Experimental Study of Flooding by Associated Gas and Surfactant of Deposits of Ultra-Low-Permeable Shale Oil

Abstract

Summary The core flooding experiments with ultra-low permeable consolidate oil samples are performed with hydrocarbon gas injection and surfactant water solvent injection. The comparison of the effectiveness of both experiments was done. We have considered different surfactants which were tested on their thermal stability in reservoir conditions, ability to decrease capillary pressure and interfacial tension between oil and water phases and contact angel between core and oil phase. Then the two best surfactants were tested via emulsification, in order to avoid stable emulsions. Then critical micelle formation concentration was estimated. The gas composition of the associated gas was tested by slim-tube with the oil sample in order to achieve miscibility and estimate the minimal miscibility pressure. The gas flooding core tests were fulfilled in miscible mode. The X-ray scanning and computer tomography where used as additional equipment to estimate the displacement dynamic. Two core flooding experiments have shown 75% of oil displacement with associated gas and 52% of oil displacement with surfactant solvent. Gas flooding gives higher displacement coefficient and better displacement characteristics. Unlike water fluids, gas has the potential to easily propagate within tight rock, thus it is a promising EOR method for ultra-low-permeable shale oil reservoir.