Conductivity analysis of hydraulic fractures filled with nonspherical proppants in tight oil reservoir

Abstract

Hydraulic fracturing is an effective way to exploit hydrocarbons in tight oil reservoir. The success of this technique lies on the creation of high conductivity channels for the oil and gas. Quantitative analysis of factors influencing the conductivity of propped fractures is significant for the design of the operation schedule. According to the definition of sphericity, cylindrical and planar proppants of different sphericity and sizes were presented. And disordered packs of nonspherical proppants in fractures of different widths were established by the discrete element method. The change of the proppant embedment and fracture width under different closure pressures were analyzed by the solid mechanics. During the fracture deformation, the pressure and velocity of the fluid flowing in fractures were simulated by Lattice-Boltzmann method. Based on that, the effect of the proppant size, sphericity, and the fracture width on the permeability and conductivity of hydraulic fractures were investigated. The accuracy of the model was verified by the experimental data. The simulation results show that the fracture permeability and conductivity decrease with the decrease in the rock's Young's modulus, proppant size, and sphericity, and their stress sensitivity increases with the decrease in the rock's Young's modulus and the increase in the proppant size. Increasing fracture width can improve fracture conductivity more significantly than increasing fracture permeability. The permeability and conductivity of the fractures filled cylindrical proppants are higher than that of the fractures filled with planar proppants.