基于套变数据的盐岩地层非均匀地应力反演

非均匀地应力是直接造成套管承受非均匀载荷和间接造成套管挤毁损坏的主要原因之一,而套管变形数据与地应力变化密切相关。基于套管变形数据,利用最小二乘法建立非均匀地应力优化反演模型。将套管内壁观测点实际变形量与计算变形量差值的平方作为目标优化函数,非均匀地应力作为设计变量,采用零阶函数最小二乘逼进优化方法,对满足套管内径变形量条件下的非均匀地应力进行有限元数值优化反演分析。并基于全井段测井资料的岩石力学参数解释,对川东北某气田HY1井不同套损段的非均匀地应力进行反演计算。计算结果为该区块后续钻井设计、套管强度设计及修井作业等提供依据,该方法为盐岩地层非均匀地应力的获取提供了新途径。

Inversion study on non-uniform in-situ stress in salt formation based on casing deformation data

The non-uniform in-situ stress is one of the main reasons that directly cause casing to bear non-uniform loads and indirectly cause casing collapse damage,and the casing deformation data is closely related to the change of in-situ stress.Based on the casing deformation data,the optimal inversion model of non-uniform in-situ stress is established by the least square method.Using the above optimal inversion model,the square of the difference between the actual deformation and the calculated deformation of the casing inner wall is taken as the objective optimization function,and the non-uniform in-situ stress is taken as the design variable.The optimal inversion analysis of the non-uniform in-situ stress satisfying the casing inner diameter deformation is carried out by the least square approximation optimization method of zero-order function.Based on the interpretation of rock mechanics parameters from well logging data,the inversion calculations of non-uniform in-situ stress in different casing damage formation sections of a gas field HY1 in northeastern Sichuan are conducted.The calculation results provide a basis for subsequent drilling design,casing strength design and workover operation in the area.The method provides a new way for obtaining non-uniform in-situ stress in salt formation.