Recovery Factor of Pure Helium Injection in Depleted Gas Reservoirs and Its Influencing Factors

ABSTRACT As a non‐renewable and strategically scarce resource, helium requires underground storage facilities to ensure national supply security. To address the lack of systematic research on pure helium storage behavior and recovery factors in depleted gas reservoirs, this study employs reservoir numerical simulation to investigate the effects of injection rate, production rate, storage duration, and injection‐production schemes on helium recovery. The simulation incorporates helium's high diffusion characteristics and reservoir stress‐sensitivity effects, with model validation through history matching. Targeting a storage capacity of 15 million m 3 of high‐purity helium, the study systematically analyzes the controlling factors affecting pure helium recovery efficiency. The results indicate that helium recovery factor in depleted gas reservoirs is jointly controlled by injection‐production parameters and storage cycles. The competitive mechanism between diffusion loss and pressure maintenance dominates the evolution of recovery factor: short‐cycle operations (immediate production) achieve the highest recovery factor of 88.64%, medium‐term cycles (1–2 years) maintain recovery factors of 83%–84%, while recovery stabilizes after 3 years of storage (83.13%–83.23%). Specifically: (1) Synergistic control of low injection rates and high production rates can effectively enhance recovery factors. (2) Storage duration is a critical factor affecting recovery, with longer storage periods resulting in greater diffusion losses; the evolution exhibits a three‐stage characteristic of “rapid decline‐gradual decline‐stabilization.” (3) Under continuous multi‐year injection schemes, recovery factors demonstrate a “rapid decline‐gradual decline‐stabilization” trend, with the dynamic equilibrium between diffusion losses and pressure replenishment stabilizing recovery at 81%–82%. This study provides theoretical foundations and parameter optimization strategies for the construction and operation of strategic helium storage facilities in depleted gas reservoirs.