Thermal maturation and organic richness of potential petroleum source rocks in Proterozoic Rice Formation, North American Mid-Continent rift system, northeastern Kansas
- Kansas Geological Survey, Lawrence, KS (United States)
- Geological Survey, Denver, CO (United States)
A recent well in northeastern Kansas penetrated 296 ft (90.2 m) of dark gray siltstone in the Precambrian Mid-Continent rift (Proterozoic Rice Formation). Correlations indicate this unit may be as thick as 600 ft (183 m) and is possibly time-equivalent to the Nonesuch Shale (Middle Proterozoic) in the Lake Superior region. The upper half of this unit qualifies as a lean source rock (averaging 0.66 wt.% TOC), and organic matter in it is in the transition stage between oil and wet gas generation. The presence of the gray siltstone in this well and similar lithologies in other wells is encouraging because it indicates the source rock deposition may be common along the Mid-Continent rift, and that parts of the rift may remain thermally within the oil and gas window. Microscopic examination of calcite veins penetrating the dark gray siltstone reveals numerous oil-filled and subordinate aqueous fluid inclusions. Homogenization temperatures indicate these rocks have been subjected to temperature of at least 110-115[degrees]C (230-239[degrees]F). Burial during the Phanerozoic is inadequate to account for the homogenization temperatures and thermal maturity of the Precambrian rocks. With the present geothermal gradient, at least 8250 ft (2.5 km) of burial is necessary, but lesser burial may be likely with probably higher geothermal gradients during rifting. Fluorescence colors and gas chromatograms indicate compositions of oils in the fluid inclusions vary. However, oils in the fluid inclusions are markedly dissimilar to the nearest oils produced from Paleozoic rocks.
- OSTI ID:
- 5465920
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:11; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
Similar Records
Thermal history of the 1.1-Ga Nonesuch Formation, North American mid-continent rift, White Pine, Michigan
Proterozoic Midcontinent Rift System, an overview
Related Subjects
KANSAS
PETROLEUM DEPOSITS
EXPLORATION
RESERVOIR ROCK
GEOTHERMAL GRADIENTS
LITHOLOGY
PETROLEUM GEOLOGY
PRECAMBRIAN ERA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
MINERAL RESOURCES
NORTH AMERICA
PETROLOGY
RESOURCES
TEMPERATURE GRADIENTS
USA
020500* - Petroleum- Products & By-Products