Case Study of Gravity and Power Assisted Dump Floods Implemented in a Mature Oil Field

Abstract

Dump-flood is a powerful and convenient recovery technique that maintains a reservoir pressure where an aquifer and an oil leg are perforated in the same well. In gravity assisted dump-flood, GADF, water from a shallow waterbed above is injected by its own hydrostatic weight into an underneath oil bearing formation. In a power assisted dump-flood, PADF, the injection pressure from the waterbed maybe enhanced by utilizing electrical submersible pumps, ESP. In this work, both GADF and PADF were implemented in a mature depleted reservoir block for a quick pressure maintenance program. Three injectors were drilled and completed to have both the upper Gir and lower Gir intervals in communication. ESPs were installed in three wells to enhance the water gravity effect. Recovery Factor, RF, increased from 8.92% before the implementation of dump- flooding to 10.68% after the implementation with no signs of plugging or scaling in the reservoir. Reservoir pressure increased by 213 psi due to dump-flood implementation and oil production rate increased in one of the wells by 1629 barrel per day at an optimum choke size of 24/64 in. Dump-flooding is an excellent alternative to conventional water injection as the pilot injectors significantly stopped rapid pressure decline and improved production rates.