Enhanced Gas Recovery in Water-Drive Gas Reservoirs: Theoretical Advances, Engineering Practices, and Future Trends

Abstract

Water invasion is a core factor constraining efficient development and ultimate recovery in water-drive gas reservoirs. Non-uniform water invasion can reduce recovery by 15%-50% compared with water-free gas reservoirs of the same type. In recent years, the full-life-cycle enhanced gas recovery (EGR) philosophy, staged-technology framework, and integrated drainage-injection co-regulation models have continued to evolve, shifting water-drive gas reservoir development from passive water control toward proactive regulation, and from single-technology interventions toward multi-technology synergy. This paper systematically reviews the mechanisms of water blocking, water sealing, pressure-field imbalance, and relative permeability hysteresis, and their compound amplification effects across four scales. On this basis, it organizes primary, secondary, and tertiary gas recovery into a unified framework, and conducts a comparative analysis of key technologies including optimized regulation for water invasion prevention, intensive water drainage, N2/CO2 injection for energy replenishment, drainage-injection co-regulation, chemical water shutoff, and nano-fluid water-unblocking, along with their field application cases (Kela 2, Keshen 8, Keshen 24, Sebei, Dabei 102). The paper proposes four future breakthrough directions—AI and digital twin integration, cross-generation technology fusion, CCUS-EGR integrated deployment, and expansion toward extreme reservoir conditions—and advocates a paradigm shift in water-drive gas reservoir development from empirical staged treatment to intelligent, full-life-cycle adaptive EGR systems.