Mechanism study on hydraulic fracture initiation and propagation in basalt reservoir

ABSTRACT: Significant achievements have been made in oil and gas production in the Longtan Formation basalt reservoir in the Shunan area of the Southwest Oil and Gas Field in Sichuan, China. Hydraulic fracturing technology is the key to this result. It can construct complex fracture networks to increase the conductivity of horizontal wells and the production. Therefore, it is necessary to study how to improve the fracturing results in basalt reservoirs. In this paper, True triaxial hydraulic fracturing experiments were conducted with basalt outcrops. Fracture morphology and fracturing pressure curve were analyzed. A numerical model of fracture propagation based on the phase-field method is proposed to simulate the fracturing in basalt reservoirs. The results show that: the rock has undergone brittle fracture during the basalt hydraulic fracturing process. The horizontal ground stress difference and fluid viscosity have impacts on hydraulic fracture. Through this study, the characteristics of hydraulic fracturing fractures under different formation conditions were obtained. The test results provide a reference for the optimization of basalt formation volume fracturing parameters.