秋田地域に分布する新第三系のケロジェンのカイネディック特性

その他

It has been generally accepted that kerogen is the source matter of petroleum. Since Tissot and Welte(1978) had first presented the mathematical model based on kinetic characteristics of typical kerogen types (I, II, and III) , efforts of quantitative basin modeling had directed to evaluate how much oil were generated from kerogen during geologic past. However, it seems that geochemical aspect of each sedimentary basin is characterized uniquely in relation to its sedimentary environment.
The authors have developed a new method in order to determine the kinetic parameters (Genetic Potential : Xo, Activation Energy : E, Frequency Factor : A) for kerogen degradation from Rock-Eval data.
The method has been applied to the Akita Neogene basin, Notheast Japan. The Neogene formations may be divided into two groups according to their geochemical characteristics. Following standard stratigraphy in the Akita basin, the Nishikurosawa and Onnagawa Formations have the higher initial potential of petroleum than that of the Funakawa and Tentokuji Formations. It is suggested that the characteristics differs depending on the preservation of source materials affected by the sedimentary environments, such as the presence of Oxigen Minimum Layer with relation to the basin configuration and ventilation of sea water.
The method proposed here should be utilized to increase an accuracy in the quantitative evaluation of hydrocarbon generation from source rocks. The geochemical information derived by this method could be also applied to the paleoenvironmental analysis in addition to the lithological and biostratigraphic informations.