Programmed pyrolysis of organic matter from thermally altered Cretaceous black shales

Journal Article · Tue Nov 01 04:00:00 EST 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6289425

Peters, K E; Hunt, J M; Tarafa, M E; Whelan, J K

Organic-rich Cretaceous black shales from the Cape Verde Rise in the eastern Atlantic were penetrated by hot diabase sills during the Miocene. Programmed pyrolysis and pyrolysis-gas chromatography of organic matter from core samples taken at various distances from a major sill were used to show: the type of kerogen, its relative level of thermal maturity, the fraction of pyrolyzable organic compounds which are free, and the compositions of the bitumen and kerogen. The dominant factor affecting these sediments appears to be thermal maturity rather than differences in the quality of the organic matter. Systematic changes in the pyrolyzate resulted from thermal cracking of volatile organics from the oil-prone Type II kerogen. Generation of these products caused progressive aromatization of the residual kerogen closer to the sill. These conclusions are supported by changes in kerogen elemental compositions, quantity of bitumen extract, and vitrinite reflectance. Although the major sill is 15 m (about 50 ft) thick, solvent extraction and pyrolysis results show that hydrocarbon generation was restricted to within about 10 m (about 33 ft) of the shale/sill contacts. At equal distances, the maximum temperature reached by the shales was higher above than below the sill. The reflectance of vitrinite responds more rapidly than bitumen composition to high temperatures imposed over a short time.

• Research Organization: Chevron Oil Field Research, La Habra, CA
• OSTI ID: 6289425
• Journal Information: Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:11; ISSN AAPGB
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040201* -- Oil Shales & Tar Sands-- Site Geology-- (-1989)
AROMATIZATION
ATLANTIC OCEAN
BITUMENS
BITUMINOUS MATERIALS
BLACK SHALES
CARBONACEOUS MATERIALS
CENOZOIC ERA
CHATTANOOGA FORMATION
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHROMATOGRAPHY
CRETACEOUS PERIOD
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
GAS CHROMATOGRAPHY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
KEROGEN
MATERIALS
MATTER
MATURATION
MESOZOIC ERA
MINERAL RESOURCES
OIL SHALE DEPOSITS
OIL SHALES
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC MATTER
OTHER ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
PYROLYSIS
REFLECTIVITY
RESOURCES
SEAS
SEPARATION PROCESSES
SURFACE PROPERTIES
SURFACE WATERS
TAR
TERTIARY PERIOD
THERMOCHEMICAL PROCESSES
VOLATILE MATTER