Numerical simulation of the pore-fracture propagation law of single-hole shale during hydraulic fracturing with fluid–solid coupling

To explore the rule of pore-fracture propagation in the course of hydraulic fracturing of a single pore shale under the action of fluid–structure coupling, a numerical model was established for 8 groups of single pore shales present in the Niutitang Formation of the northern Guizhou area. Different bedding dip angles and different hydraulic pressures were used with the numerical software RFPA 2D -Flow. The results showed that: 1) the elastic modulus and compressive strength of shale showed pronounced anisotropy due to the influence of different water pressures and bedding dip angles; 2) for the same water pressure, the curve for compressive strength was V -shaped as the bedding dip angle rose; 3) with the same bedding dip angle, the compressive strength of single pore rock samples was negatively correlated with the increase in hydraulic compressive strength; 4) based on the distribution of cracks in samples with different bedding inclination angles and hydraulic pressures, the samples were divided according to three final failure modes, namely inclined type I (0°/30°/60° 10 MPa, 60° 8 MPa), inclined type N (0°/30°/ 90°, 8 MPa) and inclined type H (90°, 10 MPa). The results of this paper provide crucial theoretical guidance for exploitation of Lower Cambrian black shale with hydraulic fracturing in the Feng’gang No. 3 block of northern Guizhou.