INVERSION OF UPPER CRUSTAL STRESS STATE WITH COLLAPSE DATA FROM INCLINED BOREHOLES BY GENETIC ALGORITHMS

It is a non linear inversion to calculate crustal stress field with collapse data of inclined borehole.Genetic algorithm is one of the most effective methods to solve the inverse problem.In this paper,according to collapse model we tested the effectiveness of genetic algorithm with analog data.We processed the collapse data from 6 inclined oil wells in Raoyang sag and Shenxian sag in the middle part of Hebei province,and reversed the crustal stress state of the two sags with genetic algorithm.Compared with the join method of non linear inversion and enumeration,the amount of calculation is greatly reduced and the results are satisfactory.