Dongying Sag Paleogene Into The Rock Sequence Distribution Of High Quality Reservoir

This paper is focused on the application of sequence stratigraphy and diagenetic stratigraphy on the basis of research findings of reservoir diagenesis in the Dongying depression. With the establishment of organic and inorganic geochemistry indexes which indicate the original sedimentary environment, we can analyze the original water medium conditions and water-rock interactions in sequence stratigraphic framework, then to study the characteristics of early diagenesis in different system tracts and different sedimentary environments, and then to discuss the dominate influence of early diagenesis to middle-late diagenesis. With this principle, the paper discussed the distribution of high-quality reservoir in Dongying depression.Based on formers' data, six long-term base-level cycles (third-order sequence) are distinguished from Paleogene in Dongying depression, and four long-term base-level cycles are focused on in the 2nd and 3rd member of the Shahejie Formation, and sedimentary facies structure and distribution characteristics of sedimentary systems are summarized.Under the different sedimentary environments of studied sections, diagenesis characters of clastic rocks primary compositions, carbonate cementation and clay minerals are analyzed, and evaluation standard and indexes of paleo-salinity, Eh value and PH value of original water medium are established in the studied sections in the target areas, and diagenetic environment and evolution characters of diagenetic environments in second-order sequence are analyzed.Finally, taking the southern gentle slope in Dongying depression as an example, the characteristics of diagenesis in different system tracts in the sequence stratigraphic framework based on diagenetic sequence are studied. It concludes that submarine fans develop in low system tracts, beach bar in expanding system tracts, and delta in high system tracts. It also discusses the control of early diagenesis environments and the influence of middle-late diagenesis by water medium conditions in different system tracts and different sedimentary environments during the processes of sequence stratigraphic development.Based on the discussion above, evaluation standard of different genetic kinds reservoirs are established in Dongying depression. Distribution pattern of high-quality reservoir is summarized, which provides an important geological basis for the prediction of high-quality reservoir distribution.