Simulation of Fluid Flow in Induced Fractures in Shale by the Lattice Boltzmann Method

Abstract

With increasing interest in unconventional resources, understanding the flow in fractures, the gathering system for fluid production in these reservoirs, becomes an essential building block for developing effective stimulation treatment designs. Accurate determination of stress-dependent permeability of fractures requires time-intensive physical experiments on fractured core samples. Unlike previous attempts to estimate permeability through experiments, we utilize 3D Lattice Boltzmann Method simulations for increased understanding of how rock properties and generated fracture geometries influence the flow. Here, both real induced shale rock fractures and synthetic fractures are studied. Digital representations are characterized for descriptive topological parameters, then duplicated, with the upper plane translated to yield an aperture and variable degree of throw. We present several results for steady LBM flow in characterized, unpropped fractures, demonstrating our methodology. Results with aperture variation in these complex, rough-walled geometries are described with a modification to the theoretical cubic law relation for flow in a smooth slit. Moreover, a series of simulations mimicking simple variation in proppant concentration, both in full and partial monolayers, are run to better understand their effects on the permeability of propped fractured systems.