Fugitive methane gas migration around Alberta's petroleum wells

Methane emission quantification from gas migration (GM) and surface casing vent flow (SCVF) is needed to support strategic methane reduction targets and mitigate explosion and groundwater quality risks. This paper assessed which of 451 990 Alberta oil and gas wells should have been (or will be) tested for SCVG and/or GM according to regulations, and compared the results with the provincial GM testing database. As of 2017, GM testing was required on 3.5%, and reported for 0.75%, of Alberta's energy wells. Similarly, SCVF testing was required on 58.2%, and reported for 6.2%, of all wells. An estimated 14.5% of all wells were legally abandoned before GM and SCVF testing regulations existed. All of the remaining wells will require SCVF testing prior to legal abandonment, and an estimated 32.9% to 75.5% of the total will not require GM testing before abandonment based on current regulations. The cumulative number of 'serious' GM reports that have remained open since submission has continuously been increasing each year, which contradicts the requirement for repair within 90 days, suggesting regulations are not enforced. The GM testing procedure is inadequate for quantitative testing. We conclude that fugitive methane emissions, and in particular gas migration, are now well constrained in Alberta. (c) 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.