Analysis of expansion direction and pore pressure change law of hydraulic cracks through plane

In the hydraulic fracturing project of the hard roof plate, in order to make the hydraulic crack more easily pass through the rock layer and increase the extension range of the hydraulic crack in the roof plate, the influencing factors of the expansion direction of the hydraulic crack through the plane are analyzed through theoretical calculation, and the ABAQUS numerical simulation software is used to establish a two-dimensional model of the crack expansion based on the Cohesive unit when the hydraulic crack passes through the level, and analyzes the expansion direction and the pressure change law of the hydraulic crack at the level under different stress conditions and angles with the plane.Combined with the pore pressure monitoring data of fracturing at different drilling angles of the 1109 working face of Yidong Coal Mine, the simulation results are verified.The results show that the hydraulic crack crossing the plane is generally related to the stress, approximation angle and stratum friction factor perpendicular to the plane.The greater the stress perpendicular to the level, the easier it is for hydraulic cracks to pass through the stratigraphic level; under other conditions, the hydraulic crack approximation angle α has a quadratic relationship with the minimum vertical stress S_y required to cross the plane, and when the approximation angle is about 70°, the hydraulic crack is most likely to directly pass through the natural crack; if the hydraulic crack is turned along the natural crack, there will be a significant secondary decline in the hydraulic pressure.