Diagenetic Facies Analysis and HighQuality Reservoir Prediction in the Southern Xibu Depression of the Bohaiwan Basin

Key words: 
• highquality reservoir /
• secondary porosity zone /
• diagenesis /
• diagenetic facies /
• diagenetic modeling /
• sedimentary microfacies /
• Xibu Depression /
• Bohaiwan Basin

Abstract: There exist three secondary porosity zones vertically in the Cenozoic reservoirs of the Southern Xibu Depression of the Bohaiwan Basin as revealed by the measured porosity data，thin sections，blue epoxy resinimpregnated thin sections and scanning electron microscopes. As a result，the highquality reservoirs are developed． Sedimentary microfacies and diageneses control the formations and occurrences of the highquality reservoirs， which are dominantly formed in the channel mouth bar， braided channel and channel bar deposits， located in the early diagenetic stage B～middle diagenetic stage A1〖KG*2〗and dissolution diagenetic facies． The diagenetic stages and diagenetic facies are predicted by modeling the paleotemperature， vitrinite reflectance， sterane isomerization rate and authigenic quartz concentration in space and time． The highquality reservoirs of the third middle member of Shahejie Formation are delineated by superposing the diagenetic facies map on the microfacies map． They are mainly in the middle part of the slop of the Southern Xibu Depression．