Influence of Well-Pattern Geometry on Alkali–Surfactant–Polymer Flooding Performance in a Heterogeneous Niger Delta Sandstone Reservoir: A Numerical Simulation Study

Abstract Enhanced oil recovery (EOR) techniques play a critical role in maximizing hydrocarbon recovery from mature reservoirs where conventional production methods have become ineffective. Among chemical EOR methods, alkali–surfactant–polymer (ASP) flooding has demonstrated significant potential for improving displacement efficiency and mobilizing residual oil. This study evaluates the performance of waterflooding and ASP flooding under different well-pattern configurations in a heterogeneous Niger Delta sandstone reservoir using the Computer Modelling Group’s STARS simulator. Three injection patterns—five-spot, direct-line, and staggered-line—were investigated to determine their influence on cumulative oil production, recovery factor, water cut, and reservoir pressure behavior. Relative permeability curves were generated using Corey empirical correlations and validated against experimental measurements. Simulation results indicate that ASP flooding significantly outperformed conventional waterflooding across all investigated scenarios. Recovery factors of 58.55%, 69.31%, and 73.33% were obtained for the five-spot, direct-line, and staggered-line ASP flooding configurations, respectively, compared with 36.17%, 39.68%, and 35.26% for the corresponding waterflooding cases. The staggered-line ASP flooding pattern achieved the highest cumulative oil production of 20.55 MMSTB and demonstrated superior sweep efficiency throughout the production period. The results demonstrate that well-pattern optimization is a critical factor in maximizing chemical EOR performance in heterogeneous sandstone reservoirs. The findings further suggest that combining ASP flooding with optimized injector–producer arrangements can significantly improve hydrocarbon recovery and may provide useful insights for future studies involving CO₂-enhanced oil recovery and carbon storage applications.