Control of facies, burial history, and oil migration on diagenesis and reservoir quality: Maracaribo basin, Venezuela

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6755112

Ghosh, S K; Di Croce, J; Isea, A; Gonzalez, C ^[1]

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1. Intevep S.A., Caracas (Venezuela)

This regional study of the Eocene Misoa Formation is the first attempt to decipher the role of depositional facies, burial history, and timing of oil migration on diagenetic make-up and reservoir quality in the Maracaibo basin. Subsurface data including cores from 11 wells along a northwest-southeast transect in the Urdaneta, Lagunillas, and Barua-Motatan fields reveal that the depositional facies of the three sandstones range from mainly fluvial (Urdaneta) to deltaic-coastal marine in Lagunillas, and typically sublittoral in the Barua-Motatan area. Both authigenic mineralogy and vitrinite reflectance data suggest progressively greater subsidence from the northwest to southeast. Thus, diagenetic grade is immature on the northwest in Urdaneta and mature to supermature in Barua-Moutan where greater mineralogical diversity and porosity/permeability reduction were noted. Similarly, compaction effects are minimum in Urdaneta, and maximum in Barua-Motatan where porosity is highly reduced, and is totally secondary in nature. Other factors, such as grain size, presence of early pore-lining chlorite (in marine facies), infiltrated grain-coating clays (in fluvial facies), and proximity of reservoirs to the post-Eocene unconformity surface also helped preserve or enhance porosity. Timing of oil migration also contributed to variable regional distribution of porosity and permeability. An early migration in the Urdaneta area helped retain much of the original porosity. In contrast, relatively late migration during upper Miocene, especially in the Barua-Motatan area on the southeast, permitted unimpeded silicification and pressure solution, and consequent destruction of all primary porosity.

• OSTI ID: 6755112
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
PETROLEUM DEPOSITS
RESERVOIR ROCK
VENEZUELA
DIAGENESIS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
MATURATION
MIGRATION
PERMEABILITY
POROSITY
SEDIMENTARY BASINS
TERTIARY PERIOD
VITRINITE
CENOZOIC ERA
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
LATIN AMERICA
MACERALS
MINERAL RESOURCES
RESOURCES
SOUTH AMERICA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences