Diagenetic facies and reservoir porosity evaluation of deep high-quality clastic reservoirs: A case study of the Paleogene Shahejie Formation, Nanpu Sag, Bohai Bay Basin, China

Petrological analysis, thin-section observation and laboratory analysis data were selected to systematically study the physical diagenetic features of first member Paleogene Shahejie Formation (Es 1 ) in No. 3 structural belt Nanpu Sag, Bohai Bay Basin. The intensities different processes determined, evolution sequence was reconstructed, typical facies identified effects diageneses on reservoir quantitatively analyzed. results show that main intergranular fillings include authigenic-quartz, quartz secondary enlargement, clay minerals, carbonate cement matrix. pore types porosity, dissolution porosity microfractures. has experienced compaction, early cementation, late among which compaction is most important reducer. Compaction process involved reduction, accounting for about 24.4% loss porosity. clearly improved increasing by 2.7%. Five basis petrographic analyses, namely, (a) strongly compacted-weakly cemented-weakly dissolved facies; (b) weakly compacted-strongly (c) moderately compacted-moderately (d) cemented-moderately (e) cemented-strongly facies. According diagenesis intensity, model various quality predicted. changed with depth. best compacted–weakly cemented–strongly facies, have good sorting, contain a large amount feldspar soluble debris, are mainly developed part river channel. Our can provide reference subsequent exploration development deep petroleum systems.