Collections > Electronic Theses and Dissertations > Characterization of Methane Storage in Gas Shales Using NMR
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Over the last twenty years technological innovations in the oil industry such as horizontal drilling and hydraulic fracturing have led to the so called 'shale revolution', where gas shale has become one of the most important unconventional hydrocarbon reservoirs on the planet. Gas shale is a porous sedimentary rock composed primarily of compacted fine-grained clay particles which typically has porosoties less than 10%, pore diameters of a few nanometers, and the majority of the porosity is found in the organic matter of the shale. A current topic of debate and focus of research into gas shale reservoirs is how to accurately estimate the gas in-place of gas shale reservoirs, and what role if any does the organic carbon play in the storage potential of the gas shale. Gas shale samples with high and low organic carbon contents show evidence of absorption in the gas shale's organic content and cooperative adsorption of methane due to confinement in gas shale nanopores respectively through an in situ proton nuclear magnetic resonance study of high pressure methane sorption isotherms on crushed gas shale samples. Currently, a combination of the estimated free gas and adsorbed gas that is contained in the prospective area is used to calculate the gas in-place, taking into account the formation's pore size and formation pressure. Cooperative adsorption of methane due to confinement in nanopores provides evidence that there are effective pressures inside the nanopores higher than the pressure typically considered to be that of the shale formation. This mechanism allows for greater than expected densities of methane to be present at lower formation pressures, therefore understanding how this mechanism works in gas shales would allow for better gas in-place estimations, and hopefully increase the amount of natural gas that is technically recoverable.