Surfactant Adsorption and Ion Exchange on Calcite Surfaces

Surfactant adsorption and ion exchange on calcite surfaces are investigated by means of flooding experiments in Estaillades limestone cores. We show that, in the 5000 mg/L salinity range, effluent concentrations can be captured in a reactive transport model that includes calcite dissolution, ion exchange, complexation of divalent ions, and the monomer–micelle equilibrium. In this model, ion exchange and adsorption are described by the screening of the negative surface charge by cations and surfactant–divalent ion complexes. We further show that adsorption can be reduced by a factor of 10 by coinjection of surfactant and polyacrylate or a polyacrylate preflush, which is attributed to a combination of divalent ion complexation and adsorption to the rock surface.