S.A IGBINERE

Efficient management of oil reservoirs requires accurate prediction of reservoir performance and optimization of recovery strategies. This study focuses on the simulation and performance analysis of a waterflooded oil field using Computer Modelling Group (CMG) software. Waterflooding, a secondary recovery method, is applied to sustain reservoir pressure and enhance oil displacement efficiency after primary depletion. In this research, a threedimensional reservoir model was constructed using geological, petrophysical, and production data, incorporating rock and fluid properties such as porosity, permeability, viscosity, and relative permeability curves. The simulation was performed using CMG IMEX, a black-oil simulator, to evaluate reservoir behavior under both natural depletion and water injection scenarios. The results from the base case simulation indicated a gradual decline in oil production rate due to reservoir pressure depletion, while the waterflooded case demonstrated a significant improvement in oil recovery performance. The initial oil production rate before flooding was approximately 1500 STB/day, which declined to 500 STB/day before water injection. After waterflood initiation, oil production increased to about 1450 STB/day, accompanied by a gradual rise in water cut from 10% to 70% over the simulation period. Cumulative oil recovery improved from 25% under primary recovery to approximately 45% with waterflooding, indicating a 20% incremental recovery due to secondary recovery efforts. The study highlights the importance of reservoir simulation tools such as CMG in designing and optimizing waterflood operations, predicting production performance, and evaluating reservoir management strategies. It concludes that waterflooding remains one of the most efficient and economical methods of improving oil recovery in mature fields when properly designed using robust simulation techniques.