Effects of nanoparticles, polymer and accelerator concentrations, and salinity on gelation behavior of polymer gel systems for water shut-off jobs in oil reservoirs

Abstract

Excess water production is one of the crucial complications in the oil industry, leading to a rapid decline in oil production. To overcome this problem, different polymer gels are used to block the water's path to reduce water production. In the present work, polymer gel systems were prepared with polymers namely partially hydrolyzed polyacrylamide (PHPA), organic crosslinkers like hexamine, and hydroquinone with the incorporation of silica and alumina nanoparticles. Nanoparticles are used to enhance the stability of the gel framework in high salinity and high temperature reservoir environment. When designing the polymer gel system, factors such as pH, thermal stability, brine composition, injection rate, and chemical concentration were considered. Concentrations of PHPA and nanoparticles were varied from 1 to 2 wt% and 0.25–1.0 wt% respectively for the preparation of different gel systems. The concentration of the organic crosslinker was extended from 5000 to 11000 ppm for investigating the effect on gelation time. Brine concentration was chosen from 2 to 8 wt% to find the impact of high salinity. Succinic acid as an accelerator was also used to study the effect on gelation time, and it was found that the gelation time is reduced as the concentration of succinic acid increases. The prepared polymer solution was taken in a test tube and was kept inside a hot air oven at 95 °C to perceive the gelation time and nature of the produced gel. Results showed that nanoparticles do not influence the gelation time, but they considerably affect gel stability. However, concentrations of polymer, accelerator, and salt (salinity) have significant effects on the gelation behavior of the gel systems.