Application of Nanoparticles in Chemical EOR

Abstract

Summary More than 50% of origin oil in place are still trapped in reservoir after primary and secondary oil recovery. Thus, there is a need in tertiary recovery or enhancing oil recovery (EOR) methods, which include chemical flooding, steam injections etc. It is well known that chemical flooding is one of the most perspective and widely used method for enhancing oil recover. However, chemical species such as surfactants or polymers are very sensitive to high temperature, salinity and pH. Indeed, injecting alkaline solutions into wellbore aid in increase of brine solution salinity and pH, that may cause polymer destruction. This fact makes their use in oil recovery difficult. Replacing an alkaline solution with nanoparticles is a promising way of getting more stable surfactant and polymer solutions in typical reservoir conditions. In the present work, we investigated the influence of adding nanoparticles to surfactant solutions for improving their properties. Due to amphiphilic properties, surfactants are using as lowering interfacial tension (IFT) agents between brine solution and oil. The problem with surfactants injection is the high adsorption of surfactant molecules on the rock surface. Usually, to avoid high adsorption, alkaline solutions are added, but in sandstone formations alkali may cause polymer destruction and in carbonate formations - precipitation of several unfavorable inorganic scales. First, in this work, was shown that the addition of a low nanoparticles concentration to anionic (sodium alpha-olefine sulfonate) and cationic (erucyl bis(hydroxyethyl)methylammonium chloride) surfactants results in the decrease of IFT between solutions and oil. Then, the adsorption measurements were performed on brine solutions in a presents of different nanoparticles concentrations. The amount of adsorbed surfactants molecules decreases upon addition of nanoparticles, which is due to hydrophobic interaction between nanoparticles and molecules parts. Such reduction is almost the same with alkaline solution injection. However, a higher concertation of alkali is necessary to prevent a high adsorption on rock surface. Thus, the addition of nanoparticles to surfactant solutions retains their responsibilities to reduce IFT and, in addition, decreases adsorbed amount of surfactant molecules. As a result, less surfactant and polymer will be needed to reach low IFT and high viscosity of brine solution.