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In today's energy constrained world, carbon capture and sequestration can play an essential role in mitigating greenhouse gas emissions, while simultaneously maintaining a robust and affordable energy supply. This technology is an end-of-pipe solution that does not contribute to a decrease of the production of greenhouse gases, but is very useful as a transition solution on the way towards other sustainable energy production mechanisms. This research involves the development of a comprehensive decision making framework for assessing the techno-economic feasibility of CO2 sequestration in unmineable coal seams, with the Central Appalachian Basin chosen for analysis due to the availability of empirical data generated through recent characterization and field validation studies. The studies were conducted in order to assess the sequestration capacity of coal seams in the Central Appalachian Basin and their potential for enhanced coal bed methane recovery. The first stage of this research involves assessment of three major sequestration performance parameters: capacity, injectivity, and containment. The assessment is focused on different attributes and reservoir properties, characteristic of deep unmineable coal seams in the Central Appalachian Basin. Quantitative and qualitative conclusions obtained through this review process are used later in the identification of the minimum set of technical information necessary for effective design and development of CO2 storage operations. The second section of this dissertation analyzes economic aspects of CO2 sequestration. This segment of the research uses a real options analysis to evaluate the impact of major sources of uncertainty on the total cost of developing and operating a CCS project in a regulatory environment that expects implementation of carbon taxes, but with uncertainty about the timing of this penalty. Finally, all quantitative and qualitative information generated in the first two stages of this research were used for development of a decision making framework/matrix that summarizes the interactions between major technical and economic parameters and constraints, on the other hand, and their impact on overall feasibility of CO2 sequestration in unmineable coal seams. This framework will provide user with capability to address complex problems in a more systematic way and to analyze the most efficient way to utilize available resources. / Ph. D.

Coal seams in the Waikato Coal Measures can vary significantly in thickness over distances of hundreds of meters to kilometers. Previously, the primary depositional controls on these variations have been inferred to be syn-depositional normal faulting and pre-depositional paleotopography. The data presented in support of these models are typically equivocal and which, if any, of these processes provide the principal control on the geometry and spatial distribution of coal seams in the Waikato Coal Region is uncertain. This study utilizes a large database of drill-logs, seismic-reflection lines and mine exposures in four areas (Huntly, Maramarua, North HuntlylWaikare and Rotowaro Coalfields) to test whether syn-depositional faulting and/or paleotopography influence coal seam architecture. These data were used to construct cross sections across faults and basement topography, which in turn, offer information on the relative timing of faulting and coal measure deposition, together with information on the spatial relations between seam thicknesses, faulting and paleotopography. Cross sections and isopach maps together with examination of spatial and temporal variations in fault displacements reveal that syn-depositional normal faulting had little or no impact on the deposition of the Waikato Coal Measures. Only in the Maramarua study area was any evidence found of fault control on coal measure deposition, with the Landing Fault accruing displacement between deposition of the Kupalrupa Seam and the end of coal measure sedimentation. The vast majority of faults in the Waikato Coalfield were, however, active following coal measure deposition. For example, the Foote, Kimihia and Pukekapia faults show evidence of displacement accrual, which commenced during deposition of the Mangakotuku Formation (37-35 Ma BP). The duration of this episode of faulting is difficult to determine, but may have ceased about 30 Ma ago. In addition, a number of faults (e.g. Foote Fault) display evidence oflate stage extension during the last 5 Ma. Given the lack of stratigraphic evidence for fault displacements during deposition of coal measures, it is suggested that the Mangakotuku and Waipuna basement scarps are erosional rather than tectonic features. Cross sections, together with structure contour and isopach maps in each of the four study areas examined, indicate that basement topography was the dominant control on the spatially variable accumulation of peat. These data show coal seams both thinning into, and away from, topographic lows. To account for this observation a model is proposed, in which peat accumulation is controlled by basement relief and sediment supply to parts of the depositional system. In the model it is postulated that the Waikato Coal Measures depositional system was a continuum between two end members. In one end member, with a high sediment supply, sediment is channeled into the lowest topographic areas and peat accumulates mainly on topographic highs. In the other end member, with little or no sediment supply, peat accumulates to its greatest thickness in areas of relatively low topography, in addition to on basement ridges. In the Rotowaro and North Huntly/Waikare study areas, the thickest peat developed on basement highs and the lows acted as a conduit for sedimentation. On basement highs, peat mires were largely sheltered from clastic sediment influx. In the Huntly East and Maramarua study areas, the thickest peat accumulated in basement lows, with comparable clastic sedimentation in highs and lows. The proposed model has application to other coalfields where peat accumulated on an undulating topographic surface and sediment supply was channelised. Prediction of coal seam thickness, as well as lithological types, is crucial in coal exploration and development. The methodology developed and employed in this study can be applied to other basins to access and model coal and clastic sediment distribution.

Coal seams in the Waikato Coal Measures can vary significantly in thickness over distances of hundreds of meters to kilometers. Previously, the primary depositional controls on these variations have been inferred to be syn-depositional normal faulting and pre-depositional paleotopography. The data presented in support of these models are typically equivocal and which, if any, of these processes provide the principal control on the geometry and spatial distribution of coal seams in the Waikato Coal Region is uncertain. This study utilizes a large database of drill-logs, seismic-reflection lines and mine exposures in four areas (Huntly, Maramarua, North HuntlylWaikare and Rotowaro Coalfields) to test whether syn-depositional faulting and/or paleotopography influence coal seam architecture. These data were used to construct cross sections across faults and basement topography, which in turn, offer information on the relative timing of faulting and coal measure deposition, together with information on the spatial relations between seam thicknesses, faulting and paleotopography. Cross sections and isopach maps together with examination of spatial and temporal variations in fault displacements reveal that syn-depositional normal faulting had little or no impact on the deposition of the Waikato Coal Measures. Only in the Maramarua study area was any evidence found of fault control on coal measure deposition, with the Landing Fault accruing displacement between deposition of the Kupalrupa Seam and the end of coal measure sedimentation. The vast majority of faults in the Waikato Coalfield were, however, active following coal measure deposition. For example, the Foote, Kimihia and Pukekapia faults show evidence of displacement accrual, which commenced during deposition of the Mangakotuku Formation (37-35 Ma BP). The duration of this episode of faulting is difficult to determine, but may have ceased about 30 Ma ago. In addition, a number of faults (e.g. Foote Fault) display evidence oflate stage extension during the last 5 Ma. Given the lack of stratigraphic evidence for fault displacements during deposition of coal measures, it is suggested that the Mangakotuku and Waipuna basement scarps are erosional rather than tectonic features. Cross sections, together with structure contour and isopach maps in each of the four study areas examined, indicate that basement topography was the dominant control on the spatially variable accumulation of peat. These data show coal seams both thinning into, and away from, topographic lows. To account for this observation a model is proposed, in which peat accumulation is controlled by basement relief and sediment supply to parts of the depositional system. In the model it is postulated that the Waikato Coal Measures depositional system was a continuum between two end members. In one end member, with a high sediment supply, sediment is channeled into the lowest topographic areas and peat accumulates mainly on topographic highs. In the other end member, with little or no sediment supply, peat accumulates to its greatest thickness in areas of relatively low topography, in addition to on basement ridges. In the Rotowaro and North Huntly/Waikare study areas, the thickest peat developed on basement highs and the lows acted as a conduit for sedimentation. On basement highs, peat mires were largely sheltered from clastic sediment influx. In the Huntly East and Maramarua study areas, the thickest peat accumulated in basement lows, with comparable clastic sedimentation in highs and lows. The proposed model has application to other coalfields where peat accumulated on an undulating topographic surface and sediment supply was channelised. Prediction of coal seam thickness, as well as lithological types, is crucial in coal exploration and development. The methodology developed and employed in this study can be applied to other basins to access and model coal and clastic sediment distribution.

>Magister Scientiae - MSc / The fracture porosity and permeability of the Beaufort Seam 1 (BS1) and Ecca coal seams of the Waterberg Basin have been comprehensively characterised with the aid of geophysical wire‐line logs. The main aim of the thesis was to estimate the porosity and permeability of the coal seams using down‐hole wire‐line data; comparing results from injection falloff test to establish the validity of the technique as a fast an effective method. The study area is the largely under explored Karoo‐aged, fault bounded Waterberg basin Located in the Limpopo Province of South Africa. The study employed mainly the density and dual lateral resistivity logging data (Las format) from eight wells (WTB45, WTB48, WTB56, WTB58, WTB62, WTB65, WTB70 and WTB72). Density logging data was used for coal identification and fracture porosity estimation while fracture permeability was estimated from dual lateralog resistivity data. Analysis of fracture porosity required coal cementation indices and fracture width as an input parameter. These were estimated with the aid of water pump out test data, coal quality and gas analysis data provided by Anglo Coal in addition to the above mention logs. The collection of sheet coal model was used to represent anisotropic coal reservoirs with non‐uniform fracture system was used to represent these coals. The mathematical formulas used to estimate both fracture porosity and permeability took into account the above coal model. The theoretical formulas are a modification from both Darcy’s equation and Archie’s equations. The coal seams were encountered at depths ranging from 198m to 385m in the wells and were marked by low density and very high resistivity. From the estimated results the coal reservoirs are characterised by high cementation indices ranging from 0.82 to 2.42, very low fracture porosity and low fracture permeability. Estimated results show that coal reservoir fracture porosity ranged from 0.0002% to 0.33% for both BS1 and Ecca seams. Estimated results also show that coal reservoir permeability ranged from 0.0045mD to 6.05mD in the BS1 formation and from 0.01 to 0.107mD in the Ecca. Results when compared with those of injection falloff test shows that the estimated permeability is slightly lower as expected since the model did not account for coal anisopropy. The fracture permeability was found to decrease with increase in vitrinite content, coal rank, coal burial depth and increases with increase in inertinite content. On a basinal scale the model estimated permeability was found to increase slightly from the east to the west of the basin. The porosity decreases with increase cementation index for deeper coal seams and increases with increase cementation index for shallower coal seams.