High accuracy analysis of new gas deposits from Cretaceous and Paleogene in Hokkaido on the basis of fluid inclusion and application to mining developments.

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K05358
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Fukuoka University
• Principal Investigator: Aizawa Jun 福岡大学, 理学部, 助教 (70184249)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 新規ガス鉱床 / 北海道 / 白亜系 / 古第三系 / 流体包有物

Outline of Final Research Achievements

The purpose of this research is to estimate underdeveloped fuel deposits in Hokkaido, northeast Japan on the basis of paleotemperature from authigenic minerals that coexist with carbonaceous matter. Combined analysis both inorganic mineral and organic carbonaceous matter is useful not only to clarify past temperature under diagenetic condition but also to construct actual thermal history of sedimentary basins that closely related to generation of methane as well as petroleum. In addition to selected localities and horizons around the district, samples were collected from underground mining areas, borehole cores and cuttings. Obtained data indicate from ca 75 to 100℃, however, no stratigraphic increase with burial depth is observed. This indicates that organic maturation proceeds later stage of burial diagenesis with short duration. As most of carbon in host sedimentary rocks up to 10 wt% is not inorganic, appropriate thermal history as above may generate new fuel deposits.

Free Research Field

石炭地質学

Academic Significance and Societal Importance of the Research Achievements

当地域では夾炭古第三系に伴うメタンガスが炭鉱の坑内で、古第三系の下位にくる白亜系露頭では石油の兆候が知られていたが、1960年代以降は陸上調査・研究が無いまま今に至る。本研究で質量%の桁の炭素（殆どが有機態炭素）を含む堆積岩試料を地表・坑内・ボーリング現場から得て、このうち堆積物が岩石化する過程で新たに生じた鉱物（自生鉱物）を検討した結果、岩石がおかれた温度は約75ー100℃、鉱物中の流体包有物は有機物の分解過程で生じたメタンを含む事例もあることが判った。白亜系や古第三系に加え、ガス・石油の後からの移動次第では先白亜系と新第三系にも新たな燃料資源鉱床が存在する可能性が高いことが明らかになった。