Numerical simulation of the influence of stimulated reservoir volume on in-situ stress field

In recent years, the stimulated reservoir volume is a new developing technology applied to the effective exploitation of low permeability shale gas reservoirs. Despite of its superiority and potential, the geostress field is under a complex mechanical environment during the volume fracturing process due to excessive stimulated stages, large fracturing volume, high injection capacity, and increasing dense areas of microseismic events. Based on the drilling and completion data and microseismic monitoring data of Sichuan shale gas horizontal well X201-H1, the three-dimensional finite element model of volume fracturing is established, combining fluid-solid interaction mechanics with the basic theory of rock damage mechanics. According to the established model, the finite element analysis on different fracturing conditions is carried out, which finally results in the stress distribution of near-wellbore area after each staged fracturing operation. The results show that: 1) The change of pore pressure caused by volume fracturing can generate induced stress field, which leads to the re-orientation of in-situ stress field and even the appearance of tension stress areas and zero stress areas within the region of volume fracturing stimulation. 2) The existence of stress field interference in different stages of fracturing operations leads to the change in the magnitude and direction of stress field after each staged fracturing. Research methods and results of the paper will provide guiding significance to the optimization design of staged fracturing of horizontal wells to some extent.