Pore-scale investigation of petro-physical fluid behaviours based on multiphase SPH method

In this work, a series of microscopic simulations are conducted to investigate the effect of wettability, flow rate and surface tension in porous system by using pairwise force smoothed particle hydrodynamics (PF-SPH) method. Firstly, a novel inflow and outflow boundary is introduced in the SPH framework. The overall proposed model is verified by two benchmarks. The test cases are run in the two dimensional heterogeneous porous media. The effect of wettability, flow rate and surface tension to the macroscopic parameters such as relative permeability and residual oil saturation are thoroughly examined. Through our simulations, we conclude that (i) the type of residual oil changes with contact angle; water wetting porous media has a higher level of waterless oil recovery period and the discrepancies of ultimate oil recovery efficiencies happen before water phase breaks through the outlet of porous media; the residual oil saturations present excellent linear correlations with contact angles; (ii) it's better to increase the flow rate at the high water cut stage (eg f(w) = 90%) in hydrophilic porous media and rise the flow rate at early water cut stage (eg f(w) = 0%) in lipophilic porous media; increasing the flow rate dramatically shortens the effective production time in strong oil wetting porous media; (iii) decreasing the surface tension could change the type of residual oil, which leads to the further extraction of oil film and cluster residual oil.