Detection of Water Encroachment into a Marginal Field Oil Reservoir for Ultimate Recovery

Abstract One key element of effective well and reservoir management is the application of numerical simulators to solving complex and challenging reservoir issues like aquifer water encroachment into an oil reservoir. Hydrocarbon reservoirs are often in contact with an aquifer that provides pressure support through water encroachment. It is common to speak of edge-water and bottom-water while discussing water encroachment into a reservoir. Bottom-water occurs directly beneath the oil zone while edge-water occurs off the flanks of the structure at the edge of the oil zone. Thus, the prediction of reservoir performance and behaviour usually requires an accurate model. A single-well numerical simulation model was developed using Eclipse® software to detect aquifer water encroachment into an oil reservoir, predict the performance, behaviour and ultimate recovery of the reservoir. Five scenarios of a marginal field reservoir were modeled: no water influx, bottom-water influx, edge-water influx and combined edge- and bottom-water influx. Results obtained from the numerical simulation model were validated with an analytical model MBAL. The results shows that the reservoir depletion without water influx gave the lowest oil recovery and fastest rate of pressure decline, bottom-water influx and combined edge- and bottom-water influx gave the same oil recovery factor while edge-water influx gave the highest oil recovery factor and low rate of pressure decline. The fifth scenario investigated why edge-water influx gave the highest oil recovery factor than the combined edge- and bottom-water influx.