DEPOSITIONAL AND RESERVOIR CHARACTERISTICS OF THE CRETACEOUS CHISHAN FORMATION IN SUBEI BASIN AND THEIR SIGNIFICANCE

Based on the oil drillings and field geological outcrop,combined with the regional geologic data, and using thin section analysis, porosity and permeability data and mercury injection experiments analysis, a systematic study has been done about the characteristics of depositional and reservoir petrological character,pore character and physical property character. The results show that, as the most important subfacies of desert, aeolian deposit is the significant feature. The dune is composed of large sediment thickness with high mature and conspicuous electrical property. The formation of the pores are mainly affected by the dissolution with few primary pores, however, the secondary pores are abundant and form excellent reservoir for oil and gas. The study of dune has important practical significance for the exploration and development of petroleum.