Abstract

Radial borehole fracturing is a kind of reservoir transformation technology combining radial borehole and hydraulic fracturing. The research on the influencing mechanism and main control factors of fracture propagation in radial borehole fracturing is still incomplete. This paper establishes a three-dimensional fracture propagation model of radial borehole fracturing based on the discrete lattice method, and carries out numerical simulation. The guidance strength (I) was introduced, the larger the value of I, the stronger the ability of radial borehole to guide the targeted propagation of hydraulic fractures. As azimuth of radial borehole increases, the distance of fracture starting deflection becomes smaller and the I decrease. Azimuth ≤45° is conducive to better guide hydraulic fractures in radial borehole; The radius and length of radial borehole are proportional to the I; Smaller radial borehole spacing (<1.5 m) is more conducive to radial borehole guided hydraulic fracture targeted propagation; When horizontal in situ stress difference is large, the stress difference will seriously affect the radial borehole guiding hydraulic fractures; With the increase in elastic modulus, permeability and Poisson's ratio, the I decreases. But the influence of Poisson's ratio is small; Larger displacement is conducive to the propagation of hydraulic fractures along radial borehole direction; The viscosity is about 50 mPa·s, and the radial borehole has the best guidance for hydraulic fractures; the gray correlation analysis results show that the three radial borehole parameters, radius, length, and azimuth, have the strongest correlation with the I.