Abstract:The Zhanhua Depression is a hydrocarbon-rich, fault-generated depression in Bohai Bay Basin, eastern China. Gubei slope zone, located in eastern Zhanhua Depression, is an important oil production region. Drilling cores, logging data, and 3D seismic data were used to identify several depositional system infilling the slope zone, including braided-delta, sublacustrine fans, and deep/ semi-deep lake fine-grained deposits and turbidite, all of which are associated with a lacustrine succession belonging to the 3rd … Show more
“…The lithology of the third member of the Shahejie Formation is gray or dark-gray mudstone interbedded with sandstone, shale, and limestone. The third member of the Shahejie Formation is the main hydrocarbon source intervals of the study area (Guo, 2016) and some sections with deeper burial depth in the third member of the Dongying Formation can also become favorable hydrocarbon source intervals (Figure 2). Figure 2.Strata integrated column of the Bohai Bay Basin, showing the lithology, sedimentary facies, tectonic evolution, and source–reservoir–caprock combination.…”
The Bohai Bay region is a primary accumulation area of oil and gas in offshore China, in which overpressure commonly occurs in the Paleogene strata; the analysis on distribution characteristics and genetic mechanisms of the overpressure would provide geologic evidences for making plans of well drilling and logging as well as oil and gas exploitation; additionally, it could lay the geological foundation for studying how overpressure controlled hydrocarbon accumulation. Based on research, the overpressure of the study area starts from the second member of the Dongying Formation and ends in the third member of the Shahejie Formation. The distribution of overpressure is mainly controlled by the sag-salient tectonic framework within the basin, which means overpressure mainly develops in sags or slopes; however, high areas stay normal pressured. In the study area, pressure develops around Bozhong Sag and in northern Liaodong Bay reaches the peak. The genetic mechanisms of overpressures in the Paleogene reservoirs are mainly disequilibrium compaction, hydrocarbon generation of the organic matter, fluid charging, and transmission or the superimposition of the former two. Different strata have different genetic mechanisms of overpressure. The chief genetic mechanisms for the generation of overpressure of the Dongying Formation are disequilibrium compaction while the genesis of the formation of overpressure in the Shahejie Formation is more complicated in some extent. The first member of the Shahejie Formation dominated by disequilibrium compaction and hydrocarbon generation of the organic matter plays a supplemental role, while the second member of the Shahejie Formation, as the primary reservoir strata, is dominated by fluid charging and transmission, and the third member of the Shahejie Formation is the main source rock interval; its overpressure is closely related to hydrocarbon generation. Each contribution ratio for overpressure forming by
“…The lithology of the third member of the Shahejie Formation is gray or dark-gray mudstone interbedded with sandstone, shale, and limestone. The third member of the Shahejie Formation is the main hydrocarbon source intervals of the study area (Guo, 2016) and some sections with deeper burial depth in the third member of the Dongying Formation can also become favorable hydrocarbon source intervals (Figure 2). Figure 2.Strata integrated column of the Bohai Bay Basin, showing the lithology, sedimentary facies, tectonic evolution, and source–reservoir–caprock combination.…”
The Bohai Bay region is a primary accumulation area of oil and gas in offshore China, in which overpressure commonly occurs in the Paleogene strata; the analysis on distribution characteristics and genetic mechanisms of the overpressure would provide geologic evidences for making plans of well drilling and logging as well as oil and gas exploitation; additionally, it could lay the geological foundation for studying how overpressure controlled hydrocarbon accumulation. Based on research, the overpressure of the study area starts from the second member of the Dongying Formation and ends in the third member of the Shahejie Formation. The distribution of overpressure is mainly controlled by the sag-salient tectonic framework within the basin, which means overpressure mainly develops in sags or slopes; however, high areas stay normal pressured. In the study area, pressure develops around Bozhong Sag and in northern Liaodong Bay reaches the peak. The genetic mechanisms of overpressures in the Paleogene reservoirs are mainly disequilibrium compaction, hydrocarbon generation of the organic matter, fluid charging, and transmission or the superimposition of the former two. Different strata have different genetic mechanisms of overpressure. The chief genetic mechanisms for the generation of overpressure of the Dongying Formation are disequilibrium compaction while the genesis of the formation of overpressure in the Shahejie Formation is more complicated in some extent. The first member of the Shahejie Formation dominated by disequilibrium compaction and hydrocarbon generation of the organic matter plays a supplemental role, while the second member of the Shahejie Formation, as the primary reservoir strata, is dominated by fluid charging and transmission, and the third member of the Shahejie Formation is the main source rock interval; its overpressure is closely related to hydrocarbon generation. Each contribution ratio for overpressure forming by
“…The Bohai Bay Basin is the largest oil and gas production basin among the petroliferous basins in China (Guo et al., 2016; Ma et al., 2016; Zhao et al., 2014). The study area is the Huanghua Depression, located in the north-centre of the Bohai Bay Basin, which overlies the Palaeozoic cratonic basin of North China; it developed as a fault basin in the Mesozoic and then as a rift basin in the Cenozoic.…”
The Huanghua Depression is located in the north-centre of Bohai Bay Basin, which is a rift basin developed in the Mesozoic over the basement of the Huabei Platform, China. Permo-Carboniferous source rocks were formed in the Huanghua Depression, which has experienced multiple complicated tectonic alterations with inhomogeneous uplift, deformation, buried depth and magma effect. As a result, the hydrocarbon generation evolution of Permo-Carboniferous source rocks was characterized by discontinuity and grading. On the basis of a detailed study on tectonic-burial history, the paper worked on the burial history, heating history and hydrocarbon generation history of Permo-Carboniferous source rocks in the Huanghua Depression combined with apatite fission track testing and fluid inclusion analyses using the EASY%R o numerical simulation. The results revealed that their maturity evolved in stages with multiple hydrocarbon generations. In this paper, we clarified the tectonic episode, the strength of hydrocarbon generation and the time-spatial distribution of hydrocarbon regeneration. Finally, an important conclusion was made that the hydrocarbon regeneration of Permo-Carboniferous source rocks occurred in the Late Cenozoic and the subordinate depressions were brought forward as advantage zones for the depth exploration of Permo-Carboniferous oil and gas in the middlenorthern part of the Huanghua Depression,
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