Design and Application of a Novel Optical Methane Flow Sensor to Quantify Methane Vent Sources at Upstream Oil and Gas Sites

This thesis first describes the development and characterization of an optical methane mass flux sensor, called the VentX, which was designed for use in hazardous locations such as upstream oil and gas facilities for the continuous quantification of methane emissions from point sources.Two configurations were initially described, with directly irradiated photodetectors ultimately favoured over a fully fiber-coupled version.In both configurations a methane volume fraction-dependent velocity measurement error was observed.Following component-by-component investigations of sources of optical interference, a second prototype was then designed and tested that greatly reduced this velocity measurement error, achieving a methane mass flow rate uncertainty of ±0.40 kg/h at 95% confidence and temperature induced measurement drift of <0.015 m/s/K.The VentX was then used to measure casing gas vent rates at eleven Cold Heavy Oil Production with Sand (CHOPS) wells in Saskatchewan, Canada, in conjunction with a larger aerial study of 962 sites using Bridger Photonics' Gas Mapping LiDAR (GML).The time-resolved VentX measurements demonstrated that the discrete GML measurements could reproduce mean venting rates, despite observed temporal variability.Venting from CHOPS sites in this region was shown to be grossly underreported, with approximately 60% of the measured methane originating from wells that appeared to exceed regulated venting limits.However, preliminary economic analysis suggested that 97% of these emissions could be mitigated using readily available combustor technology with payback periods <2 years when costing methane emissions based on current carbon pricing.Finally, the VentX meter was deployed at eight oil wells in Alberta, Canada to measure unsteady venting from production storage tanks, a second key oil and gas sector source.Variable and intermittent venting was documented at multiple sites, often in conjunction with varying methane fraction.Analysis revealed the limitations of using simple gas-to-oil ratios (GOR) to estimate storage tank venting and specific recommendations were made to improve the accuracy of emission measurement and reporting.Finally, statistical analyses showed that discrete measurements of individual storage tanks using so called snapshot technologies should be treated with caution, while providing guidelines for required sample sizes to accurately measure aggregate mean emission rates in larger-scale surveys.Table 2.1: Summary of established bulk velocity or flow rate measurement approaches Technology Requires Fluid-Specific Calibration Factor Pressure Drop Accuracy Requires Flow Conditioning * Turndown Ratio Cost Volumetric Flowrate Measurement Orifice Meter Yes High Fair Yes Poor Low

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