Methane emissions from abandoned coal and oil and gas developments in New Brunswick and Nova Scotia
Energy reserves have been exploited in the Atlantic Canadian provinces since the early 1600s, and many fossil fuel extraction sites have been abandoned over this long history of energy development. Oil, natural gas, and coal extraction sites are a source of greenhouse gas emissions, particularly for methane (CH4). In this study, we used multiple sampling methods to measure CH4 from abandoned coal mine openings in Nova Scotia and a legacy oilfield in New Brunswick. Atmospheric and shallow soil gases were sampled around legacy sites using flux rate chamber measurements (spatial and temporal) and plot-scale atmospheric gas surveys, in addition to regional gas screening surveys over larger populations of sites to confirm whether small-scale observations were reflected regionally. Only one oil and gas site (2.4 ± 3.1⋅ 102 mg m− 2 day− 1) and one abandoned coal mine opening (1.0 ± 1.1⋅ 102 mg m− 2 day− 1) were affected by soil CH4 migration, though rates of leakage were minimal and would rank as low severity on industrial scales. Plot-scale atmospheric gas screening showed super-ambient CH4 concentrations at 5 sites in total (n = 16), 2 coal adits and 3 abandoned oil and gas wells. Regional gas screening surveys suggest that 11% of legacy oil and gas sites have some emission impacts, compared with 1–2% of legacy coal sites. These frequencies are close, albeit lower than the 15% of legacy oil and gas sites and 10% of abandoned coal mine openings flagged from our aggregated small-scale observations. These sites may emit less than other developments studied to date either because more time has elapsed since extraction, or because differences in regional geology reduce the likelihood of sustained emissions. This study provides valuable information to help understand the methane emission risks associated with legacy energy sites.
KeywordsMethane emissions Geochemical analysis Abandoned fossil fuel sites Soil gas flux Atmospheric gas sampling
I would like to acknowledge Siobhan Semadeni for revising this manuscript as well as other works of mine throughout the years.
- Allen, D.T., Torres, V.M., Thomas, J., Sullivan, D.W., Harrison, M, Hendler, A., Herndon, S.C., Kolb, C.E., Fraser, M.P., Hill, A, Allen, D. (2013). Measurements of methane emissions at natural gas production sites in the United States. Proceedings of the National Academy of Sciences, 110 (44), 17768–17773.CrossRefGoogle Scholar
- Atherton, E., Risk, D., Fougere, C.M., Marshall, A., Williams, J.P., Werring, J., Minions, C. (2017). Mobile measurement of methane emissions from natural gas developments in Northeastern British Columbia, Canada. Atmospheric Chemistry & Physics, 17(20).Google Scholar
- Caulton, D.R, Shepson, P.B, Santoro, R.L., Sparks, J.P., Howarth, R.W., Ingraffea, A.R., Cambaliza, M.O.L., Sweeney, C., Karion, A., Davis, K.J. (2014). Experimental investigation of wellbore integrity and CO2-brine flow along the casing-cement microannulus. Proceedings of the National Academy of Sciences, 201316546.Google Scholar
- Collier, SM, Ruark, MD, Oates, LG, Jokela, WE, Dell, CJ. (2014). Measurement of greenhouse gas flux from agricultural soils using static chambers. Journal of visualized experiments:, JoVE, 90.Google Scholar
- Environment and Climate Change Canada. (2017). Canadian environmental sustainability indicators: Greenhouse gas emissions. Resource document. Government of Canada. http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=En&n=FBF8455E-1. Accessed 22 January 2018.
- Environment and Climate Change Canada. (2018). Technical backgrounder: Federal methane regulations for the upstream oil and gas sector. Resource document. Government of Canada. http://www.canada.ca/en/environment-climate-change/news/2018/04/federal-methane-regulations-for-the-upstream-oil-and-gas-sector.html. Accessed 9 November 2018.
- Erno, B, Schmitz, R, et al. (1996). Global atmospheric methane: budget, changes and dangers. Journal of Canadian Petroleum Technology, 35(07).Google Scholar
- Henderson, J.A.L. (1940). The development of oil and gas in New Brunswick. Canadian Institute of Mining and Metallurgy.Google Scholar
- Howie, RD. (1968). Stony Creek gas and oil field, New Brunswick. AAPG Special Volumes.Google Scholar
- Hu, S, Zhang, AO, Feng, G, Guo, X, Miu, X, Li, C, Han, D, Wang, J, Kang, L. (2018). Methane extraction from abandoned mines by surface vertical wells: A case study in China. Geofluids.Google Scholar
- Jackson, RB, Vengosh, A, Darrah, TH, Warner, NR, Down, A, Poreda, RJ, Osborn, SG, Zhao, K, Karr, JD. (2013). Increased stray gas abundance in a subset of drinking water wells near Marcellus Shale gas extraction. Proceedings of the National Academy of Sciences, 110(28), 11250–11255.CrossRefGoogle Scholar
- O’Connell, E, Risk, D, Atherton, E, Bourlon, E, Fougere, C, Baillie, J, Lowry, D, Johnson, J. (2019). Methane emissions from contrasting production regions within Alberta, Canada: Implications under incoming federal methane regulations. Elementa, Science of the Anthropocene, 7(1).Google Scholar
- Peter, C.S.T. (1993). Maritimes Basin evolution: key geologic and seismic evidence from the Moncton Subbasin of New Brunswick. Atlantic Geology.Google Scholar
- Pihlatie, MK, Christiansen, JR, Aaltonen, H, Korhonen, JFJ, Nordbo, A, Rasilo, T, Benanti, G, Giebels, M, Helmy, M, Sheehy, J. (1993). Comparison of static chambers to measure CH4 emissions from soils. Agricultural and forest meteorology, 171, 124–136.Google Scholar
- Watson, TL, Bachu, S, et al. (2007). Evaluation of the potential for gas and CO2 leakage along wellbores. E&P Environmental and Safety Conference.Google Scholar