Perpustakaan Digital ITB

Indonesia is experiencing a scarcity in oil production while the demand for it is steadily increasing by 3% each year since 2010. The counteraction that can reduce the severity of this problem is by performing Enhanced Oil Recovery (EOR). Low Salinity Water Injection (LSWI) is one of the EOR methods that have become a centre of attention in the past few decades. This emerging EOR is believed to offer a significant increase in oil recovery compared to conventional waterflooding with other advantages compared to other EOR methods. However, there are still limited studies in optimising the application of LSWI in one field and the underlying mechanism of this method is still open for discussion. From the studies conducted, the most popular underlying mechanism proposed is wettability alteration caused by Multi-Component Ionic Exchange (MIE) and Double Layer Expansion (DLE). This mechanism could happen differently throughout the reservoir. Thus, the placement of the well can be used to optimise LSWI method. This study is conducted to design the optimum well injection pattern, placement and number (system) at the “T” Structure in “S” Field, Indonesia. The well injection system used in this study are peripheral and regular injection configuration. The best well injection system will be determined based on the maximum oil recovery. Additionally, Multi-component Ionic Exchange (MIE) as one of the underlying mechanisms will be modeled by relative permeability shifting. The MIE effect is studied by varying the distribution of the CEC value throughout the reservoir model to further determine the optimality of the well injection system. The distribution of CEC values is possible by implementing the study of Breeuwsma (1986); Juhasz (1981); and da Silva et al. (2018). The “T” Structure is identified as a sandstone reservoir with mix-wet wettability which makes it suitable for LSWI implementation. A reservoir simulation study using a compositional simulator, CMG GEM™, was performed to optimise the implementation of LSWI based on the well injection system and CEC distribution to generate maximum oil recovery. The results of this study concluded that the implementation of LSWI in this structure needs 4 production wells and 4 injection wells (including existing wells) in the configuration of peripheral injection to be optimum. This optimum case could deliver around 48.21% of the oil recovery factor or additional 0.86 million barrels of oil cumulative production compared to the base case. Therefore, low salinity water injection is highly suggested to be implemented in this reservoir.