Abstract: To investigate the effects of varied operational parameters on hydraulic fracturing in deep shale reservoirs, a three-dimensional numerical model for multi-cluster hydraulic fracturing in deep shale formations was established, anchored in logging data collected from a 3 500 m deep shale reservoir site within the Longmaxi Formation of the Sichuan basin. The micro-statistical damage finite element method was integrated into this model, which was tailored to the specific conditions and geological features of hydrocarbon-bearing reservoirs. Simulations were carried out separately to examine the effects of differing perforation cluster spacing, fracturing fluid viscosity, and number of perforation clusters. The variations in fracture initiation pressure, acoustic emission energy, and fracture propagation patterns under different operational parameters were analyzed. Specific results showed: When the number of perforation clusters was 7 and the viscosity of the fracturing fluid was 1 mPa·s, the cluster spacing increased from 6 m to 12 m, the fracture initiation pressure linearly increased from 16.47 MPa to 22.14 MPa, the acoustic emission energy increased from 10.27 kJ to 13.98 kJ, and the fracture propagation areas on the horizontal and vertical planes significantly increased. When the cluster spacing was 10 m and the viscosity was 1 mPa·s, the number of perforation clusters increased from 3 to 9, the fracture initiation pressure increased from 10.65 MPa to 25.36 MPa, the acoustic emission energy increased from 6.43 kJ to 16.09 kJ, and the fracture propagation area increased. When the cluster spacing was 10 m and the number of clusters was 7, the viscosity of the fracturing fluid increased from 1 mPa·s to 6 mPa·s, the fracture initiation pressure decreased from 20.08 MPa to 12.14 MPa, the acoustic emission energy decreased from 13.06 kJ to 7.18 kJ, the fracture propagation area decreased and the shape tended to be circular in the horizontal and vertical planes.

Key words: deep shale reservoir, hydraulic fracturing, numerical simulation, construction parameters, fracture propagation, Sichuan basin