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The Bohai Sea area, offshore of the Bohai Bay Basin, is one of the most petroliferous regions in China, with proven original oil in place of approximately 2.4 x 109 m³ (150.94 x 108 bbl) and proven original gas in place of over 5 x 1012 m³ (1.76x 1013 ft³). Cumulative oil production is over 50 million tons (3.5 x 108 bbl). In this study, using the limited data on source rock thickness, core samples, and Rock-Eval pyrolysis along with sedimentary facies analysis, source rock characteristics of different depositional settings were identified, and the thickness, richness, organic matter type, and thermal evolution of four sets of source rocks in the Bohai Sea area--the second member of Dongying Formation (E3d2), the third member of Dongying Formation (E3d3), the first and second members of Shahejie Formation (E2S1-2), and the third member of Shahejie Formation (E2s3)--were predicted and evaluated. Subsequently, the intensity and history of hydrocarbon expulsion for different sags was systematically compared and analyzed. The greatest thickness of the four sets of source rocks in the Bohai Sea area is 400-800 m (1300-2600 ft). The average richness of the organic matter of these source rocks is 1.74%-2.87%. The E2s3 set has the highest organic matter abundance; E2s1-2 has the lowest. The organic matter of these source rocks is mainly type I and type II, but their evolutions differ. The vitrinite reflectance of E3d2 is 0.5%-1.0%, that of E3d3 is 0.7%-1.25%, that of E2s1-2 is 0.75%-1.75%, and that of E2s3 is 0.75%-2.0%. The cumulative hydrocarbon expulsion of the four sets of rocks is 4.14 x 1010 t (2.90 x 1011 bbl). The E2S1-2 set has the greatest expulsion amount: 1.75 x 1010 t (1.22 x 1011 bbl). The peak stages of hydrocarbon expulsion of the four sets of source rocks were during Neogene Minghuazhen Formation (12.2-2.0 Ma) and Neogene Guantao Formation (16.6-12.0 Ma). The Bozhong sag expelled the most hydrocarbons, followed by the Liaozhong, Qikou, and Huanghekou sags. [ABSTRACT FROM AUTHOR]

The Liaohe (辽河) depression is an important part of the Bohai (渤海) Bay Basin, and the Bohai Bay Basin located in the center of lithospheric destruction and thinning in the eastern North China Craton. The North China lithospheric thinning activities have been verified from evidences of structural geology, petrology, geochemistry and geophysics, but there are still some controversies on their timing, mechanism and controlling factors. The sedimentary basin is a thin-bedded geologic unit with a limited distribution in the upper lithosphere, and its formation and evolution represent the shallow response of the deep geodynamic process. Therefore, its thermal evolution is closely related to the deep dynamic conditions. In this article, the Mesozoic-Cenozoic thermal history of the Liaohe depression is reconstructed using the vitrinite reflectance and apatite fission track data. Meanwhile 'thermal' lithospheric thicknesses in the Mesozoic and Cenozoic are calculated using the geothermic method on the basis of the above thermal history results. The results show that the Liaohe depression has under- peaks, 81 and 83 mW/m, respectively, corresponding to two strong rift movements. Accordingly, the depression has experienced two different levels of thinning processes in the Cretaceous and the Paleogene since the Mesozoic, and the 'thermal' lithospheric thicknesses were 60 and 50 km, respectively. This may reveal that the depression has experienced two large-scale destructions. The work may provide valuable geothermal evidence for initial revealing the time, process and stage of the lithospheric thinning in the Liaohe depression. [ABSTRACT FROM AUTHOR]

The proposed functional-element constraint hydrocarbon distribution model consists of four basic functional elements including regional cap rock (C), favorable sedimentary facies (D), interfacial potential (P) and source kitchen (S). The combination of the four functional elements controls the formation and distribution of stratigraphic reservoirs in a basin. Regions with spatial and temporal overlaps of the four functional elements are the favorable zones for stratigraphic reservoirs. The geometric mean of the frequency of the four functional elements could indicate the possible distribution of stratigraphic reservoirs in a target zone. This paper describes constraint functions of the four functional elements on the hydrocarbon accumulations and their quantitative characterization. The hydrocarbon distribution model based on functional elements can predict development of stratigraphic reservoirs using T-CDPS, and the possibility for reservoir formation is determined by the index, T cdps , in this paper. Based on the model, we have predicted seven areas of the Paleogene E d 3 in Nanpu Sag, which are favorable or moderately favorable for stratigraphic reservoir distribution. Among all the seven areas, five areas located in the Gaoshangpu structural belt, south of Laoyemiao structural belt and Nanpu I, II, V structural belt were favorable areas. Two moderately favorable areas were located in Nanpu III structural belt and Nanpu IV structural belt. [ABSTRACT FROM AUTHOR]