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Reservoir Heterogeneity as a Controlling Factor to the Abnormal Production Performance of the Albian Age Gas Bearing Sandstone Reservoir, Ibhubesi Oil Field, Orange Basin, South Africa

Fadipe, Oluwaseun A.1; Akinlua, Akinsehinwa 1; Adekola, Adeniyi S.1
1 Earth Sciences, University of the Western Cape, Cape Town, South Africa.

With an upbeat in hydrocarbon exploration effort in the Lower Cretaceous, emphasis is increasingly laid on the sedimentological setting of the Orange basin. The Orange basin was formed during the late Jurassic to early Cretaceous periods due to Gondwana breakup and rifting and later drifting apart of the African and South American plates. It is imperative to understand that the basin consists of siliciclastic sandstone which took its sediment supply from river system with a rivaling delta to the north of the basin.

This paper presents the results of recent findings in the Albian age gas bearing sandstone reservoir of the orange basin. An integrated approach involving a detailed core description, wire line logs, stratigraphic architecture, facies association and seismic interpretation was used to unravel the complexities of the reservoir challenges of the drilled wells in the studied area.

The Albian age successions of the Orange basin typically consist of thick and thin-bedded clay-silt and sand sequences, and occurrence of thin and shaly bed is common. The gas reservoirs within this age consist of an association of coarsening upward, laminated and bioturbated mudstone to massive planar cross-bedded sandstone with evidence of reducing condition.

Petrographic studies using Scanning Electron Microscopy, X-ray diffraction and thin section reveals the presence of some authigenic minerals which have adverse effects on the reservoir performance while the results obtained from the core description, seismic interpretation using the sequence stratigraphic approach clearly show that the environment of deposition ranged between Fluvial and shallow marine settings.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009