Multiple Medium Integrated Modeling Technology for Carbonate-Based Underground Gas Storage

There are lots of challenges for carbonate-based Underground Gas Storage (UGS) evaluation, among which the problem of heterogeneous reservoir modeling restricts the optimization of UGS. In this study, based on the static and dynamic data of seismic, geological and development, the matrix, bedding dissolution cave, vertical dissolution cave and fracture composite heterogeneous reservoirs in the target area are comprehensively characterized for the demand of UGS. The concept of reservoir-seepage system was proposed. The concrete method was to decompose the complex heterogeneous carbonate rock mass into Matrix-Cavity Pore Body (MCPB) and Fracture-Cavity Seepage Body(FCSB), and then use different scale data combined with reservoir simulation technology to characterize the MCPB and FCSB, so as to effectively simulate the complex heterogeneous carbonate reservoir-seepage system. Statically, the model is consistent with the results of geological conditions and seismic prediction, and can be used for the optimization of heterogeneous reservoirs. Dynamically, the numerical simulation of gas reservoir based on multiple medium model objectively reflects the seepage process along the fracture direction during production. This technology can effectively guide the overall evaluation of UGS and the scheme of injection-production wells.