experimental investigation of high-pressure and high-temperature water-alternating-gas (wag) process in the low permeability rocks

Water-alternating-gas (wag) injection has been known as a valuable and impactful method for increasing the oil recovery. it should be noted that its successful implementation depends on the in-depth knowledge about the factors which are affecting the process. in this regard, it is vital to conduct a series of detailed experiments at the reservoir condition. it this study, first, the miscibility of methane and associated gas was determined through conducting slim-tube experiments. minimum miscibility pressure of methane and associated gas was 6933 and 5672 psig, respectively. secondly, the gas injection and water flood tests were conducted to better analyze the results, and have a better understanding of wag outcomes. next, a wag injection experiment was performed to comprehend the effect of wag injection in the low permeability rocks. moreover, a test was designed to use wag injection as a tertiary enhanced oil recovery (eor) method. results show better performance of wag injection from either case of gas injection (about 6% and 26% better than associated gas and methane, respectively) and water flood. in addition, using wag injection as a tertiary method had the best performance among all the experiments. an initial water flood followed by a wag injection led to a recovery of 76.45% which was about twenty percent higher that wag injection solely, and about 35% higher that water flood.