| Budget Amount *help |
¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000)
Fiscal Year 2014: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2012: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Outline of Final Research Achievements |
Concentration and compositional changes of hydrocarbon gases in shale rocks and metapelites during diagenesis and metamorphism were revealed by this study. The shale rocks and metapelites were collected from borehole MITI-Mishima and outcrops in Shimanto belt, Chichibu belt, and Sanbagawa metamorphic belt in Shikoku region. Concentration of residual methane begins to increase when shale rock porosity reaches about 5%, suggesting a significant retention of methane in shale rocks. The highest concentration of residual methane corresponds to maturity levels of vitrinite refrectance (VR)=2 to 3 % (maximum heated temperature=200 to 250ºC). Residual methane concentration significantly decreases in the stage of metamorphism suggesting the graphitization of methane. The maturity level of VR=2 to 3 % is the main maturation stage for the formation of shale gas deposit. Several gas seepages observed in Shimanto belt suggest the formation of shale gas deposits in accretionary prism.
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