Numerous cases of casing failure have been reported worldwide. Depletion-induced compaction is one of the main factors that may cause casing failure. Stress perturbation in salt layers may accommodate rock flow which endangers the stability of cased wells. Besides, poor cementing jobs are recognized as one of the wellbore instability causes. These factors need to be considered to determine the mechanism behind the casing failure. In this study, the creep behavior of the caprock salt layer in the southwest Iranian oil fields is experimentally studied through a number of creep tests under conditions of elevated temperature and pressure. Then, a three-dimensional finite element analysis is utilized to examine the validity of various casing failure scenarios after calibrating the model with well logs and experimental data. The results confirmed that the combined effects of creep behavior of rock salt and cementing imperfection can be the main cause of failure in the wellbore under study, because the failure time and depth predicted by the numerical simulation were found to be in accordance with the real field data. By history matching, the geomechanical parameter of the salt layer has been modified for study of the casing failure in other wells in the same formation.

中文翻译：

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盐岩套管失效原因的数值研究

世界范围内已经报道了许多套管故障的案例。衰竭引起的压实是导致套管失效的主要因素之一。盐层中的应力扰动可能会适应危及套管井稳定性的岩流。此外，固井作业不佳被认为是井眼不稳定的原因之一。需要考虑这些因素来确定套管失效背后的机制。本研究通过多次高温高压条件下的蠕变试验，对伊朗西南部油田盖层盐层蠕变行为进行了实验研究。然后，在使用测井记录和实验数据校准模型后，利用三维有限元分析来检查各种套管故障场景的有效性。结果证实，岩盐蠕变行为和固井缺陷的共同影响可能是所研究井筒失效的主要原因，因为数值模拟预测的失效时间和深度与实际现场一致。数据。通过历史匹配，修改盐层地质力学参数，用于研究同一地层其他井的套管失效。