Reservoir heterogeneity of the sandstone reservoirs within the Pletmos basin, block11a, offshore South Africa

Abstract

This study is aimed at illustrating the reservoir heterogeneity in the BCII - BCI interval of the Ga-field, offshore South Africa. This was achieved by generating a conceptual static model as a predictive tool for the BCII - BCI interval. The reservoir zones between BCII - BCI were sub divided into two major zones, viz: zone A and zone B. Petrophysical analysis was conducted on the three wells Ga-A3, Ga-Q1 and Ga-Q2. The application of the sequential gaussian algorithm ensured that all of the available data was honoured to the highest extent in generating the realisations to display the heterogeneity of the BCII – BCI sandstone reservoir. Sampling values from the well logs were extrapolated into the 3D grid. Each reservoir contained a percentage of shale or clay of about 45% -50%. Small scaled reservoir heterogeneity has been construed to the influence of the sedimentary structures. Large scaled reservoir heterogeneity has been identified, due to the lateral extent of the claystones which is widely distributed throughout the study area