Water-oil interfacial tension (IFT) reduction and wettability alteration in surfactant flooding process using extracted saponin from Anabasis Setifera plant

Abstract

Surfactants are known as interfacial tension (IFT) reducer additives in enhanced oil recovery (EOR) process. The use of chemical surfactants has always been a challenge due to the high cost of materials and sometimes non-compliance with the environment. Hence, researchers are looking for alternative ways to make them cheap and affordable. Herbal extracts that combine some surfactants, such as saponins, are a new source for replacing with expensive chemical surfactants. In this study, Anabasis Setifera plant was used as a source of natural surfactant supply. Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1HNMR) and thermal gravimetric analysis (TGA) were performed to characterize and determine the temperature stability, as well as surface tension tests for estimating the critical micelle concentration (CMC) of saponin extracted from Anabasis Setifera. In addition, pendant drop water-oil IFT test, contact angle test, and flooding of surfactant solution at CMC and optimum salinity were performed to study the application of the natural surfactant in EOR process. The effects of NaCl, KCl, CaCl2, MgCl2, FeSO4, K2SO4, and NaHCO3 salts and formation water salinity were investigated at different concentrations on the IFT and contact angle. The results show that the surfactant is more effective than conventional plant extracts and in combination with chemical surfactants and an IFT value of 1.066 mN/m was obtained at CMC. The contact angle tests also show the capability of this surfactant to alter the wettability to a poor water-wetting (a contact angle of 56.5°). Ultimately, an oil recovery of 15.4% was obtained by flooding of the surfactant solution at CMC and optimum formation water salinity.