Perpustakaan Digital ITB

Minas is a mature waterflood field where about 95% of its production comes from base business process. Reservoir management is an important key to make sure the production meets the target. During the waterflood review cycle, mainly three parameters mainly reviewed: VRR, WOR (water oil ratio) and GOR (gas oil ratio). Voidage Replacement Ratio (VRR) or sometimes also called FIFO (fluid in fluid out) is a balancing factor monitored during waterflood recovery. WOR and GOR are results of VRR designed earlier for a particular waterflood field. Water injection target, workover, fluid optimization will refer to VRR for execution. In the oil industry common practice , the best VRR for light oil is equal to 1. Some studies supported the idea but other study said that it should be less than 1. Minas has been pattern waterflooded for about 20 years. There is nothing more luxurious than having real data from the field. A statistical method is used to analyze these data to identify what is the optimum VRR. Since Minas is a big field, doing simulation for sensitivity of VRR will take a long time and also difficult to see the impact of of VRR changes in one small pattern. In this thesis, a representative part of the field, which has properties like Minas, is used as a dummy field model, with one 5-spot pattern in that field. Literature, statistics and Simulation method agree that VRR is closely related to reservoir pressure. The optimum pressure for recovery should be less than the initial reservoir pressure but higher than the bubble point pressure. VRR design is unique for a particular field. For Minas, based on the dummy field model simulation, the recommended VRR should be between 0.8 and 1.