Development of highly stable lamella using polyelectrolyte complex nanoparticles: An environmentally friendly scCO_2 foam injection method for CO_2 utilization using EOR

摘要

CO2 foam flooding is a proven technology that enhances oil recovery and geological storage by improving the mobility of the injected CO2 in depleted reservoirs. Surfactant drainage, disintegration and rock adsorption have long affected the stability of CO2 foams in saline formations. To generate a more stable foam front in the presence of crude oil and to overcome the capillary forces destabilizing the foam lamella, polyelectrolyte complex nanoparticles (PECNP) conjugated with surfactant oligomers are introduced to the lamella generated by an aqueous phase containing high salinity to improve the EOR performance and produced water compatibility of supercritical CO2 (scCO(2)) foams. The formation of vesicular structures containing electrostatically hinged complexes of PECNP and surfactant was verified via transmission electron microscopy (TEM) while the structural changes associated with molecular complexation were identified using Raman spectroscopy. Accordingly, optimized ratios of PECNP:surfactant were employed to generate the most stable scCO(2) foam in high salinity produced water and improve the recovery of the foam flooding process. The effect of PECNP-conjugated surfactant on stability, durability, and interfacial properties of scCO(2) foam were examined. A set of core-flooding experiments in a wide range of salinity proved the capability of scCO(2) foam systems enhanced using PECNP-surfactant to offer the highest apparent viscosity and incremental oil recovery. A variety of injection scenarios tested on oil-saturated limestone core samples indicating that the highest incremental oil recovery and the lowest residual oil saturation are achieved by prioritizing PECNP:surfactatnt scCO(2) foam flood in optimized electrolyte concentrations.