OPTIMAL WELL DESIGN FOR WATER DUMPFLOOD

Abstract

Water dumpflood is a proven technology that can help maintain reservoir pressure and improve oil production. This process helps save capital and operating costs of pump and injection pipeline. However, due to limited control of the amount of water being dumped, oil recovery from water dumpflood may not be very high. Thus, there is a need to design appropriate water dumpers and oil producers in order to displace oil as much as possible in such situation. In this study, a numerical reservoir simulator was used to compare the performance of different well types (vertical versus horizontal dumpers and producers), well lengths (in the case of horizontal penetration in the oil zone), and starting time for dumpflood for different aquifer sizes. The reservoir simulation model is based on reservoir and fluid properties of an onshore oilfield in Thailand. For well type, results from simulation indicate that vertical dumper and horizontal producer can yield oil recovery of 30.78% while oil recovery of vertical dumper and vertical producer is 14.46%. Simulation results also indicate that longer horizontal well length yields higher oil recovery and less water production. For starting time of water dumpflood, it does not have a significant effect on oil production. In summary, water dumpflood has better production performance than natural depletion and worse performance than conventional waterflood.