Constraining offshore methane leakage from plugged and abandoned petroleum wells using marine microbial genomics

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Based on estimates derived from studies in the North Sea and Gulf of Mexico, Canada's 620 east coast wells could be emitting as much as 2 million tonnes of methane per year, a total volume equivalent to 160 million tonnes of carbon dioxide. To date there has been no research to identify the extent to which methane leakage above background levels is occurring, how much enters the atmosphere, the role methanotrophic (methane eating) microorganisms play in mitigating its release, and the potential for new genomics-based biotechnologies to accelerate and enhance remediation.Over a 20-year time scale, methane emissions have a climate warming potential as much as 84 times that of carbon dioxide and represent a significant environmental concern. The Government of Canada joined more than 100 countries as a signatory to the Global Methane Pledge at the COP26 summit in 2021 committing Canada to exceed current regulatory requirements (aimed at a 40-45% reduction by 2025) and to develop new regulatory measures to reduce oil and gas methane emissions by at least 75% below 2012 levels by 2030. To date, regulatory authorities do not require assessment of potential subsea methane leakage as it is assumed that these leaks are mitigated - but they are not. It is critical that this regulatory chasm is better understood with rigorous science that will inform policy and government strategy, both provincially and nationally, for net zero emissions.Microbiologists and geochemists from the University of Calgary and Saint Mary's University will partner with other universities, the private sector (Stantec, Pro Oceanus, Kraken Robotics, Dominion Diving), and government organizations (Nova Scotia Dept of Natural Resources & Renewables) to fill this knowledge gap through a comprehensive survey of abandoned well sites in the offshore of Nova Scotia to collect seabed sediment, water column and atmospheric samples in proximity to recently abandoned and legacy well sites to address these questions. The results of the project will provide the basis for policy development and regulations for greenhouse gas emissions reduction, as well as tools to mitigate methane emissions from both abandoned and future offshore petroleum wells.