Challenges of Gel Treatment Application for Conformance Control
Abstract
This article explores challenges in gel treatments, including polymer dissolution, gelation time, gel strength, stability, resistance to brine flow, and permeability damage in oil reservoirs. It highlights strategies to enhance gel performance, such as optimizing the polymer/crosslinker ratio to reduce syneresis due to limited mixing time and using chromium chloride for rapid gelation at low temperatures. As for large gel treatments, 1-day gelation can be achieved with high molecular weight gels (~20-30 million Da) using 0.05wt.% chromium acetate at 25°C, although they exhibit reduced stability at higher temperatures. For high-temperature conditions, 500,000 Da gels are recommended at a minimum concentration of 2.5wt.%, with cold water pre-flush as an effective gelation delay method. Core flooding tests demonstrate that 500,000 Da gels can maintain efficacy under challenging conditions, achieving post-flush pressure gradients comparable to those provided by 0.5wt.% high molecular weight gels in more favorable scenarios. Permeability damage remains a significant issue, as evidenced by 0.5wt.% polymer gel reducing sand pack oil permeability by 340 times, with no significant recovery through NaOH treatment. Developing effective formulations to restore oil permeability after unsuccessful treatments could enhance confidence in using gels, potentially reducing water cut and minimizing oil production losses.