Analisis Konsentrasi Injeksi Alkali-Surfaktan-Polimer dan Slug Size pada Reservoir High Water Cut Menggunakan CMG

Abstract

High water cut is a major challenge in mature oil fields because prolonged waterflooding reduces oil production efficiency while leaving a significant amount of residual oil trapped in the reservoir. Alkaline-Surfactant-Polymer (ASP) flooding is one of the most promising chemical Enhanced Oil Recovery (EOR) methods, as it improves oil recovery by reducing interfacial tension, enhancing mobility control, and increasing sweep efficiency. This study aims to evaluate the effects of ASP concentration and slug size on oil production performance and to determine the optimum injection scenario for a heterogeneous high water cut reservoir. Reservoir simulation was conducted using Computer Modelling Group (CMG) after an EOR screening process identified ASP flooding as the most suitable recovery method. Sensitivity analyses were performed using alkali concentrations of 0.25, 0.75, and 1.25 wt%, surfactant concentrations of 0.30, 0.40, and 0.50 wt%, polymer concentrations of 0.07, 0.09, and 0.11 wt%, and slug sizes of 0.2, 0.4, and 0.6 PV. The simulation results demonstrate that increasing ASP concentration enhanced oil displacement efficiency by promoting in-situ surfactant formation, reducing interfacial tension, and improving mobility ratio. Larger slug sizes prolonged chemical contact with the reservoir, resulting in higher cumulative oil production and recovery factor. The optimum scenario was achieved using the A3S3P3 formulation (1.25 wt% alkali, 0.50 wt% surfactant, and 0.11 wt% polymer) with a 0.6 PV slug size, yielding a cumulative oil production of 1,770,989.5 bbl and a recovery factor of 74.2%. These findings indicate that ASP concentration primarily affects peak oil production, whereas slug size has a greater influence on long-term oil recovery performance.