Skip to main content
Dryad

Data from: Using controlled subsurface releases to investigate the effect of leak variation on above-ground natural gas detection

Mbua, Mercy1; Riddick, Stuart N.1; Tian, Shanru2; Cheptonui, Fancy1; Houlihan, Cade1; Smits, Kathleen M.2; Zimmerle, Daniel1

Research facility: Colorado State University
Published Nov 05, 2023 on Dryad. https://doi.org/10.5061/dryad.ncjsxkt15

Data files

Nov 05, 2023 version files 152.15 MB

Abstract

Pipelines transport natural gas (NG) in all stages between production and the end user. The NG composition, pipeline depth, and pressure vary significantly between extraction and consumption. As methane (CH4­), the primary component of NG is both explosive and a potent greenhouse gas, NG leaks from underground pipelines pose both a safety and environmental threat. Leaks are typically found when an observer detects a CH4 enhancement as they pass through the downwind above-ground NG plume. The likelihood of detecting a plume depends, in part, on the size of the plume, which is contingent on both environmental conditions and intrinsic characteristics of the leak. To investigate the effects of leak characteristics, this study uses controlled NG release experiments to observe how the above-ground plume width changes with changes in the gas composition of the NG, leak rate, and depth of the subsurface emission. Results show that plume width generally decreases when heavier hydrocarbons are present, the leak rate is reduced, and as leak depth decreases from 0.9 to 0.6 m. The above surface CH4 plume is undetectable when leaks are 1.8 m deep. As most survey methods typically prioritize leaks based on the leak size, this study shows that the effect of NG density on above-ground plume width is only 4%, equivalent to the effect of leak rate. This suggests that reported leaks in areas with heavier hydrocarbons could currently be missed or underestimated. Furthermore, this study shows that leaks from pipelines laid in covers meeting minimum depth requirements of 0.9 m could be easier to detect compared to those buried shallower. Overall, this study illustrates that leak survey protocols for flowlines and gathering lines should be different from distribution pipelines and tailored to the compositions of the transported NG to report emissions accurately.