Thermal maturity and kerogen type of Miocene sands, offshore Vermilion Parish, Louisiana
Representative lithofacies of the Miocene (Burdigalian) Robulus L zone from the Texaco 6 well, Vermilion Block 31, offshore Louisiana, were sampled and subjected to mean vitrinite reflectance measurements and programmed pyrolysis. Vitrinite reflectance and pyrolysis T/sub max/ results are consistent; they indicate organic matter in the Robulus L sands is thermally immature to marginally mature with respect to oil generation. Based on low hydrogen indices (HI) and high oxygen indices (OI) measured during pyrolysis, kerogen in the Robulus L interval is type III with no meaningful oil source potential. Maceral analysis supports this assertion. Crude oil in these reservoirs has migrated from deeper and more mature source rocks. Total organic carbon in the interval ranges from 0.26% in the sand lithofacies to 0.99% in the interbedded sand and shale lithofacies. Because of the predominance of recycled organic matter in the coarse size fractions, finer size fractions (< 10 ..mu..m) had significantly lower T/sub max/ values than the coarse fraction (> 10 ..mu..m) and whole-rock samples. The presence of type III kerogen at a pregenerative stage of maturity suggests this reservoir interval is a possible source of carboxylic acids. The carbonate dissolution observed in the robulus L sands may have been caused by this organic acid production. Hence, organic matter deposited in association with reservoir facies may be important in porosity modification and should be considered in studies concerned with geochemical mass balances.
- Research Organization:
- Louisiana State Univ., Baton Rouge (USA)
- OSTI ID:
- 6127635
- Report Number(s):
- CONF-8810362-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 72:9; Conference: Gulf Coast Association of the Geological Society and Gulf Coast Section of SEPM meeting, New Orleans, LA, USA, 19 Oct 1988
- Country of Publication:
- United States
- Language:
- English
Similar Records
Sterane and triterpane biomarker characteristics from oils and sediment extracts of the Middle-Late Miocene sequences, Northern Sabah Basin, Malaysia
Sedimentology and characteristics of dispersed organic matter in Tertiary Niger delta: origin of source rocks in a deltaic environment
Related Subjects
LOUISIANA
PETROLEUM DEPOSITS
SOURCE ROCKS
MATURATION
KEROGEN
MIOCENE EPOCH
OPTICAL PROPERTIES
PYROLYSIS
SANDSTONES
VITRINITE
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CENOZOIC ERA
CHEMICAL REACTIONS
DECOMPOSITION
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MACERALS
MATERIALS
MINERAL RESOURCES
NORTH AMERICA
ORGANIC MATTER
PHYSICAL PROPERTIES
RESOURCES
ROCKS
SEDIMENTARY ROCKS
TERTIARY PERIOD
THERMOCHEMICAL PROCESSES
USA
020200* - Petroleum- Reserves
Geology
& Exploration