3D Multilayer Physical Modeling for Waterflood Optimization in High Water-Cut Reservoirs

Water injection remains the primary technique for oil field development, significantly enhancing the economic viability and crude oil production of mature reservoirs. However, prolonged water flooding often leads reservoirs into an ultrahigh water-cut (WC) phase, diminishing the efficacy of conventional water flooding methods. This study aims to optimize improved oil recovery (IOR) processes in high WC reservoirs through a comprehensive three-dimensional (3D) multilayer physical simulation model under multiple water flooding scenarios. An extensive experimental framework was established, systematically investigating the effects of three crucial reservoir parameters, including the water injection rate, formation dip angle, and sand mesh size across 86 experiments. Quartz sand with varying mesh sizes (40–200 mesh), saline injection fluids, and controlled dip angles (0–45°) were employed to simulate diverse reservoir conditions. The results revealed a significant enhancement in oil recovery efficiency, increasing from approximately 51% at an injection rate of 3 mL/min to over 80% at 12 mL/min, alongside a reduction in residual oil saturation. An optimal formation dip angle of 30° was identified, achieving the highest recovery efficiency of around 88% by leveraging gravitational segregation for uniform oil displacement. Additionally, coarser sand meshes (40–80 mesh) consistently outperformed finer meshes (160–200 mesh), highlighting the critical role of reservoir permeability and porosity in fluid displacement dynamics. The integrated analysis demonstrated that higher injection rates and optimal dip angles synergistically improve sweep efficiency and production stability, while unfavorable configurations lead to increased WC values and reduced economic viability. These findings highlight the necessity of a multifaceted optimization approach that integrates injection-rate modulation, well placement relative to reservoir dip, and permeability-aware layer/segment selection to maximize recovery in high WC reservoirs. In this study, the injected water was a single 40 g/L NaCl brine; engineered/low-salinity (‘smart water’) and chemical enhanced oil recovery coupling are proposed as future extensions of the present 3D physical simulation workflow rather than variables investigated here.