Abstract: Based on the analytical data of cored wells, such aspetrographic thin section, cast thin section, scanning electron microscope, poroperm characteristics, capillary pressure curves and clay components, and in combination with logging interpretations of reservoir poroperm characteristics, the H1 - N21 reservoirs in Gaskuier oilfield are comprehensively studied in respects of rock characteristics, diagenesis, pore structure, poroperm characteristics and heterogeneities. It is believed that the reservoirs have medium porosity and medium permeability, which are mainly influenced by sedimentary facies and diagenesis, strong intraformational and areal heterogeneity, and weak inter-formational heterogeneity. Measures should be taken to prevent rapid fingering of edge water through highly permeable zones during production, which might influence recovery factor of oil.