Archive | 2021
Study on in-Situ Stress Distribution in the East and West of Sichuan Basin
Abstract
\n This paper statistically analyzed 112 acoustic emission experimental data of cores from 38 wells in the Upper Permian Changxing Formation, Triassic Xujiahe Formation, Leikoupo Formation, Jialingjiang Formation, and Feixianguan Formation in the northeastern Sichuan Basin, and 106 acoustic emission test data of cores from 32 wells of the Jurassic Shaximiao Formation and Penglai Formation in western Sichuan, eliminated data with large errors, established scatter plots of in-situ stress changing with depth in northeastern and western Sichuan, and carried out corresponding regression analysis. Studies show that the in-situ stress distribution rules in northeastern Sichuan and western Sichuan are quite different, which are mainly related to the evolution and tectonic movement of basin. The vertical stress of two blocks is generally linear with the depth, and the vertical stress value is related to the rock. The difference between overburden weight and vertical stress is small. The maximum and minimum horizontal principal stresses gradually increase with buried depth, and the degree that horizontal principal stress increase with buried depth in northeastern Sichuan is generally greater than that in western Sichuan. The horizontal shear stress is also linear with buried depth. The corresponding linear relationship is stronger in the western part of Sichuan, while the dispersion in the eastern part of Sichuan has an increasing trend as the buried depth increases. The elastic modulus of rock directly affects stress value of rock. Generally, the higher the elastic modulus of rock, the better it is to maintain higher stress. The elastic modulus of rocks of different genesis is obviously different, and the relationship between the stress value of rock and the elastic modulus is quite different. Because strength of carbonate rock is greater than that of sandstone, the change of elastic modulus is the maximum level of carbonate rock. The influence of principal stress is greater than that of sandstone, and the influence of minimum principal stress of sandstone is greater than that of carbonate rock. In carbonate rock, the effect of elastic modulus on the minimum horizontal principal stress is greater than the maximum horizontal principal stress, while in sandstone it is the opposite.