PETROPHYSICAL CHARACTERISTICS AND RESERVOIR PREDICTION OF SHALE GAS IN CHANGNING BLOCK SICHUAN BASIN

The Sichuan Basin and its periphery are rich in shale gas resources. Among them, the Longmaxi Formation in the Changning block develops marine deposits, which is a favorable facies belt for the development of high-quality reservoirs. Because shale mineral composition and the abundance of organic matter determine the characteristics of the reservoir and the amount of oil and gas resources, it is necessary to analyze the rock composition and physical characteristics of the shale reservoir to find the relationships between the petrophysical parameters, mineral composition, and abundance of organic matter to evaluate shale gas reservoirs. In this paper, the Longmaxi Formation shale in the Changning block is used as the research object. By using microscopic thin slices, cast thin slices, X-ray diffraction and other methods, we carry out shale penological characteristics and reservoir physical properties. Studies have shown that the target layer is dominated by quartz and clay minerals. The inorganic pores, organic pores and fractures are the three main types of storage space in Longmaxi Formation reservoirs. Inorganic pores include intergranular pores, intragranular pores, and intercrystalline pores. The organic dissolved pores are formed with the evolution of organic matter and are round and elliptical. There are two types of cracks. According to the analysis of rock physical parameters, organic carbon content is negatively correlated with density and wave impedance, and positively correlated with gas content. Among them, organic carbon content has the highest correlation with density parameters. Through the analysis of reservoir and petrophysical characteristics, the classification standard for high-quality shale reservoirs has been established, which provides theoretical support for shale gas enrichment areas.