Petrophysical facies characteristics and reservoir classification evaluation of the glutenite reservoir of the E₃d³ of Paleogene in the Block C, western Shijiutuo Uplift

Using core, cast thin sections, scanning electron microscopy, conventional physical properties and dynamic monitoring data, the petrophysical facies of the glutenite reservoir in the E₃d³ of the Block C of the Bohai Bay is studied under the comprehensive action of sedimentary facies, diagenetic facies and pore structure phase. The results show that fan-delta front subfacies are the main sedimentary microfacies of the E₃d³ in the study area, with four types of sedimentary microfacies: near-shore channel, detrital flow, far-shore channel and distributary bay. Diagenetic facies can be divided into mud/sandy mixed base filling phase, compacted dense phase, unstable component dissolution phase and carbonate cementation phase. The pore structure phase can be divided into large pore type, middle pore type, large pore type and small pore type. Reservoir Quality Index (RQI) value was selected to characterize the influence of different sedimentary facies, diagenetic facies and pore structure on the reservoir. By calculating the quantitative characterization parameter values of the reservoir petrophysical facies, the influence of different facies on the reservoir physical property and productivity was characterized. The petrophysical facies of the E₃d³ in the study area were divided into 3 categories, corresponding to class Ⅰ—Ⅲ reservoirs. Based on the output profile test data obtained in the early production period production well of the E₃d³ in the study area, the rationality of classifying reservoirs by the static parameters of petrophysical facies is verified. The research results can provide some geological basis for the next step of injection and production optimization and potential adjustment of well location selection in this area.