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Previous HitCarbonateNext Hit Reservoir Within the Ordovician in the Dongpu Area, Bohai Bay Basin, Eastern China: Previous HitDiagenesisNext Hit and Diagenetic Evolution

Abstract

Abstract

The Previous HitcarbonateNext Hit reservoirs within the Ordovician in Dongpu area, Bohai Bay Basin are characterized by deep buried, complicated structural evolution history and variable Previous HitdiagenesisNext Hit. Recent years, the study interval has become a target of hydrocarbon exploration. However, its Previous HitdiagenesisNext Hit and diagenetic evolution are understudied. This study uses cores, thin sections, cathodoluminescence, SEM, fluid inclusions, associated with regional geology data to investigate the Previous HitdiagenesisNext Hit and diagenetic evolution of Previous HitcarbonateNext Hit reservoirs within the Ordovician in Dongpu area.

Our results reveal that micrite and dolomitic limestone, calcite dolomite and gypsiterous dolomite are the dominant rock types. The Previous HitdiagenesisNext Hit types and heir evolution history are cementation, compaction, penecontemporaneous dolomitisation, penecontemporaneous dissolution, supergene dissolution, structural fracturing, hydrothermal dissolution, pressure solution, burial dolomitization, recrystallization. The homogenization temperature of fluid inclusions shows that temperature changes are mainly distributed in five interval range: 185 ∼ 257°F, 257 ∼ 329°F, 329 ∼ 401°F, 401 ∼ 473°F, 473 ∼ 545°F. The five different fluid stage are correspond to the five types of Previous HitdiagenesisNext Hit environment: syngenetic Previous HitdiagenesisNext Hit stages, early atmospheric freshwater Previous HitdiagenesisNext Hit stages, early shallow buried Previous HitdiagenesisNext Hit stages, supergene freshwater dissolution stage, middle - deep buried Previous HitdiagenesisNext Hit stages. Cementation, compaction and penecontemporaneous dolomitization mainly occurred in the syngenetic Previous HitdiagenesisNext Hit stage, penecontemporaneous dissolution mainly developed in the early atmospheric freshwater Previous HitdiagenesisNext Hit stage, supergene dissolution developed in supergene freshwater dissolution stage, structural fracturing, hydrothermal dissolution, pressure solution, burial dolomitization and recrystallization developed in middle - deep buried Previous HitdiagenesisNext Hit stage.

Our study also suggests that the cementation, compaction and pressure solution are the dominated Previous HitdiagenesisNext Hit, which significantly damaged pores within reservoir, whereas penecontemporaneous dolomitisation, penecontemporaneous dissolution, supergene dissolution, structural fracturing, hydrothermal dissolution are the main Previous HitdiagenesisNext Hit which improved the porosity of reservoir. The development of the Previous HitcarbonateNext Hit reservoir within the Ordovician in Dongpu area is the result of the superposition of these Previous HitdiagenesisTop.