Date of Award:

2017

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geology

Advisor/Chair:

Benjamin Burger

Abstract

Emissions of methane, non-methane hydrocarbons (NMHC), and carbon dioxide (CO2) at 27 natural gas well pads, 11 non-well locations in oil and gas fields, and 7 hydrocarbon-bearing outcrops in eastern Utah between 2013 and 2016 were measured using a dynamic flux chamber (DFC) in effort to answer the following questions: What effect does the development of oil and gas have on the observed air quality (increased ozone, CO2, volatile organic compounds (VOCs), and/or methane emissions) in northeastern Utah? What percentage of these gases is due to natural background emissions, and what percentage is due to oil and gas development in the region? Methane emissions were the focus of this study, but emissions of other compounds were also measured to better understand the sources and characteristics of emissions. Background methane fluxes were all (mg) meter (m)-2 hour (h)-1. Methane emissions from well pad soils were commonly higher closer to the wellhead, though exceptions existed. Methane fluxes from well pad soils ranged from -5.6 to 70,000 mg m-2h-1. Based on analysis of NMHC emissions data, emissions from 68% of the sampled well pad soils were due to leaks of raw natural gas, whereas the remaining emissions were likely from a combination of raw gas leaks, liquid hydrocarbon spills, and/or methanogenic processes. CO2 emissions were higher than methane emissions 92% of the time at well sites, possibly due to CO2 in natural gas, and/or CO2 emitted from bacterial decomposition of soil organic matter and/or fossil hydrocarbons. Total combustible soil gas concentrations were measured at 21 wells. In summer 2015, soil properties were also analyzed to better understand well leakage. Wells categorized as shut-in had the highest average methane fluxes. Measured methane soil emissions were scaled-up for the entire Uinta Basin to estimate the overall emission from well pad soils, and to compare soil emissions with other natural gas-related sources. Producing and shut-in gas wells were estimated to emit 16.1 ± 4.3 and 8.6 ± 3.2 (90% confidence interval) t y-1 (tonne/year) of methane in the Uinta Basin, respectively, which is

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