Polymer Gel Systems for Water Management in High-Temperature Petroleum Reservoirs: A Chemical Review

Polymer gel systems as water management materials have been widely used in recent years for enhanced oil recovery applications. However, most polymer gel systems are limited in their ability to withstand the harsh environments of high temperature and high salinity. Those polymer gel systems that can handle high-temperature excessive water treatments are reviewed in this paper and categorized into three major types: in situ cross-linked polymer gels, preformed gels, and foamed gels. Future directions for the development of polymer gel systems for high-temperature conditions are recommended. For excessive water management with temperatures from 80 to 120 degrees C, current polymer systems are substantially adequate. Polymer gel systems composed of partially hydrolyzed polyacrylamide (HPAM)/chromium can be combined with nanoparticle technology to elongate their gelation time and reduce the adsorption of chromium ions in the formation. Phenolic resin cross-linker systems have reasonable gelation times and gel strengths; however, more environmentally friendly cross-linkers should be developed to meet the increasingly stringent environmental requirements. For particle gels, the addition of functional monomer(s) can improve the antitemperature performance. When the applied temperatures reach 120 degrees C, inorganic cross-linker systems are no longer applicable, and the gelation time of organic cross-linking polymer gel systems and gel thermal stability will decrease significantly due to fast cross-linking reactions. During this period, retarders can be used to elongate the gelation time, and gel strength enhancers (e.g., cement, silica) can also be applied to improve the gel strength at such extremely high temperatures. Most importantly, novel polymers (e.g., ter- or tetrapolymers), functional monomers, and environmentally friendly cross-linkers need to be discovered and developed for polymer gel applications. Second cross-linking systems can be applied to further enhance the strength of the particle gels in harsh conditions. On the basis of these developments, foamed gels can be well implemented in fractures and wormholes to save the amount of injected gels.