Experimental study on a novel EOR method -- polymeric nanogel combined with surfactant and low salinity water flooding to enhance oil recovery

“Extracting higher amounts of oil from current reservoirs is a necessity for the oil industry to enhance their profitability and sustainability. The desire to recover more oil from the existing reservoirs has led to a growing interest of nanoparticle application in enhanced oil recovery (EOR). However, most researchers have focused on the evaluation and surface modification of non-deformable nanoparticles. This dissertation evaluates the potential of deformable nanogel particles as an EOR material when they are combined with two other promising technologies - surfactant and low salinity water floodings. The particle size distribution, ζ-potential and interfacial tension were measured for a newly developed nanogel when dispersed in brine with different salinities. The core flooding experiments, using sandstone and carbonate rocks, have indicated the ability of nanogelsurfactant flooding to emulsify crude oil in-situ and produce it as oil-in-water emulsion. The results have also revealed that substantial oil recovery, up to 27%, beyond conventional seawater flooding can be obtained by nanogel combined with SDS injections and assisted with altering salinity and ionic content of post water injections. Surfactant injection has shown to reduce nanogel adsorption density on rock surfaces. The injectivity and plugging performance induced by nanogel injection through sandstone and carbonate reservoir rocks were elucidated to assess their potential as oil recovery improvement agents. Emulsification is believed to be a major recovery mechanism of nanogel-assisted surfactant flooding. Here, oil-in-water Pickering emulsions stabilized by nanogel and surfactants using different brine salinities, pH, homogenizing time were evaluated for the formulation of a stable oil droplets. The confocal microscopy images have shown that stable oil-in-water Pickering emulsions are formed by nanogel combined with anionic surfactant and low brine salinity. The results presented in this dissertation promote the effect of nanogel assisted-surfactant flooding combined with low salinity water as a promising method for enhancing oil recovery”--Abstract, page iv