Geochemical effects of primary migration of petroleum in Kimmeridge source rocks from Brae field area, North Sea. I: Gross composition of C sub 15+ -soluble organic matter and molecular composition of C sub 15+ -saturated hydrocarbons

Journal Article · Tue Mar 01 00:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90331-6· OSTI ID:5237025

Leythaeuser, D; Schaefer, R G; Radke, M ^[1]

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1. Nuclear Research Centre (KFA), Juelich (West Germany)

In mature, oil-prone source rocks of the Upper Jurassic Kimmeridge Clay in the Brae field area, North Sea, the yield and the gross composition of solvent-extractable petroleum-like compounds, as well as the molecular proportions of C{sub 15+}-saturated hydrocarbons, are primarily controlled by the effects of hydrocarbon expulsion during primary migration. Within sample series extending from shale centers towards adjacent reservoir sandstones, regular and pronounced yield decreases have been documented, as well as marked compositional changes for C{sub 15+}-soluble organic matter and its compound class fractions and for normal and isoprenoid alkanes. Relative migration losses indicating relative expulsion efficiencies were determined for the C{sub 15+}-alkanes. Throughout the outer five meters of thick shales relative expulsion efficiencies increase regularly and drastically for all compounds considered, e.g. exceeding 90% for the C{sub 15+}-n-alkanes in the outermost shale samples. Samples from thin (5-50 cm) shale layers interbedded between reservoir sandstones reveal similarly high expulsion efficiencies. A simple conceptual model is proposed to explain the mechanisms and relationships of generation and expulsion processes in time and space. A geochemically-relevant conclusion is that the C{sub 15+}-soluble organic matter recovered by solvent extraction of mature source rocks represents only a portion of the total non-volatile petroleum-like material originally generated.

• OSTI ID: 5237025
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:3; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
NORTH SEA
OIL FIELDS
CHEMICAL COMPOSITION
SOURCE ROCKS
PETROLEUM
MIGRATION
CHEMICAL REACTIONS
GEOCHEMISTRY
HYDROCARBONS
JURASSIC PERIOD
MOLECULAR STRUCTURE
ATLANTIC OCEAN
CHEMISTRY
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MESOZOIC ERA
MINERAL RESOURCES
ORGANIC COMPOUNDS
PETROLEUM DEPOSITS
RESOURCES
SEAS
SURFACE WATERS
023000* - Petroleum- Properties & Composition
580000 - Geosciences