Deltaic successions are an important habitat for some of the major world's fossil fuel reserves (i.e. oil, gas and coal). An outcrop analogue study of the excellently exposed Permian siliciclastic Kookfontein deltaic sequence will therefore improve prediction of sandbody geometries and complex internal heterogeneities of subsurface examples.

Preliminary findings from field outcrop log data show the nature of complexity that could be encountered in a deltaic system that fills a basin. The complexity of the Kookfontein deltaic system is reflected in the succession of sedimentary structures (i.e. cross laminations, ripple laminations, Hummocky, massive and homogenous slump layers and horizontal laminations) both in time and space in a more or less an unpredictable manner.

In order to establish a 3D model of the rock record that includes stratigraphic elements and boundaries of all scales, we propose an approach that combines outcrop log, gamma ray log and photo-panel analysis. This approach will allow critical examination of the lateral and vertical variations of facies and their properties regarding fluid flow i.e. geometry and internal heterogeneity. The photo-panel analysis allows 3D high-resolution interpretations of the lithological boundaries both laterally and vertically which cannot be obtained from seismic resolution.

Based on the nature and complexity of the facies association, this study will propose a standard facies model for the deltaic sequence that will test the applicability of Walter's law of facies associations in facies analysis. A 3D reservoir-scale model will then be constructed based on the 3D geological model. The emphasis here will be to depict possible errors that could arise if all the stratigraphic elements and their boundaries (both on small and large scales) are not fully incorporated into reservoir scale modelling.

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