石油根源岩に関する反応熱力学的研究(第1報)Kerogenの低温熱分解実験に伴うbitumenの生成

抄録

It has been generally accepted that kerogen is the source material of petroleum. The authors have performed experiments of isothermal pyrolysis as one of fundamental studies for the kinetic evaluation of petroleum souce rocks. Samples are the kerogen isolated from mudstone of the Onnagawa Formation in Oga Peninsula, Akita Prefecture, and Recent sea tangles. These samples and N₂ gas are sealed in Pyrex tube, and pyrolised at 220°-300°C. The thermal decomposition of these samples are accompanied with the generation of bitumen, and oil is considered to be formed through intermediate formation of bitumen. The authors made a rection model based on the assumption that the generation of bitumen can be represented by the combination of several 1st-order reactions which occur independently and in parallel. This reaction model is compared with the experimental data, and then the results are as follows:
1) Only a part of kerogen takes part in the formation of bitumen (Fig. 1, Table 2, 3).
2) The generation process of bitumen is not a simple 1st-order reaction but is approximated by the above-mentioned reaction model (Fig. 2, 3, 4, 7, 8).
3) Characteristics of the decomposition of kerogen and/or generation of bitumen are represented in the forms of frequency distribution of kerogen that consists of several types of chemical bonds (Table 2, 3).
4) The proportion of chemical bonds represented by low activation energy in the building-block of Recent sea tangle is larger than that of Tertiary kerogen (Table 2, 3).
5) The main part of kerogen seems to show high energy level as the maturation of kerogen.