Investigating the impact of proppant embedment and compaction on fracture conductivity using a continuum mechanics, DEM, and LBM coupled approach

In this study, a numerical modeling approach was developed to advance the understanding of fracture conductivity at different effective stresses, proppant sizes and diameter distributions. The continuum mechanics code (e.g., FLAC3D) was employed to compute proppant embedment and DEM code (e.g., PFC3D) was used to calculate the proppant compaction and rearrangement. LBM simulation was performed on the evolved proppant pack to compute the time-dependent permeability of the proppant pack. Proppant packs with 20/40 and 30/50 mesh sizes were generated using the same average diameter but different diameter distributions. Specifically, we used the coefficient of variation (COV) of diameter (defined as the ratio of standard deviation of diameter to mean diameter) to characterize the heterogeneity of particle size. The influences of proppant sizes, distribution patterns and rock properties, on fracture conductivities were extensively studied. Simulations showed that, under the same effective stress, a proppant pack with a smaller diameter COV has higher fracture width, permeability and conductivity. Fracture conductivity increases with increasing proppant size but decreasing fracture closure stress. Proppant embedment increases with the decrease of rock formation’s stiffness. The results of this research revealed various characteristics of proppant packing that may affect the hydraulic conductivity of proppant-supported fractures.