著者

加藤 進

出版者

石油技術協会

雑誌

石油技術協会誌 (ISSN:03709868)

巻号頁・発行日

vol.53, no.2, pp.131-143, 1988 (Released:2008-03-27)

参考文献数

36

被引用文献数

1 2

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Several hydrocarbon deposits have been found in volcanic rocks of the Nanatani stage (so-called Green Tuff) in the Niigata basin, Japan.Their characteristics are summarized as follows.1) Hydrocarbon deposits are formed in anticlinal structures and are mostly located close to depressions.2) Oil accumulations have been found in anticlinal structures which are formed in the early stage.3) All hydrocarbon deposits except for the Shiunji gas field are located in the Chuetsu sub-basin.4) Larger oil and gas fields are located in or close to the kitchen areas of oil and gas. This suggests the short lateral migration of hydrocarbons together with the distribution of oil and gas in neighboring areas of the Mitsuke oil field.5) In larger gas fields, the Teradomari formation shows a typical abnormally high pressur e, whereas the Geen Tuff is hydrostatical or slightly highly-pressured. On the other hand, formation pressure in the Mitsuke oil field increases toward lower straigraphic horizons that is similar to the pressure distribution in the Shiiya and Nishiyama reservoirs. These pressure patters are closely related to the manner of accumulation of oil and gas.6) The migration of oil and gas in larger oil and gas fields is thought to have occurred during and after the Nishiyama stage.7) The distributions of oil and gas in the Green Tuff depend rather on the kinetics of hydrocarbon expulsion from source rocks than on the type of organic matter. The kinetics of expulsion is controlled by the relative positions of the hydrocarbon generation zone and the overpressured zone.The Niigata basin can be sub-divided into three parts according to their geologic conditions: Kaetsu sub-basin, Kakuta-Sanjo uplift and Chuetsu sub-basin. Considering the combination of trap, source rock, reservoir and migration mechanism, it is concluded that the Chuetsu sub-basin is the most prospective for future exploration.