Lattice-Boltzmann Pore-Scale Simulator for Complex Multiphase Flows in the Digital Twins of Reservoir Rocks

Abstract Prediction of multi-phase flows in tight pore materials is a great importance for oil recovery by filtration, CO2 sequestration, and acid stimulation of carbonate reservoirs. The paper presents a fast highly scalable Lattice-Boltzmann simulator of multiphase flows in the digital twins of reservoir rocks obtained by computer tomography and a validation against experimental data. First, the method is tested against single-phase permeabilities of sandstones and carbonates, including very tight Achimov formations. Then, different models of interfacial interactions are applied in simulations of concurrent multiphase flows. A novel simulation protocol is introduced: a preliminary drainage simulation is followed by a series of two-phase concurrent flow simulations, which mimic filtration. In each filtration simulation the ratio between the volumes of the two phases set at the inflow boundary and thus the saturation—permeability curves are obtained. The protocol is computationally cheaper than the current practices and provides a precise control over saturation levels. The parameterization of the LB models accounts for the ratio between the interfacial forces and inertia, which is especially important in imbibition simulations. By adding spontaneous imbibition cycles between the steady state permeability measurements, the fluid is relaxed towards its global free energy minimum, which affects the irreducible water and oil ratios. Quantitative agreement with experimental relative permeabilities is achieved. Then the simulation methodology is adopted to study the dynamics of liquid-gas system and compared with the experiment on foam drainage, with very reasonable results.