The effect of alkaline\u2013surfactant on the wettability, relative permeability and oil recovery of carbonate reservoir rock: experimental investigation

Abstract

Due to the increasing demand and the price of hydrocarbon fuels, today, cost-effective enhanced recovery of oil and gas reservoirs has become one of the most interesting research topics. Since the Iranian reservoirs have a considerable potential to apply the chemical EOR processes, it seems that extensive research in this field is inevitable. One of the most important enhanced oil recovery techniques is injecting alkaline–surfactant into the reservoir. Although injecting alkaline–surfactant has been investigated in many researches, few studies reported on the effect of this process on the oil/water relative permeabilities which control the recovery performance. Today, the need for EOR processes is critical. One of the newest ideas for this respect is the concept of altering the rock wettability to more water wet. This phenomenon leads to making a path for oil in the larger routes, therefore increasing the recovery. In most cases, waterflooding has a low effect and by increasing the water production, the oil recovery becomes non-economical. In most studies, the effect of solution injection has been considered. In this study, we have investigated the effect of chemicals on interfacial tension and the wettability alteration based on relative permeability curves. In this work, using three surfactants, anionic (SDS), cationic (CTAB) and nonionic (Triton X-100), with sodium carbonate alkaline, relative permeabilities, wettability, IFT and the recovery efficiency in the porous media in the core scale have been investigated. The results show that cationic surfactant has the most effect on reduction in IFT and changing the wettability to water wetness, which has 70% recovery factor. Anionic surfactant has a greater effect on the reduction in interfacial tension in comparison with nonionic surfactant. Furthermore, nonionic surfactant has the most effect on changing the wettability to water wetness in comparison with anionic surfactant. Moreover, the recovery enhancement in the case of injection of alkaline–nonionic surfactant (67%) is more considerable than alkaline–anionic (65%).