Potential Oil Recovery Enhancement by a Polymeric Nanogel Combined with Surfactant for Sandstone Reservoirs

Abstract

The aim of this study is to examine the effect of a novel combination that consists of polymeric nanogel and surfactant on oil recovery. The paper will report the extent to what the nanogel, alone and combined with surfactant, can improve oil recovery for sandstone reservoirs and reveal the mechanisms behind it. A negatively charged nanogel was synthesized using a typical free radical suspension polymerization process by employing 2-acrylamido-2-methyl propane sulfonic acid monomer. In addition, a fixed concentration of negatively charged surfactant (sodium dodecyl sulfate or SDS) was combined with different concentrations of the nanogel using seawater. The combination effect on sandstone core plugs was examined by running a series of core flooding experiments using multiple flow schemes. The synthesized nanogels showed a narrow size distribution with one peak pointing to a predominant homogeneous droplet size. They were also able to adsorb at the oil-water interfaces to reduce interfacial tension and stabilize oil-in-water emulsions, which ultimately improved the recovered oil from hydrocarbon reservoirs. The results suggest the ability of the nanogel, both alone and combined with SDS, to improve the oil recovery by a factor of 15% after initial seawater flooding. Although nanoparticles have received a great attention in the research aspect of the oil industry, however, the characterization of polymeric nanogels, alone and combined with other additives, is still to be investigated. Due to their unique properties and mechanisms, nanogels have a great potential for application in the oil industry. This study is aimed to examine and evaluate the combination of charged polymeric nanogel and surfactant dispersed in seawater through core flooding experiments using multiple injection schemes.