Experimental evaluation on the mobilization ratio of reservoir space in water-flooding gas storage

As the water moves back and forth during the high-speed injection and production of water-fooding gas storage, the geologic conditions and water fowing characteristics of reservoirs for gas storage building have more effect on the mobilization ratio of reservoir space in the gas storage. In this paper, saturation feld and nuclear magnetic resonance were analyzed in the cyclic injection-production simulation based on the reservoir characteristics of typical water-fooding gas storages at home. The injection-production parameters of multiple programs were comparatively analyzed by combining the physical simulation results with the numerical simulation results, and then converted into the feld index according to the similarity criteria. It is indicated that in the process of multi-cycle injection and production of water-fooding gas storages, some reservoir space is not mobilized. It is shown from 3D saturation feld and nuclear magnetic characteristic spectrum that the pure gas zone of gas displacement is the principal zone to increase the space mobilization and gas-water transitional zone is the main zone to worsen the space mobilization result of gas storage. The displacement based capacity expansion and the water-gas interlocking are in close relation with the injection-production rate of gas storage and the physical property zoning of reservoir space. As for the multi-cycle injection and production of typical water-fooding gas storages in North China, 26% storage capacity at the gas injection rate of 291×10⁴m³/d and gas production rate of 533×10⁴m³/d is defned as inactive storage capacity. The research results can be used as the reference for the rebuilding and injection-production optimization of water-fooding gas storages.