CHARACTERISTICS OF CA' ONIFEROUS MARINE CA ONATE RESERVOIRS IN EASTERN MARGIN OF PRECASPIAN BASIN

The Precaspian Basin is a supergiant petroliferous basin around the world. A series of large-scale carbonate oil fields are developed in its eastern margin. In this paper, the characteristics of marine facies carbonate reservoirs in the Precaspian Basin are studied based on core observation and thin section analysis, combined with logging curve, high-pressure mercury injection, physical property analysis, and various test data. According to the macroscopic and microscopic lithologic characteristics from the coring well, the lithology in the study area is divided into six types: granular dolomite, crystal grain dolomite, other dolomites, granular limestone, crystal grain limestone, and other limestones. Three types of reservoir space pores, vugs, and fractures are developed. They include structural fractures, interlayer fractures, pressolutional fractures, and corroded fractures, greatly affecting reservoir properties. The diagenetic facies here can be divided into 4 types and 7 subtypes by sedimentary background, rock type combination, main diagenesis, diagenetic evolution, and pore association type. Diagenetic facies analysis for simple wells is implemented, and then the spatial distribution of the reservoirs is analyzed. As a result, this study provides a reference for the searching of high-quality reservoirs.