Anionic Surfactant Adsorption through Porous Media in Carbonate Cores: An Experimental Study

Abstract

The phenomenon of surfactant adsorption at solid/liquid interface is of major importance in the process of enhanced oil recovery. The basic objective of this study is to calculate adsorption density and also to model the kinetics of adsorption processes on carbonate rocks. The kinetics adsorption was calculated by examining adsorption behavior in a system of a solid phase (carbonate rock) and an aqueous phase of surfactant with 5,000 ppm synthetic/field brine. The surfactant adsorption on reservoir carbonate rocks was measured to determine the amount of excess surfactant that must be added into the injection stream in the surfactant alternating CO2 injection tests. The adsorption densities were measured by using circulation tests through core samples. The range of initial surfactant concentrations were 500, 1,000, 2,000, and 5,000 ppm in a circulating system. The applied commercial surfactant is sodium lauryl sulphate, which is an anionic surfactant. Finally, the Langmuir adsorption isotherm was used to characterize the equilibria between the amount of adsorbate that accumulates on the adsorbent and the concentration of the dissolved adsorbate. The adsorption process showed that the rate of adsorption is dependent on availability of surfactant in the system. It was found that the adsorption of surfactant increased with increasing surfactant concentration. Also, for the flow-through tests, the necessary equilibrium time was approximately 4 days.