Investigation of loss of surfactants during enhanced oil recovery applications - adsorption of surfactants onto clay materials

Abstract

Chemical flooding, or surfactant flooding, is a well known EOR technique which has been used worldwide for decades. For this method to be economically feasible, it is crucial to minimize the loss of surfactant to the reservoir. Currently the industry is considering combining chemical flooding with the newer technique of low salinity waterflooding which also has proved to be an efficient method for increasing oil recovery from reservoirs. In this study the adsorption of the anionic surfactant Aerosol OT onto kaolinite has been investigated by the indirect method of measuring surface tension.The adsorption studies were conducted under four different salinities, categorized by ionic strength and ionic composition. The experiments were performed with and without calcium to study the effect of ionic composition. The ionic strength of the solutions were 0,6 and 0,2. The results reveal that adsorption of Aerosol OT does occur onto kaolinite, and that reducing the ionic strength of the solution also reduces adsorption. The presence of divalent cations was found to promote adsorption. The method which was utilized for this study was considered to have limited accuracy and thus more experiments would be preferred to confirm the results. The tendencies of adsorption are however in agreement with the theories of similar studies and should be considered to be valid.