COMPARATIVE STUDY BETWEEN SODIUM PERSULFATE AND SODIUM HYPOCHLORITE BREAKERS FOR HYDROXYETHYL CELLULOSE AND XANTHAN POLYMERS
Sand production is undesirable during hydrocarbon production. Gravel pack is the most popular and most robust sand control technique. Slurry or viscous pack process enables large concentration of proppants to be transported to the wellbore. Hydroxyethyl cellulose and xanthan gums possess some qualities that make them to be the most popular polymers used to formulate viscous gravel carrier fluid. The viscous gravel pack fluid must be degraded after depositing the proppant to facilitate hydrocarbon production without impairment. Various types of gel breakers are available for effective polymer degradation. The choice of the type of breaker employed depends on wellbore conditions and the type of fluid system. The rate of polymer degradation is a function of many factors including the type and concentration of breaker. In this paper, the action of sodium persulfates and sodium hypochlorite oxidizer breakers on the degradation of hydroxyethyl cellulose and xanthan based polymer fluids at various temperatures was evaluated. Sodium persulfate was effective in degrading 40 and 60 lbs/1000gal hydroxyethyl cellulose and xanthan fluids at temperatures above 140oF and 160oF respectively but the breaker was ineffective below these temperatures. Sodium hypochlorite effectively degraded both polymer fluids at 120oF. Therefore, sodium hypochlorite oxidizer breaker can be used for low temperature applications where sodium persulfate is not effective without using breaker activator.