Onshore equivalents of the main Kudu gas reservoir in Namibia.

Article in Edited Volumes
(Original article)


Publication Details

Author(s): Stanistreet IG, Stollhofen H
Editor(s): Cameron, N.R., Bate, R.H., Clure, V.S.
Title edited volumes: The oil and gas habitats of the South Atlantic
Publisher: Geological Society Publishing House
Publishing place: London
Publication year: 1999
Title of series: Special Publication
Volume: 153
Pages range: 345-365
ISSN: 0305-8719
Language: English


Abstract


Radiometric dates of Jurassic and Cretaceous flood basalts of the southern South Atlantic maritimes have thrown the stratigraphic contexts of Karoo and post-Karoo sequences into considerable question. Central to the problem is the status of volcano-sedimentary units, characterized by aeolian-related sedimentary interlayers, containing evaporites and other lacustrine elements. The main Kudu gas reservoir ('Lower Gas Sand') offshore Namibia, interleaved with undated flood basalts, is a prime example. A previously proposed onshore correlate is the fluvio-aeolian Etjo Sandstone, with a central Namibian type area, and comparisons have been made, particularly with units traditionally classified as Etjo Sandstone, near the Etendeka Plateau base in northwest Namibia, now recognized to be of younger age. We time-correlate the main Kudu Sandstone reservoir, however, with evaporitic fluvio-lacustrine and aeolian interlayers beneath and interleaved with Early Jurassic Kalkrand flood basalts of southern Namibia, situated onshore almost directly opposite the Kudu Field. The main Kudu Sandstone reservoir is transitional in palaeoenvironmental setting between Early Jurassic onshore analogues. Main Kudu reservoir geometries and associated lithologies can be better constrained with knowledge derived from Kalkrand sedimentary interlayers and their tectonic and volcanic controls. Kalkrand interlayer thicknesses are controlled primarily by down-to-the-east extensional fault system half-graben geometries, antithetic to an inferred down-to-the-west master detachment. Within resulting sub-basinal accommodation space, lava topography controlled thickness variation. When Kalkrand insights are taken into account with radiometric dating and biostratigraphy, a Namibian Mesozoic framework fixes Kudu reservoirs and analogues into a southern Gondwanan context. At least in its type area in central Namibia, the Etjo Formation is Early Jurassic, discounting a previously proposed widespread <100 Ma hiatus along a sub-Etjo disconformity. Instead, sequence boundary hiatuses of Permian-Triassic, Early Jurassic and Middle Jurassic-Early Cretaceous ages represent time-stratigraphic gaps, relating to major faulting episodes, recording extensional events associated with continental margin evolution. Understanding onshore analogues and refining the Namibian Mesozoic framework should help constrain seismic analysis of the Namibian margin and hydrocarbon reservoir geometries. Consequently, exploration focus should widen to include Karoo sequences beneath the basal Early Cretaceous transgression.



FAU Authors / FAU Editors

Stollhofen, Harald Prof. Dr.
Lehrstuhl für Geologie (Exogene Dynamik)


External institutions with authors

The University of Liverpool


How to cite

APA:
Stanistreet, I.G., & Stollhofen, H. (1999). Onshore equivalents of the main Kudu gas reservoir in Namibia. In Cameron, N.R., Bate, R.H., Clure, V.S. (Eds.), The oil and gas habitats of the South Atlantic. (pp. 345-365). London: Geological Society Publishing House.

MLA:
Stanistreet, Ian G., and Harald Stollhofen. "Onshore equivalents of the main Kudu gas reservoir in Namibia." The oil and gas habitats of the South Atlantic. Ed. Cameron, N.R., Bate, R.H., Clure, V.S., London: Geological Society Publishing House, 1999. 345-365.

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Last updated on 2019-28-01 at 07:08