Combined Water Dumpflood with Water Injection into Oil Reservoir

Abstract

The major advantage of water dumpflood is that there is no cost incurred by water injection. However, water dumpflood generally results in lower oil recovery when compared with conventional waterflooding due to limited amount of water cross-flowing from the aquifer into the reservoir. Conventional waterflooding, on the other hand, requires tremendous amount of water injection from surface that incurs large operating costs. To utilize the benefits of the two methods, the different ways to combine water dumpflood with water injection into oil reservoir were investigated: water dumpflood followed by water injection (schedule 1), simultaneous water dumpflood and injection via different wells (schedule 2), and simultaneous water dumpflood and injection via different wells followed by conversion of dumpflood well to water injection well (schedule 3). A simple reservoir model having the properties of one of the oil fields in Thailand was constructed using ECLIPSE100 reservoir simulator to simulate three production scenarios: conventional waterflooding, water dumpflood, and combined water dumpflood with water injection. Additional parameters which are types of production, injection, and dumping wells (vertical versus horizontal) and liquid production rate were also investigated. The simulation results clearly illustrate the benefits of combined water dumpflood with injection (schedule 1) that it can achieve similar oil recovery with the conventional waterflooding but requires much smaller amount of injected water. A combination of one vertical producer and two vertical dumping/injection wells yields the highest oil recovery for the three production scenarios. High liquid production rate also provides better production performance compared to low liquid production rate.