Field Assessment of Subsurface Migration, Groundwater Impacts and Fate of Fugitive Methane from Energy Resource Development in a Northeastern British Columbian Setting

Lead Proponent

University of British Columbia

Project Background

Fugitive methane emissions from energy wells can migrate through complex subsurface pathways, impact groundwater quality, and contribute to atmospheric greenhouse gas release, yet the processes controlling these pathways remain poorly constrained. This project carried out one of the first multidisciplinary, field-scale controlled natural gas release experiments in Northeastern British Columbia, integrating geochemistry, hydrogeology, geophysics, soil-gas monitoring and atmospheric measurements. The work aimed to resolve how methane moves through heterogeneous near-surface sediments, how much is attenuated by dissolution and microbial oxidation, and what fraction ultimately reaches the atmosphere under realistic field conditions.

Results

The project showed that methane migration is strongly governed by the architecture of glaciofluvial sediments, with permeable sand-and-gravel units enabling lateral migration while finer materials restricted vertical movement. Most (i.e. ~75%) of the injected methane remained in the subsurface, where it dissolved into groundwater and underwent measurable microbial oxidation, producing clear geochemical and isotopic signatures. Only a relatively small proportion (~25%) escaped to the atmosphere, with subsurface fluxes found to be highly dynamic dependant on fluctuations of atmospheric pressure.

The work produced several advances in monitoring and detection. Time-lapse geophysical imaging was able to better characterize the lateral extent of the gas plume compared to what was possible using conventional point measurements. Eddy covariance provided the first integrated site-scale methane emission estimates at such a controlled release site, confirming low atmospheric loss relative to the total injected mass. Rapid-response molecular and isotopic fingerprinting was successful in distinguishing injected gas from background sources. Together, these findings can assist in designing future monitoring programs, interpreting leakage events, and assessing the environmental consequences of fugitive methane in active energy-development regions.