Experimental Investigation of Water Alternating CH4-CO2 Mixture Gas Injection to Light Oil

In this work effect of composition changes of injection gas, CH4 + CO2, on the performance of immiscible WAG injection in light oil, 41 oAPI, which has been rarely attended in the available literature is investigated. Presence of CO2 helps to reduce the MMP of CH4 significantly. Core flood experiments are conducted at reservoir conditions and fixed flow rate of 0.5cc/min on a sandstone sample with the brine concentration of 5000 ppm, and the influence of injection gas composition as well as WAG ratio on oil recovery is investigated. Different mole percents of methane in mixture, 0%, to 100% are examined, and the tests continued to ten alternate cycles with a slug size of 0.1 pore volumes and a WAG ratio of 1:1 are injected. In addition, the WAG ratios of 1:2 and 2:1 at fixed injected gas composition of 50% are investigated. The results showed that increasing the mole percent of CO2 increases the oil recovery and it has been found that there is an optimum WAG ratio of 1, in which maximizes the oil recovery. The results of this work can be helpful for design of successful water alternating CH4-CO2 mixture gas injection in light oil reservoirs.