LATTICE BOLTZMANN SIMULATION OF DYNAMIC WETTABILITY ALTERATION AND TWO-PHASE DISPLACEMENT IN POROUS MEDIA INDUCED BY POLAR-COMPONENT DESORPTION

During high-flux water flooding in marine sandstone reservoirs, the continuous desorption of polar components from rock surfaces is a key mechanism that induces dynamic wettability alteration and controls pore-scale oil-water transport and residual oil remobilization. In this study, a lattice Boltzmann model for oil-water two-phase flow in porous media was developed by coupling flow, mass transfer, and adsorption processes. Within a multiple-relaxation-time Shan-Chen multicomponent framework, a solute transport model and an improved Langmuir adsorption-kinetic boundary were introduced, enabling the explicit coupling among the dynamic adsorption/desorption of polar components, contact-angle evolution, and two-phase displacement response. Based on this framework, the pore-scale oil-water transport behaviour under dynamic wettability alteration was systematically investigated, and the effects of the oil-water viscosity ratio, the initial concentration of polar components, pore-throat structure, and mineral-composition heterogeneity were analysed. The results show that, under dynamic wettability alteration, the high-flux water-flooding process can be divided into two stages: dominant flow-channel formation with oil breakup, and wettability-evolution-driven remobilization of dispersed residual oil. In the late stage of high-flux water flooding, the sustained increase in oil recovery is jointly governed by wettability-driven detachment and capillary-equilibrium disturbance. A moderate oil-water viscosity ratio is more favourable for balancing early sweep efficiency and late-stage mobilization. Within the concentration range considered in this study, the initial concentration of polar components mainly affects the local desorption behaviour and the adhesion state of residual oil, while its effect on the overall displacement pattern is limited. In real porous media, the pore-throat structure determines the formation mode of dominant flow channels and the spatial extent of wettability evolution, while mineral heterogeneity affects residual oil retention and remobilization by regulating local interfacial responses. Stronger pore-throat connectivity and better structural homogeneity facilitate the propagation of wettability alteration from dominant flow channels toward adjacent trapped zones, thereby improving the two-phase flow capacity. This study provides a pore-scale theoretical basis for remaining-oil potential evaluation and strategy optimization of high-flux water flooding in marine sandstone reservoirs.