Breaking the Triple “Skeleton–Liquid Loading–Liquid Lock” Barrier: Research Progress and Integrated Prospects for Surfactants for Repairing Deep Natural Gas Reservoirs

Deep natural gas reservoirs are characterized by high temperatures, high pressure, high salinity, high condensate oil, and low permeability. Deep gas reservoirs frequently experience damage due to solid-skeleton destabilization, wellbore liquid loading and microscopic capillary liquid lock. These damages may occur independently or together under reservoir conditions. These damage modes may cooccur or interact in some deep gas reservoirs, and such scenarios can make single-function surfactant remediation insufficient. This review focuses on three functional classes of surfactants—clay stabilizers, foaming agents, and liquid-lock release agents—that target these three damage stages. Recent advances in molecular design, formulation optimization, and performance evaluation are summarized. Anionic, cationic, amphoteric, nonionic, as well as fluorocarbon-based surfactants whose headgroups may be ionic or nonionic each show distinct merits under given test conditions, yet most existing systems still experience limited salt/oil tolerance, weak adsorption stability, insufficient wettability reversal, and poor compatibility under extreme reservoir conditions. More importantly, current studies have largely focused on individual agents, while integrated remediation strategies that simultaneously stabilize the solid framework, enhance macroscopic liquid flow, and release microscopic capillary liquids are immature. Key bottlenecks include insufficient targeting in molecular design, unclear synergistic mechanisms, limited dynamic evaluation methods, and conflicts between environmental sustainability and cost. We propose that future research should prioritize obtaining a mechanistic understanding of interfacial synergies, static–dynamic coupled evaluation, and green low-cost synthesis, thereby accelerating the development of integrated reservoir repair agents for efficient and stable deep natural gas production.