Recent Advances and Future Strategies in Chemical Water Shutoff for Gas Reservoirs Under Harsh Conditions

Water invasion has become a critical challenge during the late-stage development of gas reservoirs, particularly under harsh conditions characterized by high temperature, high salinity, and strong reservoir heterogeneity. Chemical water shutoff technologies have thus gained increasing attention as effective solutions for selectively restricting water production while preserving gas deliverability. This review systematically summarizes recent advances in chemical water shutoff for gas reservoirs, focusing on polymer gels, nanocomposite materials, relative permeability modification agents, and emerging functional fluids. The reviewed materials are analyzed in terms of dominant sealing mechanisms, gas-water selectivity, reservoir adaptability, and performance under extreme formation conditions. By critically comparing their advantages, limitations, and field applicability, key challenges related to deep placement, selective sealing, long-term stability, and engineering controllability are identified. To address these limitations, emerging concepts such as zonal synergistic water control and bioinspired gas-water barriers are discussed, integrating wettability regulation, multiscale sealing, and adaptive material responses. These strategies provide a conceptual framework and research direction for the design of next-generation, efficient, and sustainable chemical water shutoff systems in complex gas reservoirs.