Flow behaviors of ellipsoidal suspended particles in porous reservoir rocks using CFD-DEM combined with multi-element particle model

摘要

The flow behaviors of suspended particles and pore fluids in porous reservoir rocks have attracted much attention in the fields of oil drilling and oilfield development. The effects of aspect ratios and volume ratios on transient flow behaviors of ellipsoidal suspended particles and fluid are investigated by CFD-DEM method combined with multi-element particle model. Simulation results show good agreements with experiments by Ten Cate et al. and classical Ergun equation, respectively. Suspended particles undergo the process of acceleration, migration, aggregation, collision, deceleration, plugging, deposition or flow out carried by fluid. The disturbance of fluid velocity at the gathering place of suspended particles is intensified. The rotational and translational kinetic energies of ellipsoidal particles are larger than spherical particles, and the out-flow rate shows a trend from rise to decline with time. The rotational kinetic energy in x direction is less than those in the other two directions, while the translational kinetic energy exactly shows an opposite trend. The mean granular temperature firstly increases and then decreases with time, and the pressure drop for spherical particles within the channel is the largest. For binary ellipsoidal suspended particles existing in the porous rock, with the increase of the volume fraction of small particles, the rotational kinetic energies of the large particles decreases while that of small particles increases. The deposition of large particles is obvious at the inlet and the lower half of the porous rock under gravity. Increasing the volume fraction of small particles, the pressure drop decrease while the absolute permeability and out-flow rate increase.