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CO2lloquium: Surface casing vent flow

April 29, 2016 @ 1:00 pm - 3:00 pm

WHO: Kirk Osadetz, Programs Development Manager, CMC’s Containment and Monitoring Institute
LOCATION: Rm. 128, CMC Research Institutes, 3535 Research Road NW, Calgary, AB
RSVP: joan.smart@cmcghg.com, 403 210-7104


The fate of all petroleum is to migrate to the surface where it enters soils, water bodies and the atmosphere.  This effect is illustrated by natural seeps.  Unfortunately natural seeps are often difficult to identify, episodically active and their emissions contributions are not well quantified.  In contrast, petroleum leakage from wellbores, both petroleum and water wells, is better identified, especially for petroleum wells, where leakage is closely monitored and remediation is required.

Wellbore leakage has well-established impacts on soil, plants and the atmosphere, as the effects of natural petroleum gas leakage are also a feature of landfills, coal mines, gas transportation systems and agriculture, among other activities.  The key potential impacts of such leakages are on:

  • Safety – where explosive limits are reached or poisoning or asphyxia occurs.
  • Vegetation and crops, which is well studied, easily identified, but for which specific exposure limits are not understood.
  • The atmosphere – where, the effects of either methane or the additional carbon dioxide have known potential climate impacts.

Despite extensive study, and climate inventories of methane emissions from all sources, the monitoring efforts have been small.  There are clear discrepancies between “top-down” atmospherically-based geophysical monitoring results and “bottom-up” geochemically-based monitoring results. Added to this are site specific monitoring variations that can differ by up to six orders of magnitude.  As a result we cannot confidently rank the relative importance of different specific methane sources.

Nor do we know if one emitter is currently operating under more stringent regulation or restrictions than others. While this may seem surprising in the presence of the IPCC inventories, most of the inventories are calculated not from monitored results, but from measurements not directly indicative of the methane flux in the shallow subsurface or the atmosphere. Neither do the IPCC inventories adequately account for the variable impact of soil cover on the atmospheric flux, even though specific monitoring studies indicated the importance of microbial soil processes that either consume or produce methane. Where the bottom-up methods are source specific they are hampered by irregular geographic rate variations and the episodic nature of the emission rate into both soils and the atmosphere. While the top-down methods are comprehensive they are also largely indiscriminant regarding the relative atmospheric contributions from different potential sources.

It appears that, in Canada, the issue of wellbore leakage is potentially less significant than other sources, specifically land-fills, although there are significantly more of the former sources than the later. Similarities between sources of American and Canadian atmospheric emissions are not established, and the American results appear contradictory to Canadian air quality surveys. The recent “top-down” surveys have increased methane emissions estimates for the United States, largely attributable to petroleum industry activities. The same may not be characteristic of Canada, possibly because of differences in flaring policies and practices in the two countries. A renewed effort to develop both best monitoring practice for mutually informing and reconciling “top-down” and “bottom-up” monitoring efforts should be undertaken, specific to Canadian conditions and practices.

About the speaker

Kirk Osadetz is the Programs Development Manager for the Containment and Monitoring Institute (CaMI), a business division of CMC Research Institutes Inc. The institute is developing and demonstrating technology and practice that serves and assists Canadian corporations dealing with carbon management and subsurface containment issues and requirements, including safe resource extraction and disposal or storage in subsurface geological media. Previously he worked for the National Geological Survey as a sedimentary basin geoscientist.  He was been an active member of both the Canadian Society of Petroleum Geologists and Calgary’s geoscience community.


April 29, 2016
1:00 pm - 3:00 pm
Event Category:


University Research Centre
Rm. 128, 3535 Research Road NW
Calgary, Alberta Canada
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403 210-7104