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

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

The characterization and enhanced oil recovery mechanisms of a nanosized polymeric cross-linked gel are presented herein. A negatively charged nanogel was synthesized using a typical free radical suspension polymerization process by employing 2-acrylamido 2-methyl propane sulfonic acid monomer. The synthesized nanogel showed a narrow size distribution with one peak pointing to a predominant homogeneous droplet size. The charged nanogels 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. In addition, a fixed concentration of negatively charged surfactant (sodium dodecyl sulfate or SDS) was combined with different concentrations of the nanogel. The effect of the nanogels combined with surfactant on sandstone core plugs was examined by running a series of core flooding experiments using multiple flow patterns. The results show that combining nanogel and SDS was able to reduce the interfacial tension to a value of 6 Nm/m. The core flooding experiments 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

The Synergistic Effects of Nanoparticle-Surfactant Nanofluids in EOR Applications

Enhanced oil recovery (EOR) techniques are receiving substantial attention worldwide due to the major decline in the available oil resources. However, lots of challenges and limitations such as high costs, low sweep efficiency, and possible formation damage hinder the improvement of these EOR techniques. In addition, nanoparticles have proven to be potential solutions or improvements to a number of challenges associated with the traditional EOR techniques. Furthermore, surfactants are added to nanoparticle solutions to enhance their stability. In general, surfactant-coated nanoparticles are functionalized nanoparticles that consist of a nanoscale part with their surface active groups to perform specific tasks such as adsorbing at the oil-water interface to modify some of their properties including wettability and interfacial tension (IFT). The relative concentration ratio between surfactants and nanoparticles defines the properties of the modified surfactant-coated nanoparticles. If the concentration ratio between surfactants and nanoparticles is low, only a small portion of the nanoparticles would be coated with surfactants. Conversely, large concentration ratios mean that surfactants can form a double layer on the particle\u27s surface. The interactions between surfactants and nanoparticles can lead to a considerable change in the surface activity of surfactants. Multiple layers of surfactant-nanoparticle can be formed by the strong attraction between surfactant and nanoparticle molecules. Generally, surfactants with higher concentrations, which are entitled with a higher adsorption into the surface, can greatly reduce the interfacial tension (IFT) and alter the wettability towards a water-wet condition. The aim of this paper is to conduct a review of the recent literature on nano-technology and determine the most reliable mechanisms associated with different particles. The paper mainly focuses on the development and usage of nanoparticles in combination with surfactants to improve and enhance oil recovery. Different tests and experimental studies are presented to better understand the recovery mechanisms of the combination. The first part of this paper focuses on the recovery mechanisms of different types of nanoparticles. Next, the recovery mechanisms of surfactant-nanoparticle solutions are presented along with different experimental studies. Finally, the possible limitations and challenges that face the combination of surfactants and nanoparticles in EOR applications are presented

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

The aim of this study is to examine the effect of a novel combination that consists of polymeric nanogeland surfactant on oil recovery. The paper will report the extent to what the nanogel, alone and combinedwith surfactant, can improve oil recovery for sandstone reservoirs and reveal the mechanisms behind it. Anegatively charged nanogel was synthesized using a typical free radical suspension polymerization processby employing 2-acrylamido-2-methyl propane sulfonic acid monomer. In addition, a fixed concentration ofnegatively charged surfactant (sodium dodecyl sulfate or SDS) was combined with different concentrationsof the nanogel using seawater. The combination effect on sandstone core plugs was examined by runninga series of core flooding experiments using multiple flow schemes. The synthesized nanogels showed anarrow size distribution with one peak pointing to a predominant homogeneous droplet size. They were alsoable 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 ofthe nanogel, both alone and combined with SDS, to improve the oil recovery by a factor of 15% after initialseawater flooding. Although nanoparticles have received a great attention in the research aspect of the oilindustry, 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 potentialfor application in the oil industry. This study is aimed to examine and evaluate the combination of chargedpolymeric nanogel and surfactant dispersed in seawater through core flooding experiments using multipleinjection schemes