Delineation of Oil And Gas Fields In the Bredasdorp Basin, Offshore South Africa, Using Seismic Attribute Mapping, Seismic Inversion And AVO Techniques.

The E-BD oil and the E-CE oil and gas accumulations occur as separate reservoirs consisting of amalgamated deep-marine sandstones. Large areas of these reservoirs are close to or below seismic tuning thickness. A suite of geophysical techniques have been applied to a 3D seismic data volume covering these fields in order to determine their geometries. The techniques employed include seismic amplitude mapping, seismic correlation, seismic inversion and AVO processing. These methods were evaluated and used to assist the interpretation, often complementing each other. In this way, geological models for sandstone distribution have been derived which explain the lack of communication between hydrocarbon-bearing and water-bearing sandstones, and the nature of the reservoir facies encountered in boreholes. This has led to a better assessment of the in-place hydrocarbon volumes and upside potential of these fields.