Laboratory evaluation of novel nano composite gel for water shut-off

Abstract

When extracting oil and gas from underground reservoirs, fluids such as water, CO2, polymer solutions, and surfactant solutions are often injected to displace the hydrocarbon resources. However, the presence of high-permeable layers, channels, and fractures in the reservoirs can hinder the efficiency of the displacement processes. The displacing fluids tend to channel through these high-permeability features, leaving behind significant amounts of hydrocarbon in low-permeability zones, which remain unswept. Recent developments in nanocomposite hydrogels, such as PPGs, have shown promising results for water shutoff due to their thermal stability and deformability. In this study, a preformed particle gel with nano additive (NC-PPG) was developed through free radical polymerization of AM, AMPS, and nanoclay. Nanoclay nanoparticles were found to act as physical cross-linkers in the polymer network, leading to smaller pore sizes and slightly enhanced thermal stability. The addition of an appropriate amount of nanoclay nanoparticles significantly improved the swelling rate and mechanical properties of NC-PPG. The presented composition also showed good salt tolerance, as evidenced by its compatibility with highly saline formation water and the plugging rate and RRF of 0.25% NC-PPG solution, which were 94.3% and 17.6, respectively, in the sand-pack flowing experiment. These results suggest that NC-PPG has the potential to effectively plug the high permeability zones in mature reservoirs, making it a suitable candidate for water shutoff treatment and enhanced oil recovery (EOR) strategies. The ability of NC-PPG to improve sweep efficiency and control water flow in reservoirs can contribute to more efficient oil production and reservoir management practices. Keywords: enhanced oil recovery; water shut-off; plugging efficiency; preformed particle gel; nanoclay; sweep efficiency.