Lattice Boltzmann Simulations of the Interface Dynamics During Two-Phase Flow in Porous Media

Abstract

Abstract: This paper systematically investigates the impact of porous mediadisorder and its coupling with flow rates, favorable andunfavorable viscosity ratios, as well as surface tensions on thedynamics of interfaces development during two-phase drainage flow.A special attention is paid to establishing relationship betweenthe dynamics of fluid–fluid and fluid–solid interfacial lengths,the pore selectivity and the displacement efficiency using imagingof fluids distribution in porous media. As samples of study, weused artificially generated models of porous media with differentdisorder parameters and with two-types of pore-channels systems"— hexagonal and square. In our methodology, the disorderdefines the range of grain size distribution and is applied tocontrol the pore size range. For two-phase flow simulation, thelattice Boltzmann equations and the color-gradient model areapplied. It was established the linear relationships betweenfluid–fluid and fluid–solid interfacial length and saturation ofthe invaded fluid. During numerical simulations at differentdisorders, the lack of disorder effect on the fluid–fluidinterface dynamics and negative disorder impact on thefluid–solid interface dynamics was found. When varying the flowparameters, it was identified that the increase in thefluid–fluid interface dynamics is accompanied by a decrease inthe fluid–solid interface dynamics. For all displacementmechanisms considered in this paper, except capillary fingering,an inverse relationship between pore selectivity and pore number,involved in displacement, was detected. We found a shift of poreselectivity towards higher values with increasing disorder whichnegatively impacts on the displacement efficiency. In capillaryfingering regime, a strong tendency to minimize fluid–fluidinterfacial length with surface tension explains the lack ofrelationship between pore selectivity and pore number which leadsto bad predictable displacement efficiency in this regime.