History Matching and Uncertainty Analysis of Peripheral Water Injection in Mature Reservoir using tNavigator Software: Study of RZ-5 South Panel at Mahakam Delta

Abstract

As an effort to achieve energy security in Indonesia, the government through SKK Migas targets total production in the oil and gas sector to reach one million barrels per day. One method to achieve this goal is the Enhanced Oil Recovery (EOR) method. To maximize the Enhanced Oil Recovery (EOR) method, a reservoir simulation is carried out first. Reservoir simulation is a method used to predict a reservoir's ability to produce hydrocarbon reserves using mathematical models. In this study, history matching was carried out before development on the RZ-5 South Panel located at Abuoti Field in the Mahakam Delta, East Kalimantan, which in this field has a history of peripheral water injection in mature reservoirs. To carry out history matching, a literature review is carried out and data is collected which will be used as input parameters in the tNavigator software. The parameters that are objective in this study are Pressure Matching and Saturation Matching by carrying out uncertainty analysis on each variable that impacts reservoir performance, namely Reservoir Properties, MINPV, Aquifer Strength, Fluid Contact, Corey Function, Constraints, and Fluid Saturation. Apart from that, sensitivity to production and injection data is also needed to maximize history matching. In pressure matching, results were obtained that was not matching fully even though uncertainty had been carried out, which was most likely caused by the condition of the reservoir in the RZ-5 South Panel, there are many facies of bars, especially in Region B and Region C. These facies of bars cause specific pressure differences on the reservoir grid. Meanwhile, in saturation matching, the Oil Production Mismatch is 2.1% and the Gas Production Mismatch is 52.6%. Gas production mismatch has occurred since 1977 which are 2 possible causes, there is an adjusting value of Solution Gas (Rs) and the allocation of gas production that are contaminated by production from other layers or panels. So, it is still necessary to re-approach the Solution Gas (Rs) value and approaching re-allocate gas production in each well that has a high production rate.