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PhD. (Geology) / The lithology, stratigraphy, metamorphism and structure of the rocks in a highly deformed and metamorphosed terrain, some 5 000 km 2 in extent, south of the Soutpansberg in the Northern Transvaal, are described. The Bandelierkop Formation, which is comprised of Ultramafic-, Mafic- and Pelitic gneisses occur as deformed and metamorphosed remnants in tonalitic grey granitoids known as the Baviaanskloof Gneiss. The Ultramafic- and Mafic gneisses of the Bandelierkop Formation, in which granulite grade mineral assemblages exist, are chemically equivalent to peridotitic and basaltic komatiites and basaltic tholeiites of Archaean greenstone terrains. The greenstone origin for the gneisses is also indicated by the Hout River traverse in which material, at the lower to middle amphibolite facies, becomes progressively metamorphosed and deformed over a distance of 10 km to the granulite grade of metamorphism. The Pelitic gneiss of the Bandelierkop. Formation is chemically similar to greywackes and shales of the Fig Tree Group and Belvue Road Formations of the Swaziland sequence. The area of investigation is divided into two high-grade metamorphic zones separated by an eastnortheast trending Orthopyroxene isograd. The rocks of the Orthopyroxene zone to the north of the isograd were subjected to two events of regional metamorphism (M 1 and M2 ). The area south of the isograd, known as the Orthoamphibole zone, is characterised by the presence of silverygrey anthophyllite blades in Pelitic gneiss which formed during the M3 event. The southern limit of the Orthoamphibole zone, in the south-eastern portion of the area is poorly exposed and thus less well defined.

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Throughout the James Ranges and Gardiner Range the Arumbera Sandstone forms prominent strike ridges with distinctive dark reddish slopes and pale red to orange-white cliffs. Because of their lithologic and stratigraphic similarities, the names Eninta and ''Quandong" for these units should be suppressed in favor of the name of Arumbera Sandstone, which has precedence. The stratigraphic and lithologic differences observed between the Quandong Conglomerate in the type locality and the Arumbera Sandstone in the study area suggest that these units are not equivalent. Similarites with the Areyonga Formation suggest the Quandong Conglomerate could be part of the Areyonga Formation. Lithofacies la, ld, and 2b, and Unit 3 of the Arumbera and its equivalents are typically recessive arkoses, subarkose, and mudrocks. They are interpreted as nearshore-marine to coastal deltaic deposits which include intertonguing tidal-flat, tidal-channel, and beach sediments. Lithofacies 1b and 2a consist of cliff-forming arkoses, subarkoses, and lithic arkoses. Lithofacies 2c is also resistant, and consists of orthoconglomerates and conglomeratic sandstones. Lithofacies 1e is moderately resistant, and consists of paraconglomerates, conglomeratic sandstones, and mudrocks. It and lithofacies 2c contain pebbles and small cobbles of chert, quartzite, vein quartz, silicified ooids, and limestone, dolostone, shale, and sandstone. These four lithofacies are interpreted as braidplain and fluvial sheet sands. In the east-central part of the Amadeus Basin the Arumbera Sandstone probably was deposited in a coastal environment as a sequence of deltaic sediments that was dominated by fluvial processes. The Arumbera Sandstone appears to be the molasse derived from the Late Proterozoic and Early Cambrian Petermann Ranges orogeny. Source rocks include sedimentary, low- to middle-rank metamorphic, and plutonic granites. Grain mineralogy and weathering characteristics suggest a hot, semiarid climate during deposition of the Arumbera. The Arumbera Sandstone and Quandong Conglomerate contain fair to good porosity and permeability, and petrographic evidence shows mesogenetic generation of secondary porosity. Previous and present burial depths are adequate for the generation of petroleum. The presence of suitable underlying .source rocks, overlying salt of the Chandler for a seal, and stratigraphic and structural traps suggest a good potential for petroleum. Production of dry gas from the lower part of the Arumbera at Dingo field, north of Deep Well Homestead, confirms the petroleum potential of this formation.

Hydraulic Fracturing is a technique to accelerate production and enhance ultimate recovery of oil and gas while fracture geometry is an important aspect in hydraulic fracturing design and optimization. Systematic design procedures are available based on the so-called two-dimensional models (2D) focus on the optimization of fracture length and width, assuming one can estimate a value for fracture height, while so-called pseudo three dimensional (p-3D) models suitable for multi-layered reservoirs aim to maximize well production by optimizing fracture geometry, including fracture height, half-length and width at the end of the stimulation treatment. The proposed p-3D approach to design integrates four parts: 1) containment layers discretization to allow for a range of plausible fracture heights, 2) the Unified Fracture Design (UFD) model to calculate the fracture half-length and width, 3) the PKN or KGD models to predict hydraulic fracture geometry and the associated net pressure and other treatment parameters, and, finally, 4) Linear Elastic Fracture Mechanics (LEFM) to calculate fracture height. The aim is to find convergence of fracture height and net pressure. Net pressure distribution plays an important role when the fracture is propagating in the reservoir. In multi-layered reservoirs, the net pressure of each layer varies as a result of different rock properties. This study considers the contributions of all layers to the stress intensity factor at the fracture tips to find the final equilibrium height defined by the condition where the fracture toughness equals the calculated stress intensity factor based on LEFM. Other than maximizing production, another obvious application of this research is to prevent the fracture from propagating into unintended layers (i.e. gas cap and/or aquifer). Therefore, this study can aid fracture design by pointing out: (1) Treating pressure needed to optimize fracture geometry, (2) The containment top and bottom layers of a multi-layered reservoir, (3) The upwards and downwards growth of the fracture tip from the crack center.