Sequence stratigraphic patterns and reservoir implications in the Oligocene and Cretaceous, Northern Monagas, Eastern Venezuela

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

OSTI ID:6067387

Montes, J L; Rojas de Salazar, A ^[1]

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1. Corpoven S.A., Puerto la Cruz (Venezuela)

A sedimentological study based on 876 ft of core, electric logs, and cuttings from the well MUC-20 in Mulata field, Northern Monagas, has shown that the Cretaceous to Oligocene section exhibits a variety of facies, ranging from coarse-grained cross-stratified sands, fine-grained bioturbated sands, marine mudstones with varying proportions of silt and thin coal seams. These sediments accumulated in environments varying from fluvial to deltaic to marine shelf. The study of stacking patterns and facies successions indicates that six type I sequence boundaries are visible in the Cretaceous to Oligocene section. The lowest sequence boundary is Maestrichtian and is an incised valley complex filled with lowstand fluvial sandstones. The overlying sequence boundary is interpreted to be at the Cretaceous-Paleocene boundary (68 m.y. ) and is overlain by estuarine transgressive tract deposits. The third sequence boundary is thought to represent the 30 my eustatic sea level fall and incorporates a major stratigraphic hiatus from the lower Paleocene to Upper Oligocene. This sequence boundary is overlain by estuarine transgressive tract deposits. The other three sequence boundaries were recognized within the Upper Oligocene and are capped by nearshore and coastal sediments comprising coastal barrier and tidal inlet sandstones, and marsh and lagoonal mudstones. The sediments overlying the fourth and fifth sequence boundaries are interpreted as lowstand shoreline deposits. The uppermost sequence boundary is represented by barrier sandstone transgressive tract deposits. The identification of these sequence boundaries and the parasequences comprising the systems tracts formed the basis for fieldwide reservoir correlations which enabled detailed mapping of the individual reservoir units. The Maestrichtian fluvial incised valley complex forms a widespread sand sheet, whereas the transgressive barrier sandstones are more restricted, and tend to shale out laterally.

• OSTI ID: 6067387
• 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
BOUNDARY LAYERS
CENOZOIC ERA
COAL DEPOSITS
COAL SEAMS
CORRELATIONS
CRETACEOUS PERIOD
DEPOSITS
DEVELOPING COUNTRIES
DRILL CORES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
LATIN AMERICA
LAYERS
LEVELS
MAPPING
MESOZOIC ERA
MINERAL RESOURCES
OIL FIELDS
OIL WELLS
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCES
ROCKS
SAND
SANDSTONES
SEA LEVEL
SEDIMENTARY ROCKS
SEDIMENTS
SILT
SOUTH AMERICA
TERTIARY PERIOD
VENEZUELA
WELLS