Perpustakaan Digital ITB

The application of enhanced oil recovery (EOR) has received significant attention due to the potentially huge amount of recoverable oil. One of the most popular EOR methods is CO2 injection. This technology has been successfully implemented in numerous numbers of projects either under the condition of miscible or immiscible. However, the selection of the most suitable injection method to adopt for specific field applications is challenging. Therefore, this study aims to do an evaluation of “B” Structure and “S” Field for CO2 injection based on several screening criteria and to determine the optimum injection methods: huff-n-puff, continuous gas injection, and water alternating gas (WAG) based on its maximum oil recovery. In this study, different injection methods including huff-n-puff, continuous gas injection, and WAG were simulated at “B” Structure “S” Field which has strong water drive, high connected reservoir, high interference among wells, and high temperature. The injection was done under immiscible condition due to the minimum miscibility pressure (MMP) is higher than the reservoir pressure. Reservoir simulation and production forecast were performed by using CMG GEM simulator based on the fluid compositional generated in CMG WINPROP. Huff-n-puff injection was conducted by injecting CO2 for 40 days, with soaking time of 14 days, production period of 3 years, and 3 number of cycles. Continuous gas injection was applied for 11 years, starts from 1st January 2024 until 1st January 2035, and a sensitivity parameter was done for its injection rate. Water alternating gas (WAG) was performed for 11 years, starts from 1st January 2024 until 1st January 2035, and a sensitivity parameter was done for WAG ratio and WAG cycle. Based on screening criteria evaluation, “B” Structure “S” Field is revealed to be compatible with CO2 injection under immiscible condition. Further screening criteria on injection method claimed that the favorable injection methods are both continuous and water alternating gas injection. While huff-n-puff asserted as less favorable, its screening score shows worthy for further investigation. Accordingly, the result of simulation shows that WAG injection methods is proven to be the optimum EOR injection methods at “B” Structure “S” Field with an additional recovery factor of 5.26% from the basecase. Another finding of this study show that huff-n-puff methods yields the least recovery factor even less recovery factor than the basecase by 0.62%. Continuous gas injection achieved an improvement on oil recovery factor, which is 0.01% from the basecase. It is inefficient to applied continuous gas injection method for “B” Structure “S” Field due to its low oil recovery improvement.