--> ABSTRACT: Geochemical Characterization And Thermal Maturation Modeling of Gaocan-1 Well in Bohai Basin, by Zhiwen Han; #90906(2001)

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Zhiwen Han1

(1) Humble Geochemical Services, Humble, TX

ABSTRACT: Geochemical Characterization And Thermal Maturation Modeling of Gaocan-1 Well in Bohai Basin

Gaocan-1 well is located in southwest Tanghai County, on the north coast of Bohai Bay, China. The well penetrates the Tertiary basin-filling sequences and ends in the Jurassic basement rocks. The burial, erosional, and thermal history was reconstructed based on the well and regional geological and geothermal data.

Twenty-three cutting samples representing the Paleogene Shahejie and Dongying Formations were analyzed. Microscopic examination indicates that the 23 samples are basically similar in kerogen composition, characterized by a predominance of amorphous organic matter and ubiquitous occurrence of small amounts of alginite. The measured vitrinite reflectance (Ro) values increase from 0.29 to 1.21% with increasing burial depth, which was utilized in the optimization of the maturation model. Pyrolysis-gas chromatography analysis shows that the pyrolysis products are mainly composed of normal alkane and alkene doublets up to C33, indicating an aliphatic nature of the amorphous-dominated kerogen.

Five of the 23 samples were selected for kerogen kinetics analysis, showing the activation energy distributions mainly in a range of 56 to 59 kcal/mole. As the sample maturity increases (Ro from 0.29 to 0.55%), the activation energies get more and more concentrated and slightly shift to higher values. When the measured kinetic data of the 5 samples are applied to the established maturation model, respectively, the timing and amount of hydrocarbon generation vary from sample to sample. For example, the timing of onset of hydrocarbon generation (assuming 10% conversion ratio) of the Lower Shahejie Formation varies from 10 to 25 Ma, suggesting that kerogen maturity affect the kinetic parameters and, thus, the output of hydrocarbon generation modeling.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado