Hydrocarbon generation potential of the Cretaceous section from Well ALP-6, Perija Region, Venezuela

Conference · Mon Feb 01 04:00:00 EST 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5941457

Pratt, L ^[1]; Mompart, L; Murat, B ^[2]

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1. Indiana Univ., Bloomington, IN (United States)
2. Maraven S.A., Caracas (Venezuela)

Geochemistry and sedimentology have been integrated in order to provide a better understanding of the source rock potential and depositional environments of the La Luna Formation and Machiques Member in Well ALP-6 (Perija region). These two units, the dominant source rocks in the Maracaibo Basin, are mainly shales with high to very high organic content, while thin interbeds of limestones are poor in organic matter. A detailed sedimentological study and sequence analysis indicates that both shaly units represent a period of platform infilling subsequent to drowning. Periods of progressive back stepping culminating in the deposition of organic-rich condensed intervals are recognized, based on sedimentology of cores and wireline log analysis. A succession of fining-upward sequences, 1' to 5' thick, with distinct sedimentological and geochemical signatures have been identified in the La Luna Formation. Phenomena of early diagenesis (intrashale calcite growth due to organic matter degradation; sulfur precipitated in local paleolows) to late diagenesis (pressure-solution effects with development of laterally correlatable cone-in-cone layers) are all indicators that the hydrocarbon generation potential of La Luna is not uniform and can only be assessed by detailed geological, sedimentological and geochemical investigations. Two geochemically distinct facies can be identified in both La Luna and Machiques. A sulfur-rich facies is characterized by Corg/AVSul ratios averaging 1.9 and by exceptionally high concentrations of sulfur-bearing aromatic compounds. A sulfur-poor facies is characterized by Corg/AVSul ratios averaging 9.2 and by trace concentrations or absence of sulfur-bearing aromatic compounds.

• OSTI ID: 5941457
• Report Number(s): CONF-930306--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 77:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CALCITE
CARBONATE MINERALS
CHEMISTRY
CRETACEOUS PERIOD
DEPOSITION
DEVELOPING COUNTRIES
DIAGENESIS
ELEMENTS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
GROWTH
HYDROCARBONS
INDICATORS
LATIN AMERICA
LAYERS
MESOZOIC ERA
MINERALS
NONMETALS
ORGANIC COMPOUNDS
ORIGIN
PETROLEUM GEOLOGY
RESOURCE POTENTIAL
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEDIMENTATION
SEDIMENTS
SHALES
SOURCE ROCKS
SOUTH AMERICA
SULFUR
VENEZUELA