著者

加藤 進 西田 英毅 岩野 裕継

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.79, no.3, pp.171-179, 2014 (Released:2016-07-15)

参考文献数

29

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Three oil samples, eight gas samples, and three rock samples, collected mainly from surface seepages in the northern Fossa Magna region, Nagano Prefecture, Japan, were subjected to geochemical analysis, yielding the following results.1) The oils are heavy and biodegraded, and are classified as Kubiki-type (Hirai et al., 1995). Geochemical characteristics of the oils indicate an origin from type II-III organic matter, and their maturity is estimated to be ∼ 0.7% Ro equivalent.2) The gases are mainly methane (C1); only three samples from Tenjinzawa and Nakatsuka contain heavier hydrocarbons, up to C6, and these samples have with high wetness over 10%. The chemical and isotopic compositions of the gases indicate that they are partly biodegraded and mostly thermogenic in origin, with a maturity of 0.7%-0.9% Ro equivalent.3) Mudstones in the Bessho Formation and the lower part of the Aoki Formation are probably the source rocks that generated the oil and gas in the areas of the Takafu and Komeji synclines as indicated by source rock analysis and by surface oil and gas seepages. Although subsurface geologic structures remain unclear, there is hydrocarbon potential in the zone between the areas of oil and gas seepages and the synclines.

著者

島津 光夫 西田 英毅 小西 博巳 竹下 良美

出版者

一般社団法人 日本地質学会

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.120, no.7, pp.247-253, 2014-07-15 (Released:2014-11-12)

参考文献数

11

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Asphalt and asphaltite were found in the Yashiroda oil field where crude oil was produced between 1869 and 1925. This is a report on the first finding of asphaltite in Japan, covering the asphalt mass of heavy crude oil origin that flowed from a drilled well. The asphaltite specimen is black with brilliant luster and conchoidal fracture, and has a specific gravity of 1.17. X-ray diffraction analysis confirmed it as amorphous as evident from a broad peak at 2θ = 18°-25°. Biomarker analysis by GC-MS showed that the asphalt and asphaltite specimens are both of marine origin, the same as the crude oil bitumen collected from the Niitsu oil field. Many excavated asphalt remains at the Osawayachi ruins (Jomon-Heian to Kamakura periods) might have originated from the Yashiroda oil field, which is situated 600 m east of the excavation area.

著者

加藤 進 西田 英毅

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.75, no.4, pp.286-295, 2010 (Released:2012-03-01)

参考文献数

32

被引用文献数

3 2

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The methylphenanthrene distributions of crude oils from oil and gas fields have been measured in the JAPEX Research Center as a part of the routine geochemical analysis since 2004. We have examined the validity of the two methylphenanthrene maturity parameters, the methylphenanthrene index 1 (MPI 1) and the methylphenanthrene ratio (MPR), for crude oils in Niigata Prefecture (the Niigata oils). The results are summarized as follows.1) The Niigata oils show a regular change with maturity on the MPI 1-MPR plot.2) The Niigata oils are divided into the following three maturation stages on the MPI 1-MPR plot.Stage 1 : oil generation stageStage 2 : condensate generation stageStage 3 : oil cracking stage3) The MPI 1-MPR plot is applicable to crude oils in the Akita and Hokkaido districts.4) This plot is useful for the estimation of relative maturity levels and the oil to oil correlation.