Recent advances in polymer gels in oil and gas drilling and production engineering: A review

Polymer gels are recognized as essential functional materials in oil and gas drilling and production engineering due to the design flexibility of their three-dimensional networks, the controllability of their mechanical properties, and their high adaptability to extreme environments. They are extensively utilized for profile control, water shutoff, wellbore stabilization, treatment of severe lost circulation, and enhanced oil recovery. This paper systematically reviews the latest research progress on crosslinked and non-crosslinked polymer gels in the field of oil and gas drilling and production engineering, with a particular focus on their synthesis principles, interfacial interactions, and engineering applications. Regarding crosslinked polymer gels, this paper summarizes structural design strategies for pre-crosslinked, in-situ crosslinked, and composite systems, elucidating the pivotal role of multi-scale crosslinked networks in enhancing thermal stability, salt tolerance, and shear resistance. For non-crosslinked polymer gels, this paper discusses diverse reversible interaction mechanisms, including hydrophobic association, hydrogen bonding, electrostatic interactions, and supramolecular assembly. Furthermore, it highlights their distinct advantages in environmental responsiveness, self-healing behavior, and rheological modulation. Furthermore, this paper analyzes the microscopic interfacial processes of polymer gels within porous media and fractures from three perspectives, interfacial adhesion, interfacial rheology, and mechanical response. This analysis clarifies the crucial role of interfacial interactions in governing dynamic transport, anchoring, gelation, and long-term stability. In critical application areas such as lost circulation control and enhanced oil recovery, gel systems have evolved from conventional single-function plugging materials to advanced high-performance systems characterized by stimuli-responsiveness, intrinsic self-healing capabilities, and multifunctional synergistic effects. This paper outlines the developmental directions of polymer gels in drilling fluids and enhanced oil recovery. The synergistic optimization of rational molecular design, composite network construction, and interfacial modulation strategies holds the promise for overcoming the performance limitations of gel materials in harsh environments, such as high temperature and high salinity, thereby facilitating their large-scale deployment in deep and ultra-deep oil and gas development.