有限元法在油气井井壁稳定计算中的应用

APPLICATION OF THE FINITE ELEMENT METHOD IN CALCULATING SIDEWELL STABILITY

油气井井壁稳定问题是近年钻井工程研究的热门课题，通过大量文献调研表明，世界范围内每年用于处理油气井井壁失稳的费用高达5亿美元，损失钻井时间5％～6％。有限元分析方法能够解决井壁岩石在复杂受力条件下的最大应力集中带，采用摩尔一库仑强度准则验证岩体失稳强度。根据地应力的3个主应力，建立井眼稳定的三维模型，利用有限单元法划分单元网格，通过计算得到了井壁处的最大应力，为解决油气井井壁稳定问题提供了重要的理论依据。

Nowadays the problem of the oil and gas well sidewall stability is becoming more and more popular in drilling engineering. Through the investigation of a large number of literatures about hole stability researches, it shows that the paid for doing with the oil and gas well sidewall of losing stability reach 0.5 billion in one year all over the world, the drilling time is delayed 5% - 6% . According to the finiteelement method, calculated the maximum stress concentration zone of sidewall rock under complicated stress conditions, adopting the Mohr-coulomb criteria verified the rock breakdown stress. Based on the three stratigraphic main stresses, the 3-D model of sidewall stability was set up. Make use of the finite element method divide the unit meshing, through the calculation, the maximum stress around sidewall is got. It should provide the important theoretical basis for solving the oil and gas well sidewall stability.