Geology and hydrocarbon reservoir potential of the Pituil and Barreal Formations, Calingasta Valley, western Argentina
- Texaco Inc., Houston, TX (USA)
- Texaco Petrolera Argentina S.A., Buenos Aires (Argentina)
The Calingasta basin is one of the north-south-trending intermontane basins informally known as the Bolsones. The stratigraphy consists of lower Paleozoic metamorphic basement overlain by sediments and volcanics of upper Paleozoic through Cenozoic age. Three distinct geological provinces are recognized within the Bolsones region: Sierras Pampeanas, Precordillera, and Cordillera Frontal. Outcrop samples from the Permian Pituil and Triassic Barreal formations from the Tamberias region of the Sierras Pampeanas province were analyzed to determine the composition, porosity type, and diagenetic modification. The Pituil formation is a shallow marine sequence overlying Carboniferous glaciomarine sediments. They grade eastward into nonmarine lacustrine, deltaic, and fluvial sandstones. The rocks are fine- to medium-grained litharenites with porosities of 6-10 %. Diagenetic modifications include quartz overgrowths, unstable grain dissolution, carbonate cements, pyrite, and kaolinite. Triassic deposits occur on the western flank of the Precordillera, overlying a basement of volcanics and metasedimentary rocks. The Triassic sediments can be several hundreds of meters thick; deposition occurred in fluvial to lacustrine environments. These clastic sediments are considered to be northern extensions of the hydrocarbon-productive sediments in the Cuyo basin. The Barreal formation ranges from clay-rich lithic wackes and shales to conglomeratic, volcaniclastic litharenites and sublitharenites. Framework grains consist of quartz, feldspars, rock fragments, and, rarely, glass shards. Cements include zeolites, carbonates, chalcedony, pyrite, and clays. Tuffs are found at certain intervals within the section; alteration to iron-rich smectite is common. Reservoir potential is highly variable. Porosities range from as low as 5% to greater than 25%.
- OSTI ID:
- 6985561
- 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
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Related Subjects
58 GEOSCIENCES
ARGENTINA
PETROLEUM DEPOSITS
RESERVOIR ROCK
DIAGENESIS
CARBONIFEROUS PERIOD
CONGLOMERATES
DISSOLUTION
FELDSPARS
GEOLOGIC FORMATIONS
KAOLINITE
PERMEABILITY
POROSITY
PYRITE
QUARTZ
SEDIMENTARY BASINS
STRATIGRAPHY
TRIASSIC PERIOD
TUFF
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CHALCOGENIDES
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
IRON COMPOUNDS
IRON SULFIDES
LATIN AMERICA
MESOZOIC ERA
MINERAL RESOURCES
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALEOZOIC ERA
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SOUTH AMERICA
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences