Resumo

JIANG, Fujie et al. Identification and hydrocarbon expulsion history simulation of the effective source rocks in the Dongying Formation, Paleogene, Bohai Sea area, eastern China. Rev. mex. cienc. geol [online]. 2013, vol.30, n.2, pp.355-370. ISSN 2007-2902.

This paper discusses a new method for identification and simulation of the hydrocarbon expulsion history of Effective Source Rocks (ESR) in the Dongying Formation (Ed), Bohai sea area, Bohai Bay basin, eastern China. This new method enables us to reliably identify the distribution and quantitatively determine the hydrocarbon expulsion history of ESR in petroliferous basins. ESR are the material basis for hydrocarbon accumulation, having important implications for oil and gas exploration prospects. The Bohai Bay basin is one of the most petroliferous basins in China, with nearly one third of the total oil production of the country. However, insufficient research on the ESR in the Dongying Formation (Ed), Bohai sea area, Bohai Bay basin obstructs further exploration. In this paper, ESR of Ed are identified with the new "two-stage and three-step" method, and their planar distribution is predicted by combining well data with sedimentary facies, and structure distribution. On that basis, the hydrocarbon expulsion history of ESR in the 2^nd Member (E₃d₂) and 3^rd Member (E₃d₃) of Ed was systematically simulated by using the hydrocarbon generation potential method. The results show that the ESR of E₃d₂ are distributed in four sags of Bohai Sea area, while the ESR of E₃d₃ occur in seven sags. Hydrocarbon expulsion from the ESR of E₃d₂ began during the deposition period of the Minghuazhen Formation Nm) (12 Ma) with a hydrocarbon expulsion quantity of 42 x10⁸ t. The hydrocarbon expulsion centers were located in the Bozhong, Huanghekou, Qikou and Bodong sags. Hydrocarbon expulsion from the ESR of E₃d₃ began around 16.6 Ma ago (hydrocarbon expulsion quantity of 84x10⁸ t), and the hydrocarbon expulsion centers were located in the Bozhong, Qinnan, Huanghekou, Liaozhong, Nanpu and Qikou sags. In conclusion, the hydrocarbon expulsion centers of the ESR of E₃d are mainly located in Bozhong, Huanghekou, Qikou and Bodong sags, with late-stage hydrocarbon expulsion (16.6-2 Ma), which is advantageous to hydrocarbon accumulation and preservation. The uplifts and slope belts around the hydrocarbon expulsion centers would be favorable exploration targets.

Palavras-chave : effective source rocks (ESR); hydrocarbon expulsion threshold; Dongying Formation; Paleogene; Bohai Sea; Bohai Bay basin; China.

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