Coarse-graining of CFD-DEM for simulation of sand production in the modified cohesive contact model

Sand production is an important issue for many hydrocarbon recovery applications in unconsolidated reservoirs. The model using the computational fluid dynamics coupled with discrete element method (CFD-DEM) can capture micro-scale features of sand transport problems. In this study, coarse-graining methods of a three-dimensional CFD-DEM model are developed to investigate the sand production phenomenon. The modified cohesive contact model is utilized for the simulations with a sample based on particle size distribution obtained from the unconsolidated sandstone reservoir in Kazakhstan. The derivation of scaling from the fine model to the coarse model is presented rigorously. The original (fine scale) model is validated to the laboratory results including the cumulative sand production rate. The results of the original model is compared to the same statistic weight (SSW) and the same size parcel (SSP) coarse-gained models. The original and coarse-grained models show good agreement in the fluid streamlines, fluid and particle velocities. In terms of sand production rate, the SSW model results are more accurate than the SSP model. Moreover, the particle size distribution of the produced particles of the SSW model is consistent with the results of the original particle model. The SSP model performs better in terms of speedup by accelerating the original model up to 9.4 times in parallel computing.