Misoa formation sandstone diagenesis, blocks III and V, Maracaibo Basin, Venezuela

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

OSTI ID:5939473

Manske, C M ^[1]

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1. OMNI Laboratories Inc., Houston, TX (United States)

The petroliferous Lower-Middle Eocene Misoa Formation of the central Maracaibo Basin, Venezuela, is considered an ideal rock unit for investigation of controls on reservoir diagenesis. The Misoa Formation of the central Basin is typically a fine to medium grained, moderately to well sorted sandstone, with shale interbeds, representing deposition in various delta front to shallow marine environments. Sandstones are mainly sublitharenites and quartzarenites. The diagenetic evolution of the Misoa Formation in Blocks III and V of the central Basin area has been established through quantitative basin modeling, and detailed petrographic analysis involving thin section study, scanning electron microscopy, and X-ray diffraction analysis. The reservoir sandstones have been substantially modified by diagenesis. Porosity enhancement has been created in these rocks through the dissolution of unstable framework grains and carbonate cements. A major control on dissolution may be organic acid flushing prior to hydrocarbon generation; a mechanism supported by quantitative basin modeling results. A second control on porosity enhancement and reservoir quality is extensive leaching by meteoric waters near the post-Eocene unconformity surface. Sandstones nearer this surface have excellent porosity and permeability, and display profuse leaching of grains, clays, carbonate cements, and even quartz. Although Misoa sediments were affected by basin-wide tectonism including initial Eocene subsidence, an extended period of post-Eocene uplift and erosion and Miocene subsidence, the paragenetic sequence appears uniform. This diagenetic scenario reflects early burial diagenesis, telediagenesis, and medium to late burial diagenesis stages. Authigenic minerals include various carbonate, silica, and clay phases. The clay mineral assemblage in this area is represented by common kaolinite, with subordinate discrete illite, and ordered mixed-layer and expandable mixed-layer illite/smectite, chlorite.

• OSTI ID: 5939473
• 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
58 GEOSCIENCES
580000 -- Geosciences
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BUILDING MATERIALS
CEMENTS
CENOZOIC ERA
CLAYS
CONTROL SYSTEMS
DEPOSITION
DEVELOPING COUNTRIES
DIAGENESIS
DISSOLUTION
EOCENE EPOCH
EROSION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
HYDROCARBONS
ILLITE
KAOLINITE
LATIN AMERICA
LEACHING
MATERIALS
MINERAL RESOURCES
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXYGEN COMPOUNDS
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
QUARTZ
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTS
SEPARATION PROCESSES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SOUTH AMERICA
TERTIARY PERIOD
VENEZUELA