--> Abstract: Integration of Reservoir and Source Distribution with Seismic-Sequence Stratigraphy and Geophysical Modeling in the Discovery of Hydrocarbons within a Cretaceous Sequence, Bredasdorp Basin, South Africa, by S. J. Winters, G. J. Brink, and S. Kuhlmann; #91012 (1992).
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ABSTRACT: Integration of Reservoir and Source Distribution with Seismic-Sequence Stratigraphy and Geophysical Modeling in the Discovery of Hydrocarbons within a Cretaceous Sequence, Bredasdorp Basin, South Africa

WINTERS, S. J., G. J. BRINK, and S. KUHLMANN, SOEKOR, Parow, South Africa

The third-order Aptian sequence, bounded by Type 1 unconformities, consists of a lowstand sequence set, within which fourth-order sequences are developed. A transgressive flood surface demarcates the termination of lowstand sequence-set deposition. The overlying transgressive Previous HitsystemsNext Hit tract is characterized by onlap-infill reflection configurations and significant marine-condensed section development which is associated with good quality, oil-prone, source shales throughout the central basin area. A maximum flood surface separates the transgressive Previous HitsystemsNext Hit tract from the highstand tract.

The lowstand sequence set consists of fourth-order sequences containing lowstand turbidite and highstand deltaic Previous HitsystemsNext Hit developed on the falling limb of a third-order Previous HitseaNext Hit Previous HitlevelNext Hit Previous HitcycleNext Hit. A turbidite system is associated with relative Previous HitseaNext Hit Previous HitlevelNext Hit falls resulting in stage development that is both allocyclic and retrogradational. Massive, amalgamated fan-lobe and depositional channel sandstones within the turbidite system comprise the primary reservoir targets that were successfully tested by three wells. These good quality reservoirs are 30 to 50 m in thickness are are seismically depicted by large negative impedance contrasts. The presence of overlying fan-abandonment facies furthermore induces anomalously high amplitude events, which facilitate stratigraphic delineation of reservoir geome ries. The presence of hydrocarbons may further be corroborated by GEOSTACK anomalies. Trapping mechanisms are both fault dependent and stratigraphic.

The temporal development of higher-order sequences and Previous HitsystemsNext Hit Previous HittractsTop promoted favorable reservoir and source-rock emplacement in the basin depocenter.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)