The Unare lagoon - A recent example of sequence stratigraphic control in reservoir patterns

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

OSTI ID:6068266

Bejarano, C ^[1]

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

The Unare lagoon constitutes a barred coastal lagoon formed during the Holocene transgression on a moderate wave energy, microtidal coast. An extensive surface sampling and core drill program has been carried out in the lagoon in order to develop a reservoir sedimentology and sequence stratigraphic model applicable to similar subsurface deposits. During the rapid Halocene sea level rise, more than 70 m of fluvial and delta plain sediments have aggraded behind the landward stepping coastal barrier. These sediments are truncated seaward by a transgressive wave ravinement surface, and are capped by widespread lagoonal muds which accumulated between 8300 and 7250 yBP. These muds constitute the Holocene Maximum Flooding Surface which preceded the onset of the post Holocene stillstand (c. 500[approximately] yBP), probably as a result of the high rate of sediment supply and the confined nature of the lagoon which acted as an efficient sediment trap. During the post Holocene stillstand, a fluvial-dominated delta has prograded across the lagoon and attained the coastal barrier. This delta constitutes a Highstand Systems Tract. The major reservoir sands comprise distributary channel meanderbelts and the transgressive barrier. The channels form sand ribbons 5-7 m thick, and up to 2 km wide. The barrier and shoreface sands forms a strike-elongate deposits less than 5 m thick, up to 150-600 m wide, and 5-10 km long. The lagoonal facies of the Maximum Flooding Surface form a good reservoir seal overlying the aggrading transgressive fluvial and delta plain sands and muds.

• OSTI ID: 6068266
• 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
CENOZOIC ERA
DEVELOPING COUNTRIES
DISTRIBUTION
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
LATIN AMERICA
MINERAL RESOURCES
OIL SAND DEPOSITS
ORIGIN
PETROLEUM DEPOSITS
QUATERNARY PERIOD
RESOURCE POTENTIAL
RESOURCES
SEDIMENTARY BASINS
SOUTH AMERICA
STRATIGRAPHY
VENEZUELA