Understanding, Recovery and Management of Hydrogen Sulfide in High-temperature Shale Gas

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At over 30 trillion cubic metres of reserves, shale gas sources will ensure future growth and sustainability of Canadian natural gas, an important low carbon energy source; however, production of this resource requires specialised fracturing and conditioning considerations. Some hot-shale gas reservoirs will exhibit increased amounts of hydrogen sulfide (up to 500 ppm) after a period of production, where hydrogen sulfide plus carbon dioxide must be removed before sales. Removing small amounts of hydrogen sulfide and managing subsequent sulfur from large volumes of gas is not typical for commercial gas processing, particularly when producers do not expect hydrogen sulfide from the early testing of the fluids. This research addresses multiple questions regarding the chemistry of fracturing technologies and treatment of shale gas which contain low-levels of hydrogen sulfide. Understanding where this hydrogen sulfide comes from, how to remove it and how to deal with subsequent sulfur will be investigated through studying fundamental properties of chemical species involved in the reactions of sulfur, sulfate and sulfides under conditions applicable to the production of high-temperature shale gas. High-pressure hydrolysis reactions and sulfate reducing reaction kinetics will be investigated, where the characterisation of intermediate species will be carried out by in situ vibrational spectroscopy and high-pressure gas chromatography. Apparent molar properties for reactants, products and identified intermediates will be determined in order to extrapolate equilibrium relationships to high reservoir and process pressures. All measurements will be carried out in a laboratory with the unique capabilities in high-pressure sour fluid research, including vibration tube densimetry, high-pressure spectroscopy (Raman and IR), high-pressure sour gas adsorption and rheometry equipment.