be used to calculate yield limit loading of casings under NUL.

关 键 词：non-uniform loading mechanical model collapse testing collapse strength 

分 类 号：TE31[石油与天然气工程—油气田开发工程]