Methane at abandoned wells onshore

Country / Region: Germany

Begin of project: January 1, 2021

End of project: December 31, 2025

Status of project: January 13, 2022

Methane is the second most important greenhouse gas in climate change, and reducing methane emissions to the atmosphere is considered essential to achieve a large effect in reducing negative climate impacts on short time scales. Old, abandoned wells of the oil and gas industry are considered a possible source of methane. Recently, the US EPA included abandoned wells for the first time in its National Inventory Reports to the IPCC with comparatively small shares of the total natural gas supply chain, which includes production, transport and distribution (EPA, 2019). However, such extrapolative estimates are considered uncertain because they are based only to a very limited extent on actual measurements. Only a few corresponding measurement campaigns have been carried out and these primarily in North America (e.g., Kang et al., 2014), but also the Netherlands (Schout et al., 2019). Recently, initial investigations have been carried out in the area of the German exclusive economic zone (EEZ) in the North Sea, and methane escape could not be detected at the old wells analysed there (Römer et al., 2021). For Germany, with its approximately 20,000 deep, onshore abandoned wells of different ages, no corresponding data are available so far. The role of a microbial "methane filter" in the soil column and groundwater is also unclear, as microorganisms are able to convert methane aerobically and anaerobically. In addition to the significantly higher number of onshore boreholes, it can be assumed that old onshore wells have due to the lacking water column a tentatively higher relevance as an atmospheric methane source compared to boreholes in the oceans if their integrity is affected. In this project, therefore, investigations of methane concentrations are carried out at representatively selected boreholes in several areas in Lower Saxony. In addition to analyses in the direct vicinity of boreholes, the surrounding natural methane situation in groundwater and soil (e.g. Schloemer et al., 2018) will also be taken into account and these situations will be investigated with the help of carbon isotope and geomicrobiological analyses.

Location of deep boreholes exemplary for the region around Hannover (Lower Saxony). The boreholes have different ages and development status (data from NIBIS map server; https://nibis.lbeg.de/cardomap3/ ). The marked areas are representative of selected target areas for investigations in the project. Most of the wells in the figure are abandoned wells, which in Germany are usually filled former production or exploration wells of the hydrocarbon industry Source: LBEG

Literature:

• EPA (2019) EPA - Inventory of U.S. Greenhouse Gas Emissions and Sinks - 1990 - 2017. EPA. (https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2017)
• Kang, M., Kanno, C.M., Reid, M.C., Zhang, X., Mauzerall, D.L., Celia, M.A., Chen, Y. and Onstott, T.C. (2014) Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania. Proceedings of the National Academy of Sciences, 201408315. (https://www.pnas.org/content/111/51/18173)
• Römer, M., Blumenberg, M., Heeschen, K., Schloemer, S., Müller, H., Müller, S., Hilgenfeldt, C., Barckhausen, U. and Schwalenberg, K. (2021) Seafloor methane seepage related to salt diapirism in the northwestern part of the German North Sea. Frontiers in Earth Science 9, 556329. (https://www.frontiersin.org/articles/10.3389/feart.2021.556329/full)
• Schloemer, S., Oest, J., Illing, C.J., Elbracht, J., Blumenberg, M., 2018. Spatial distribution and temporal variation of methane, ethane and propane background levels in shallow aquifers – A case study from Lower Saxony (Germany). Journal of Hydrology: Regional Studies 19, 57-79. (https://doi.org/10.1016/j.ejrh.2018.07.002)
• Schout, G., Griffioen, J., Hassanizadeh, S.M., Cardon de Lichtbuer, G. and Hartog, N. (2019) Occurrence and fate of methane leakage from cut and buried abandoned gas wells in the Netherlands. Science of The Total Environment 659, 773-782. (https://doi.org/10.1016/j.scitotenv.2018.12.339)