(36f) Development of Novel Zwitterionic Surfactants for Enhanced Oil Recovery Under Harsh Conditions

Chemical-based Enhanced Oil Recovery (EOR) techniques employ surfactants to facilitate the recovery of residual oil trapped after primary and secondary production phases. However, the effectiveness of these surfactants is mostly hampered by challenges such as poor solubility in oilfield water and instability in reservoir conditions with high salinity and temperature. This study aims to evaluate the feasibility of utilizing indigenously synthesized surfactants, designed specifically for EOR processes, under such challenging reservoir conditions. Moreover, investigates the effect of varying hydrophobic tail and hydrophilic head groups on the physicochemical properties of the surfactants.

Novel surfactants were designed and synthesized using environmentally sustainable solvents or solvent-free methods. Incorporating an amide group [NHC=O] into the structure of surfactants offers distinct advantages over the surfactants lacking this group including low toxicity and remarkable biodegradability. The chemical structures were confirmed using NMR (¹H, ¹³C) and FTIR spectroscopy. The other parameters such as thermal gravimetric analysis, critical micelle concentration, adsorption, and IFT were also measured.

These newly synthesized surfactants demonstrated excellent solubility in both high and low-salinity water without experiencing precipitation, phase separation, or cloudiness. Surfactants produced in-house demonstrated outstanding physicochemical properties such as low cmc, low IFT, and less adsorption onto the reservoir rocks. Particularly noteworthy was the decomposition temperatures which were greater than 300°C, surpassing the average reservoir temperature.

These unique features underscore the significant potential of these surfactants for application in carbonate reservoirs characterized by high temperatures and salinity.