Simulation of proppant conductivity test: effect of particle size dispersion

Abstract

A conductivity test of proppant material consists in confining a sample of the granulate at high pressure and then set a flow through the pack. The proppant particle size is the main variable controlling conductivity, but also particle size dispersion is considered important. Even though several studies consider mixtures of proppants of different meshes, there are not clear evidences as to whether the changes in conductivity with respect to a monosized proppant are caused by the mix itself or by the overall change in mean particle size. Hence, we use numerical simulations to answer the question: Does particle size dispersion significantly affects the proppant conductivity if mean particle size is kept the same? We measure conductivity and permeability by simulating (via a coupled Computational Fluid Dynamics–Discrete Element Method) the flow of water through binary granular packs. We find that size dispersion does not affect conductivity (in the dispersion range explored) if the mean particle size is conserved. However, we observe that in a binary mixture the large particles are subjected to larger stresses than in a monosized system, which makes them prone to crushing.