Methods Of Determining The In-situ Stress Distribution For Heterogeneous Reservoirs

In the exploration of oil and gas resources,it is of vital importance for engineers to obtain the exact values of the in-situ stresses and their distribution.This thesis hopes to study the tests of determining the in-situ stresses and their distribution for a more exact result which can guide the real engineering practice.Comparison analyses are used to study the tests and the in-situ distribution for heterogeneous reservoirs,the former is designed to study two influential factors,including time effect and the loading rate,and the latter is conducted with FEM and least square method to simulate the in-situ distribution for heterogeneous reservoirs,considering the material properties which follow the random distribution in different ranges.Test results of DSCA show that time effect could affect the accuracy of DSCA results and as the time becomes longer,the difference becomes larger.However,the influence of the loading rate can be neglected.According to the simulating results,the models with heterogeneous parameters have large effect on the calculating results,and affected by the different random ranges,the in-situ stresses have bigger ranges when the random distributions are setting with bigger ranges.It means that the homogeneous material properties lead to narrow ranges compared with the heterogeneous ones,and in practice,it is less similar with the real in-situ stress distribution than the heterogeneous,which means the real distribution has a wider stress range.The thesis also conducts simulations based on three drilling areas in an oil field and the results are both showed in two and three dimensions.