A new relative permeability model considering multiple effects and implications for tight reservoir development from energy utilization perspectives

Relative permeability is a critical parameter for the efficient development of tight oil reservoirs. However, fluid flow in tight reservoirs is strongly affected by near-surface viscosity, boundary layers, flow slippage, and dynamic wettability, which are only partially considered in existing models, thereby limiting their reliability. Moreover, previous studies on reservoir energy replenishment have mainly focused on changes in reservoir properties or overall replenishment performance, while the utilization efficiency of replenished energy for oil production remains insufficiently understood. In this study, a novel relative permeability model incorporating these multiple flow effects is developed and validated against experimental data. The impacts of tight-reservoir flow mechanisms on relative permeability are systematically analyzed, and their implications for energy utilization during reservoir development are investigated through numerical simulation. The results show that increasing oil viscosity enlarges the oil film thickness, reduces oil-phase flow capacity, and relatively enhances water-phase flow capacity. The water-phase relative permeability predicted without near-surface viscosity effects is lower than that obtained when these effects are included, and this discrepancy becomes more significant at higher oil viscosity. Increasing effective-driving pressure enhances water-phase relative permeability, decreases irreducible water saturation, and broadens the two-phase flow region. Neglecting multiple flow effects leads to underestimation of tight-reservoir productivity. For efficient utilization of replenished energy, a small pressure drawdown is recommended during the initial flowback and early production stages, followed by a larger drawdown in the subsequent production stage. This work provides theoretical guidance for optimizing tight oil reservoir development.