Lignin as a potential additive for minimizing surfactant adsorption on clay minerals in different electrolyte concentration

Abstract

The use of surfactants in chemical enhanced oil recovery can recover more oil trapped in the reservoir. However, the loss of surfactant due to adsorption on porous media renders the process ineffective and economically unfeasible. In this study, the adsorption of sodium dodecyl sulfate (SDS) and 4-octylphenol polyethoxylated (TX-100) on different clay minerals (kaolinite, montmorillonite, illite and quartz) as a function of the surfactant concentration, pH and salinity has been investigated. Besides, the use of lignin alkali as a sacrificial agent to reduce adsorption of surfactants in the reservoir is proposed. Surfactant adsorption on the different minerals was determined using the surface tension technique and batch equilibrium adsorption process with lignin as sacrificial agent. The experiment was conducted at varying pH and electrolyte concentrations. Furthermore, oil displacement test was conducted in a sandpack to determine the amount of oil recovered by the surfactant before and after pre-flush with lignin alkaline. Experimental result reveals that SDS adsorbed more on kaolinite while, TX-100 on montmorillonite. The decrease in pH increased the adsorption of SDS on kaolinite and illite, meanwhile, the adsorption of TX-100 on montmorillonite increased significantly at low pH. The optimum salinity concentration for both surfactants was at 20,000ppm for all the minerals except for kaolinite which was at 30,000ppm. Lignin alkaline reduced the surfactant adsorption by 50% and 53.2% for SDS and TX-100 respectively. Oil displacement test with SDS and TX-100 surfactants after water flooding had additional recovery of 7.44% and 4.18% respectively while, after pre-flush the recovery increased by 2.2%.