EFFECT OF WATER INFLUX ON RESERVOIR PERFORMANCE PREDICTION

ABSTRACT

Petroleum reservoirs are commonly surrounded by water aquifers at their edges or bottoms, which serve to maintain reservoir pressure by allowing water to flow in when there's a drop in pressure. When the pressure in a petroleum reservoir decreases, the adjacent water aquifer responds by providing an influx or encroachment of water to counteract the pressure decline. Calculating the water influx is crucial in various aspects of reservoir engineering, including material-balance studies and the design of pressure maintenance strategies. Numerous models have been put forth by different researchers to estimate the total water influx into a reservoir over time. The van Everdingen and Hurst method is generally considered a reliable approach for calculating water influx behavior into a reservoir, other models have also been developed. In this study, we employed Excel regression analysis and the van Everdingen and Hurst unsteady state model to determine the water influx into "Reservoir X" over a ten-year period. Additionally, we used this data to predict the reservoir's future performance from 2023 to 2032. The results of our analysis confirmed that the reservoir is primarily driven by water, and it initially contained 100 million barrels of original oil in place. Over the decade, the reservoir pressure declined from 1400 psi in 2023 to 500 psi in 2032. Furthermore, the cumulative oil production increased from 13,946,000 barrels in 2023 to 22,946,000 barrels in 2032. Simultaneously, the cumulative water influx rose from 14,766,709.44 barrels in 2023 to 40,004,115.28 barrels in 2032.