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Atmospheric CH4 is derived from both natural and anthropogenic sources, and the rapid increase in atmospheric CH4 levels over the past two centuries has predominantly been a result of increased anthropogenic emissions. Nonetheless, natural sources have also changed as a result of global change, and quantifying the fluxes of CH4 from these sources, and their associated climatic feedbacks, is of paramount importance. In this thesis I have developed a method to upscale the global CH4 emissions from UV irradiation of foliar pectin (chapter 2). I have quantified the magnitude and distribution of CH4 emissions from wetlands on a global scale and determined the sensitivity of wetlands to temporal changes in water volume and temperature (chapters 3 and 4). Finally I determine that tropical wetland organic matter decomposition on a global scale behaves non-linearly over seasonal timescales. This implies a substantially different seasonality in CH4 emissions from wetlands (chapter 5). I show that (i) satellites such as MODIS and GRACE can be used to improve the understanding of individual CH4 sources and sinks, and (ii) the newly available satellite observations of CH4 can be effectively used for more than constraining atmospheric chemistry and transport model inversions. Moreover, the work shown in this thesis has contributed new biogenic CH4 source estimates, but has also posed new questions which will ultimately help guide new projects in the atmospheric CH4 research area.

The purpose of this study is to perform simulation studies for a specific coal bed methane reservoir. First, the theory and reservoir engineering aspects of coal bed methane reservoirs, such as dual porosity concept, permeability characteristics of CBM reservoirs and mechanism of gas storage and gas transportation in CBM reservoir have been discussed. Next, simulation results for the CBM reservoir presented. Simulation studies were carried out by using the CBM reservoir simulator, SIMED II. Injection/fall-off test pressure data were interpreted based on the pressure history matching method. The interpretation results include the determination of reservoir permeability and identification of the reservoir altered zone. Also available production histories were used to simulate the reservoir production behavior. Then the production model was used to predict the reservoir future production and to carry out sensitivity analysis on reservoir performance. For natural pressure depletion, methane recovery was increased significantly as reservoir permeability was increased. Well-bore fracturing creates a fractured zone with higher permeability. This increases methane production rate during early time of reservoir life. Reservoir matrix porosity has a significant effect on the reservoir performance. Higher production peak rate and also higher methane recovery was obtained for the reservoir with lower porosity values. Any increase in the reservoir compressibility causes greater reduction in reservoir absolute permeability as well as relative permeability to gas throughout the reservoir. Therefore, methane recovery decreased as the reservoir compressibility increased. The reservoir production behavior was strongly affected by changes in reservoir size. The production peak rate was significantly postponed and lowered as reservoir size was increased. The effect of reservoir initial pressure was investigated and the results show that higher initial reservoir pressure leads to higher production rate during early years of production. However, for the later years of reservoir life, the production profile is almost identical for different initial pressures. Coal desorption time constant affects the methane production by its own scale. In this study, the range of desorption time did not exceed longer than three days and therefore the difference in production rate was observed only in the first few days of production.

Coalbed methane reservoir (CBM) performance is controlled by a complex set of reservoir, geologic, completion and operational parameters and the inter-relationships between those parameters. Therefore in order to understand and analyze CBM prospects, it is necessary to understand the following; (1) the relative importance of each parameter, (2) how they change under different constraints, and (3) what they mean as input parameters to the simulator. CBM exhibits a number of obvious differences from conventional gas reservoirs, one of which is in its modeling. This thesis includes a sensitivity study that provides a fuller understanding of the parameters involved in coalbed methane production, how coalbed methane reservoirs are modeled and the effects of the various modeling parameters on its reservoir performance. A dual porosity coalbed methane simulator is used to model primary production from a single well coal seam, for a variety of coal properties for this work. Varying different coal properties such as desorption time ( τ), initial gas adsorbed (Vi), fracture and matrix permabilities (kf and km), fracture and matrix porosity ( φf and φm), initial fracture and matrix pressure (to enable modeling of saturated and undersaturated reservoirs), we have approximated different types of coals. As part of the work, I will also investigate the modeling parameters that affect the dual peaking behavior observed during production from coalbed methane reservoirs. Generalized correlations, for a 2-D dimensional single well model are developed. The predictive equations can be used to predict the magnitude and time of peak gas rate.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 132 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 132).

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The purpose of this study is to perform simulation studies for a specific coal bed methane reservoir. First, the theory and reservoir engineering aspects of coal bed methane reservoirs, such as dual porosity concept, permeability characteristics of CBM reservoirs and mechanism of gas storage and gas transportation in CBM reservoir have been discussed. Next, simulation results for the CBM reservoir presented. Simulation studies were carried out by using the CBM reservoir simulator, SIMED II. Injection/fall-off test pressure data were interpreted based on the pressure history matching method. The interpretation results include the determination of reservoir permeability and identification of the reservoir altered zone. Also available production histories were used to simulate the reservoir production behavior. Then the production model was used to predict the reservoir future production and to carry out sensitivity analysis on reservoir performance. For natural pressure depletion, methane recovery was increased significantly as reservoir permeability was increased. Well-bore fracturing creates a fractured zone with higher permeability. This increases methane production rate during early time of reservoir life. Reservoir matrix porosity has a significant effect on the reservoir performance. Higher production peak rate and also higher methane recovery was obtained for the reservoir with lower porosity values. Any increase in the reservoir compressibility causes greater reduction in reservoir absolute permeability as well as relative permeability to gas throughout the reservoir. Therefore, methane recovery decreased as the reservoir compressibility increased. The reservoir production behavior was strongly affected by changes in reservoir size. The production peak rate was significantly postponed and lowered as reservoir size was increased. The effect of reservoir initial pressure was investigated and the results show that higher initial reservoir pressure leads to higher production rate during early years of production. However, for the later years of reservoir life, the production profile is almost identical for different initial pressures. Coal desorption time constant affects the methane production by its own scale. In this study, the range of desorption time did not exceed longer than three days and therefore the difference in production rate was observed only in the first few days of production.

The purpose of this study is to perform simulation studies for a specific coal bed methane reservoir. First, the theory and reservoir engineering aspects of coal bed methane reservoirs, such as dual porosity concept, permeability characteristics of CBM reservoirs and mechanism of gas storage and gas transportation in CBM reservoir have been discussed. Next, simulation results for the CBM reservoir presented. Simulation studies were carried out by using the CBM reservoir simulator, SIMED II. Injection/fall-off test pressure data were interpreted based on the pressure history matching method. The interpretation results include the determination of reservoir permeability and identification of the reservoir altered zone. Also available production histories were used to simulate the reservoir production behavior. Then the production model was used to predict the reservoir future production and to carry out sensitivity analysis on reservoir performance. For natural pressure depletion, methane recovery was increased significantly as reservoir permeability was increased. Well-bore fracturing creates a fractured zone with higher permeability. This increases methane production rate during early time of reservoir life. Reservoir matrix porosity has a significant effect on the reservoir performance. Higher production peak rate and also higher methane recovery was obtained for the reservoir with lower porosity values. Any increase in the reservoir compressibility causes greater reduction in reservoir absolute permeability as well as relative permeability to gas throughout the reservoir. Therefore, methane recovery decreased as the reservoir compressibility increased. The reservoir production behavior was strongly affected by changes in reservoir size. The production peak rate was significantly postponed and lowered as reservoir size was increased. The effect of reservoir initial pressure was investigated and the results show that higher initial reservoir pressure leads to higher production rate during early years of production. However, for the later years of reservoir life, the production profile is almost identical for different initial pressures. Coal desorption time constant affects the methane production by its own scale. In this study, the range of desorption time did not exceed longer than three days and therefore the difference in production rate was observed only in the first few days of production.

Thesis (Ph. D.)--Oregon State University, 1992. / Includes mounted photographs. Typescript (photocopy). Includes bibliographical references (leaves 173-186). Also available online.