Reducing adsorption of anionic surfactant for enhanced oil recovery: Part II. Applied aspects

Abstract

The surfactant loss due to adsorption has significant economic consequences for surfactant-based enhanced oil recovery (EOR) processes. Alkali, traditionally used as sacrificial agent to reduce adsorption of anionic surfactants, cannot be efficiently used in the presence of anhydrite due to the reactivity of carbonate with anhydrite. In our previous publication, the competitive adsorption mechanism of an anionic surfactant and polyacrylate has been studied. In this work, the effect of some reservoir parameters on application of polyacrylate as a sacrificial agent is investigated. Addition of polyacrylate is shown to reduce adsorption of different anionic surfactants on different outcrop minerals, including Carlpool dolomite, industrial calcite, kaolinite, Berea sandstone, and Indiana limestone. The effect of salinity, concentration of Ca2+ ions, and temperature on effectiveness of sodium polyacrylate as sacrificial agent has been evaluated on different minerals/rocks. Results of dynamic adsorption measurements with sodium polyacrylate are also reported. Cost analysis shows that addition of a small amount of polyacrylate can significantly decrease the total material cost to as low as one-fifth of that without use of sacrificial agent. The reduction in cost depends on the values of dimensionless numbers developed in this paper. Altogether, these experiments demonstrate the advantage of using sodium polyacrylate as sacrificial adsorption agent for anionic surfactants even in the presence of anhydrite in the reservoir.