Application of sterane epimerization to evaluation of Yoshii gas and condensate reservoir, Niigata basin, Japan
- Shimane Univ., Nishikawatsu (Japan)
A practical method is used to assess maturation histories and paleotemperatures of mudstones. This method is based on 20R-C{sub 29} sterane epimerization and the apparent heating rate. A relationship among sterane epimerization, maximum burial temperature, and heating rate is determined assuming kinetic constants of sterane epimerization. This relationship is used to reconstruct the subsidence and thermal histories of mudstones and accumulated oils in the young Nishiyama/Chuo oil field (Tertiary-Quaternary). The estimated thickness of eroded sediments in the Haizume/Uonuma Formation, the uppermost rocks in the Nishiyama/Chuo oil field, indicate subsidence and heating rates of 2-4 km/m.y. and 80-160C/m.y., respectively, and uplift and cooling rates of 2-4 km/m.y. and 80-160C/m.y., respectively, during the late Quaternary. These rates suggest recent vigorous tectonism in the Niigata back-arc sedimentary basin. Based on geologic observations and maturation levels of crude oils, the oil generation threshold and primary migration stage correspond to degrees of sterane epimerization of 20S/(20S + 20R) = 0.20 to 0.35 and 20S/(20S + 20R) = 0.40 to 0.50, respectively. The anticlinal structure of Yoshi gas and condensate reservoir was formed prior to the late Pliocene. The thermal and subsidence histories of source rocks indicate that the accumulation of hydrocarbons in Yoshii reservoir rocks started in the Pleistocene. Further maturation of these reservoir rocks and the possible addition of gases from overmature source rocks during the late Quaternary resulted in formation of the Yoshii gas-condensate reservoir. Formation of anticlinal structure of Nishiyama reservoir began in the late Quaternary after the major stage of oil migration. Vigorous tectonism during the late Quaternary caused abrupt development of the anticline, allowing oil to accumulate to form Nishiyama reservoir.
- OSTI ID:
- 5846708
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 74:10; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
030200* -- Natural Gas-- Reserves
Geology
& Exploration
033000 -- Natural Gas-- Properties & Composition
ANTICLINES
ASIA
CENOZOIC ERA
CHEMISTRY
DEVELOPED COUNTRIES
ENERGY SOURCES
ENVIRONMENTAL TRANSPORT
FLUIDS
FOSSIL FUELS
FUEL GAS
FUELS
GAS FUELS
GASES
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOTHERMOMETRY
HYDROCARBONS
JAPAN
LIQUIDS
MASS TRANSFER
MATURATION
MINERAL RESOURCES
NATURAL GAS
NATURAL GAS DEPOSITS
NATURAL GAS LIQUIDS
ORGANIC COMPOUNDS
QUATERNARY PERIOD
RESERVOIR ROCK
RESOURCE ASSESSMENT
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
SOURCE ROCKS
TECTONICS
TERTIARY PERIOD