Numerical study on the law of fracture propagation in supercritical carbon dioxide fracturing

Abstract

Compared with conventional hydrofracturing fluid, SC-CO2 has the merits of no water sensitivity and effective carbon dioxide storage. At present, the research on the fracture initiation mechanism of SC-CO2 fracturing is still at the exploring phase. This paper conducts a detailed study on the fracture initiation mechanism of SC-CO2 fracturing, and establishes a fracture initiation and propagation model of flow-stress-damage coupling according to damage mechanics. A series of numerical simulation studies have been carried out on the rock physical parameters, fracturing construction parameters, natural fracture distribution and other factors that affect the fracture propagation of the reservoir to provide a reference for the SC-CO2 fracturing construction design. The findings suggest: the lower formation permeability, the less SC-CO2 filtration loss, and the larger total fracture length and width; SC-CO2 is easier to improve the reservoir continuity and result in a complex fracture network; The lower the viscosity of SC-CO2, the larger total length of fractures, and the more complex the fracture network; As the delivery of pump increases, the width of fracture continues to increase, and the total fracture length decreases; SC-CO2 has a better effect on communicating natural fractures and porous media, and the fracture network is more complex.