Results of recent drilling of specific lowstand systems tracts targets, the implications to future exploration, and the seismic-sequence stratigraphic model Pletmos basin, offshore South Africa

Conference · Fri Mar 01 00:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5802969

Keenan, J H.G. ^[1]

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1. Soekor Ltd., Parow (South Africa)

The Pletmos basin is a complex series of subbasins off the south coast of South Africa. Depositional styles displayed in the postrift mid-Valanginian to recent sediments reflect the complex interplay of variations in subsidence, sediment supply, eustatic change, and climate. An extensive seismic sequence stratigraphic framework study carried out in 1988 served as the basis for further oil exploration and the evaluation of lowstand systems tracts. Wells were drilled to intersect shelf-margin wedges, basin-floor fans, slope-front fans, prograding lowstand wedges, and incised valley-fill successions depicted by detailed mapping of recent seismic data, integrated with well data. Sequences that apparently resulted from both major and minor downward shift in relative sea level were tested. Although there appears to be adequate sand accumulations on the relict shelf edge in the provenance area, there was little sand in the lowstand target. Seismically, the interpreted lowstand elements are located beyond and below the relict shelf and reflect geometries clearly indicative of component elements of a lowstand systems tract. However, there seems to be some contention about the processes that brought about their deposition. It is important to d toiibe sh between lowstand systems that have been derived by slumping and slope failure, and those that have developed as a result of sediment removal from the shelf and subareal regions during relative sea-level fall. Sand prediction and the relationships between source rock, migration pathways, and reservoir can, therefore, be ascertained with a higher degree of certainty.

• OSTI ID: 5802969
• Report Number(s): CONF-910403-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:3; Conference: Annual meeting of the American Association of Petroleum Geologists (AAPG), Dallas, TX (United States), 7-10 Apr 1991; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
PETROLEUM DEPOSITS
EXPLORATION
SEISMIC SURVEYS
SEDIMENTARY BASINS
PETROLEUM GEOLOGY
STRATIGRAPHY
SOUTH AFRICA
CONTINENTAL SHELF
GEOLOGIC HISTORY
GEOLOGIC MODELS
OFFSHORE SITES
SEDIMENTATION
SEDIMENTS
AFRICA
CONTINENTAL MARGIN
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
GEOPHYSICAL SURVEYS
MINERAL RESOURCES
RESOURCES
SURVEYS
020200* - Petroleum- Reserves
Geology
& Exploration