Abstract:  In order to comprehensively characterize the characteristics of reservoir space and pore-throat structure of the intra-platform reservoir of the Member 4 of Dengying Formation in the Gaomo area,  this study investigated the pore-throat structure characteristics of different types of reservoirs using physical property analysis, core and cast thin section observation, centrifugal NMR(nuclear magnetic resonance), and CT scans at different scales. The results show that the main storage spaces of the intra-platform reservoir are inter-crystalline (dissolved) pores and small solution cavities, with throats and fractures as the main flow channels. The rock density is low where fractures and cavities develop, and the dissolved fractures and cavities are distributed in clusters. The existence of fractures in fracture-cave type core can reduce the seepage resistance in the near-fracture area and increase the drainage efficiency of small-sized pores in centrifugal NMR experiments. Combined with the results of cast thin section and centrifugal NMR experiments, the cavity-type core was further classified into two categories: cavity gas storage and dissolved-pore gas storage. The dissolved-pore gas storage reservoir is difficult to develop but has high development potential. If reasonable reservoir improvement and surface operation measures are adopted, cavity-type core can serve as an important support for stable production in the middle and late stages of Intra-platform reservoir development.

Key words:  , intra-platform reservoir, pore throat structure, centrifugal NMR, drainage efficiency, storage and seepage feature, Dengying Formation