Double-Chain Single-Head modification of extracted saponin from Anabasis Setifera plant and its effects on chemical enhanced oil recovery process by surfactant-alkali slug injection into carbonate oil reservoirs

Recently, several studies have dealt with the use of plant-derived surfactants in chemical water injection into oil reservoirs as a main method of Enhanced Oil Recovery (EOR). Some of the advantages of using them in comparison with using expensive chemical surfactants are being environmentally friendly, cheap and available. There are plenty of plants that could be employed as sources of natural surfactants owing to the saponin in their tissues. Even though the plants extracts have weaker performances than engineered surfactants in reducing Interfacial Tension (IFT), synthesizing and modifying the structure of the saponin of these plants can increase its surface activity and result in the optimal values of EOR parameters. The current work was conducted to modify the structure of the saponin of Anabasis Setifera plant through esterification as Double-Chain Single-Head. Thermal Gravimetric Analysis (TGA), Proton Nuclear Magnetic Resonance (H-1 NMR), and Fourier-Transform Infrared Spectroscopy (FTIR) were performed for temperature stability analysis and characterization. Surface tension experiments were performed in order to estimate the Critical Micelle Concentration (CMC) of the modified surfactant. Additionally, to prove the surfactant performance in EOR process, we did IFT and oil drop Contact Angle (CA) tests, evaluation of the salinity effects of Formation Water (FW), and various salts on IFT, CA, and flooding with optimum fluid in a carbonate plug. The results indicate low-IFT creation at CMC, carbonate rock wettability alteration to moderate wettability, and an increase in the oil recovery factor of about 19% in surfactant-alkali slug injection at optimal alkali and salinity conditions.