Heavy oil removal using modified polyacrylamide and SDS

Abstract

Composite systems of surfactants have been extensively applied in the recovery and removal of heavy oil. In this work, the characteristics and mechanisms of heavy oil removal in surfactant-polymer systems (SP) were investigated. The effects of the main factors, including the oil-to-water ratio, washing temperature, washing time, and shear rate, on the oil washing rate (OWR) were analyzed through the response surface methodology (RSM). The results demonstrated the ratio of oil to water had the most significant impact on the OWR compared to other factors. Based on the experimental data and the analysis of variances, a high-precision model was established, and the predicted OWR value was 42.0 % at the formation temperature (50 °C). In addition, the adsorption process of the SP molecules onto quartz silica was well represented by the pseudo-second-order kinetic model and the Freundlich isotherm. This indicates that the SP system has the characteristics of multilayer rebinding and heterogeneous adsorption. On the other hand, the adsorption thermodynamics identified that the adsorption was endothermic and unspontaneous. The dynamic experiments showed that the removal of heavy oil was clean and efficient without secondary adsorption and contamination on the solid surface. Furthermore, the oil removal of the SP system was determined by the mechanism of wettability alteration, utilizing the adsorption of SP molecules onto the solid surface to displace the adsorbed heavy oil molecules. The findings enhance the understanding of heavy oil removal by the surfactant-polymer composite system, which is frequently overlooked in conventional methodologies.