Experimental Investigation of High-pressure and High-Temperature Water-Alternating-Gas (WAG) Process in the LowPermeability Rocks

Water-Alternating-Gas (WAG) injection has been known as a valuable and impactful method forincreasing the oil recovery. It should be noted that its successful implementation depends on the indepthknowledge about the factors which are affecting the process. In this regard, it is vital to conducta series of detailed experiments at the reservoir condition. It this study, first, the miscibility of methaneand associated gas was determined through conducting Slim-Tube experiments. Minimum miscibilitypressure of methane and associated gas was ۶۹۳۳ and ۵۶۷۲ psig, respectively. Secondly, the gasinjection and water flood tests were conducted to better analyze the results, and have a betterunderstanding of WAG outcomes. Next, a WAG injection experiment was performed to comprehend theeffect of WAG injection in the low permeability rocks. Moreover, a test was designed to use WAGinjection as a tertiary enhanced oil recovery (EOR) method. Results show better performance of WAGinjection from either case of gas injection (about ۶% and ۲۶% better than associated gas and methane,respectively) and water flood. In addition, using WAG injection as a tertiary method had the bestperformance among all the experiments. An initial water flood followed by a WAG injection led to arecovery of ۷۶.۴۵% which was about twenty percent higher that WAG injection solely, and about ۳۵%higher that water flood.

Keywords:

Water-Alternating-Gas (WAG) , Core flood , Enhance Oil Recovery (EOR) , Minimum Miscibility Pressure , Slim-Tube