>Magister Scientiae - MSc / Lab conducted proximate analysis of coal bearing rock units calculates the weight percentage of ash, moisture, fixed carbon and volatile matter through a series of combustion steps. The data obtained is quintessential in establishing the coal rank and in the case of coal bed methane the gas-in-place estimates. In this study 105 proximate analysis samples, from 7 drilled wells, are taken from the south-eastern Kalahari Basin in Botswana. The pseudo proximate analysis, the method proposed in this thesis, calculates the lab proximate analysis results using the neutron, density and gamma ray wireline logs. The uniqueness of the method lies in the fact that no cut off values are needed for the wireline logs, nor are the results of the lab proximate analysis required for calibration. An in depth study of the relationship between the wireline logs and proximate analysis is conducted using a principle component analysis and the results tested using a combination of statistical techniques to determine the significance of the relationship. It is shown that the density and neutron logs model the proportion of ash and volatile matter in the rock matrix, respectively, with a high degree of accuracy. The multiple regression analysis shows that percentages fixed carbon and moisture components of the rock matrix correlate poorly to the proposed well logs, thus most error lies in the determination of these two components. It is statistically proven that the pseudo proximate analysis results are significantly different to the lab measured proximate analysis. This implies that the proposed pseudo proximate analysis method is unable to accurately determine the components of a coal bearing rock matrix using the density, neutron and gamma ray wireline logs. The application of the proposed method is a model to identity the coal bearing rock matrix and provide a predictive estimation of the coal quality, a priori lab measured data.

>Magister Scientiae - MSc / The Kalahari Karoo Basin is one of several basins in southern Africa filled with Late Carboniferous to Jurassic sediments that are primary targets for Permian aged coal. In order to determine the Coalbed Methane (CBM) potential of the Central Kalahari Karoo Basin, 9 exploration boreholes were drilled. Vitrinite reflectance (%Ro) and proximate analysis were conducted on cored coal intervals. Passey’s ΔLogR method used in this thesis employs the use of resistivity and porosity logs to identify and quantify total organic carbon (%TOC) in potential source rocks. Compared with lab measured %Fixed Carbon, the results showed that Passey’s ΔLogR method effectively identifies coal intervals as organic enriched. In terms of %TOC calculations, the method works poorly in coal metamorphosed by dolerite intrusions. These heat affected coal samples display %Ro from 0.77% to 5.53% and were increased in rank from primarily sub-bituminous to higher ranking volatile bituminous and finally to anthracitic coal. Their higher level of organic metamorphism (LOM), accompanying compositional changes and increased density associated with accelerated coal rank seem to have hindered the method in its estimations or lack thereof. Compositional changes in the coal were controlled by proximity to sill intrusion, with a decrease in fixed carbon and volatile matter, and increases in ash and moisture in the contact metamorphism zone (2-12m from sill). In heat unaltered coal that has undergone normal burial maturation characterized by %Ro of 0.44% to 0.65%, the method works very well even attaining accuracy in some samples. In unintruded boreholes CH1 and CH6, correlations between fixed carbon and generated %TOC curves indicate strong relationships with R2 from 0.70 to 0.83. Therefore, it was found that Passey’s ΔLogR method can be applied effectively on coal that has undergone normal burial maturation only.

The Gemsbok Sub-basin is situated in the south-western corner of the Kalahari Karoo Basin and extends south from the Kgalagadi District of Botswana into the Northern Cape (South Africa); and west into the Aranos Basin (southeast Namibia). The Sub-basin preserves a heterogeneous succession of Upper Palaeozoic to Lower Mesozoic sedimentary and volcanic rocks of the Karoo Supergroup. Because the succession is largely covered by the Cenozoic Kalahari Group, the stratigraphy of the succession is not as well understood as the Main Karoo Basin in South Africa. Most research in the Gemsbok Sub-basin is based on borehole data. This study focuses on the intrabasinal correlation, depositional environments and provenance of the Karoo Supergroup in the Gemsbok Sub-basin in Botswana and Namibia. Based on detailed sedimentological analyses of 11 borehole cores of the Karoo Supergroup in the Gemsbok Sub-basin of Botswana and Namibia, 8 facies associations (FAs) comprising 14 lithofacies and 2 trace fossil assemblages (Cruziana and Skolithos ichnofacies) were identified. The facies associations (FA1 to FA8) correspond to the lithostratigraphic subdivisions (the Dwyka Group, Ecca Group, Beaufort equivalent Group, Lebung Group [Mosolotsane and Ntane formations] and Neu Loore Formation) of the Karoo Supergroup. Sedimentological characteristics of the identified facies associations indicate the following depositional environments: glaciomarine or glaciolacustrine (FA1, Dwyka Group), deep-water (lake or sea) (FA2, Ecca Group), prodelta (FA3, Ecca Group), delta front (FA4, Ecca Group), delta plain (FA5, Ecca Group), floodplain (probably shallow lakes) (FA6, Beaufort Group equivalent), fluvial (FA7, Mosolotsane and Neu Loore formations) and aeolian (FA8, Ntane Sandstone Formation). The Dwyka Group (FA1) forms the base of the Karoo Supergroup in the Gemsbok Subbasin and overlain by the Ecca Group deposits. Three types of deltas exist within the Ecca Group: fluvial-dominated; fluvial-wave interaction and wave-dominated deltas. The Gemsbok Sub-basin was characterised by rapid uplift and subsidence and high sediment influx during the deposition of the Ecca Group. Petrographic and geochemical analyses of the Ecca Group sandstones revealed immature arkose and subarkose type sandstones dominated by angular to subangular detrital grains, sourced from transitional continental and basement uplifted source areas. The sandstones of Ntane Sandstone Formation are classified as subarkoses and sourced from the craton interior provenances.