Laboratory Study of Silicate-Polymer Gel System for Water Shut-off in Hydrocarbon Reservoirs

Abstract

To reduce water production from oil and gas reservoirs, it is necessary to block certain fractures and layers of hydrocarbon formations. Although polymer gels are employed as water shut-off agents to reduce water production, they face challenges due to inefficiencies. This study aims to examine silicate-polymer gels, based on the factors influencing the formation of gel by focusing on controlling the gelation time of the silicate-polymer gelants at various temperatures and investigating the stability of gels. An experimental design was conducted based on 5 levels and 2 parameters, where these two parameters are the concentration of the polymer ranging from 0.06% to 0.3% by weight and the temperature ranging from 20 to 100 degrees Celsius in the presence of a crude oil from the southwest of Iran. Experimental results indicated that citric acid successfully covered the ions and effectively controlled the gelation time. Sodium silicate proved to be one of the main components, along with formation water, citric acid to mitigate the impact of formation ions on the gelation time, and the polymer itself. The presence of formation water led to an increase in gel strength and a decrease in the gelation time. Moreover, elevated temperatures resulted in shorter gelation times and lower viscosity in the polymer gel. Doubling the concentration of the polymer reduced the gelation time by 43%, while a two-fold increase in temperature decreased it by 54%. Increasing the concentration of the polymer indicated a decrease in the gelation time, and an increase in both gel strength and gel viscosity.