Numerical simulation study on the mechanical behavior of shale core and reservoir rock mass

Abstract

AbstractAfter the hydraulic fracturing of the shale reservoir, the stress field changes during the mining process. The stress sensitivity of the reservoir affects its development capabilities. Moreover, the stress sensitivity of shale reservoirs obtained by various researchers using different experimental methods is not uniform. This study analyzes the physical background differences between reservoir rock mass and experimental core. In this study, we establish the “support structure model” of the reservoir and show that the reservoir rock body has a structural overall effect, such that the supporting effect of the surrounding rock on the overlying strata is very strong. At the same time, we also establish the transverse isotropic numerical model of the shale reservoir on the basis of the real physical background of the reservoir and the experimental physical core model on the basis of the real physical background of the core test. This study shows that the equivalent mechanical behavior of the core test in the holder is pure core compression without the support and pull of the whole rock mass structure. In the real reservoir, the reservoir rock mass has significant structural effect. The actual compression change of real reservoir mining is less than the pure compression displacement of the experimental test core. The core stress sensitivity of the conventional experimental test does not directly describe the true stress‐strain effect of the macroscopic reservoir rock mass as a structural whole. A laboratory stress‐sensitive test apparatus and method that is equivalent to the physical background of a real reservoir needs to be improved or designed.