We are pleased to announce that three G360 team members were awarded the BP Safety Star in June of this year for their safe practices while performing field work at the Alice Street Site, a site that has been an active G360 research site as part of an NSERC CRD project under Dr. Beth Parker since 2014.
Here is an extract of the award nomination:
“During a Senior Management Observation, it was observed that the three University of Guelph students working on the project did an excellent job in identifying trip and slip hazards at the job site. A packer test was being performed on a well in order to measure vertical temperature changes in the well in order to evaluate groundwater flow in the bedrock. As part of the test, there were coils of wiring and tubing laying on the ground between the well and support trailer. The students placed caution tape around the area and placed several traffic cones on the edges. This was implemented on their own without any coaching or comments from AECOM supervisors. I personally thanked them and recognized them for doing a great job in identifying hazards and making the work area safe.”
Congratulations to Jonathan Munn, Carlos Maldaner, and Jeremy Fernandes.
We are pleased to announce the publication of a new open access journal article in the Journal of Contaminant Hydrology by G360 researchers in collaboration with researchers from the Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia.
Fugitive methane (CH4) leakage associated with conventional and unconventional petroleum development (e.g., shale gas) may pose significant risks to shallow groundwater. While the potential threat of stray (CH4) gas in aquifers has been acknowledged, few studies have examined the nature of its migration and fate in a shallow groundwater flow system. This study examines the geophysical responses observed from surface during a 72 day field-scale simulated CH4 leak in an unconfined sandy aquifer at Canadian Forces Base Borden, Canada, to better understand the transient behaviour of fugitive CH4 gas in the subsurface. Time-lapse ground-penetrating radar (GPR) and electrical resistivity tomography (ERT) were used to monitor the distribution and migration of the gas-phase and assess any impacts to groundwater hydrochemistry. Geophysical measurements captured the transient formation of a CH4 gas plume emanating from the injector, which was accompanied by an increase in total dissolved gas pressure (PTDG). Subsequent reductions in PTDG were accompanied by reduced bulk resistivity around the injector along with an increase in the GPR reflectivity along horizontal bedding reflectors farther downgradient. Repeat temporal GPR reflection profiling identified three events with major peaks in reflectivity, interpreted to represent episodic lateral CH4 gas release events into the aquifer. Here, a gradual increase in PTDG near the injector caused a sudden lateral breakthrough of gas in the direction of groundwater flow, causing free-phase CH4 to migrate much farther than anticipated based on groundwater advection. CH4 accumulated along subtle permeability boundaries demarcated by grain-scale bedding within the aquifer characteristic of numerous Borden-aquifer multi-phase flow experiments. Diminishing reflectivity over a period of days to weeks suggests buoyancy-driven migration to the vadose zone and/or CH4 dissolution into groundwater. Lateral and vertical CH4 migration was primarily governed by subtle, yet measurable heterogeneity and anisotropy in the aquifer.
This research was made possible through an NSERC Strategic Partnerships Grant Project (SPG-P) awarded to Drs. John Cherry and Beth Parker (principal investigators), and collaborators Drs. Bernhard Mayer, Ulrich Mayer and Cathryn Ryan. Dr. Aaron Cahill provided a major role with proposal writing, experimental design and overall project management, both with field implementation and project reporting, and is now a research associate at the University of British Columbia Department of Earth, Oceanic and Atmospheric Sciences. An NSERC Banting Fellowship provided support to Dr. Colby Steelman.
Expansion of shale gas extraction has fuelled global concern about the potential impact of fugitive methane on groundwater and climate. Although methane leakage from wells is well documented, the consequences on groundwater remain sparsely studied and are thought by some to be minor. Here we present the results of a 72-day methane gas injection experiment into a shallow, flat-lying sand aquifer. In our experiment, although a significant fraction of methane vented to the atmosphere, an equal portion remained in the groundwater. We find that methane migration in the aquifer was governed by subtle grain-scale bedding that impeded buoyant free-phase gas flow and led to episodic releases of free-phase gas. The result was lateral migration of gas beyond that expected by groundwater advection alone. Methane persisted in the groundwater zone despite active growth of methanotrophic bacteria, although much of the methane that vented into the vadose zone was oxidized. Our findings demonstrate that even small-volume releases of methane gas can cause extensive and persistent free phase and solute plumes emanating from leaks that are detectable only by contaminant hydrogeology monitoring at high resolution.