Experimental investigation on the injection profile variation in the weak gel injection process

Abstract

In this paper, the gel-forming performance and rheological properties of weak gel systems were studied through laboratory gel-forming experiments. The plugging behavior and mechanism of the weak gel system for sand-packed tubes with different permeability were evaluated. The results showed that intramolecular cross-linking was dominated when the polymer concentration was low and the viscosity increased litter after gelation. Intermolecular cross-linking plays a major role when the polymer concentration is high. The injection speed has a great influence on the resistant factor (RF in short) of the weak gel. During low-speed injection, the weak gel has a large amount of retention on the surface of the rock particles, resulting the high viscosity of the weak gel. The RF during low-speed injection is much higher than that in high-speed injection and it keeps increasing as the injection volume increase. The impact of the injection rate on RF of hydrolyzed polyacrylamide (HPAM) is significantly lower than weak gels, because the retention of HPAM in the sand-packed tube reaches a stable level, the RF remains basically unchanged.