Abundances and sources of methane close to selected abandoned wells in the German North Sea

Country / Region: Germany / German North Sea

Begin of project: January 1, 2019

End of project: December 31, 2021

Status of project: December 14, 2020

Deployment of GOLDEN EYE during research cruise HE357 with RV Heincke near abandoned wells in the German North Sea Source: BGR

Recent studies have addressed methane seepage escaping near abandoned drill sites in the Central North Sea. These “shallow gas” releases with a possible anthropogenic component may be a relevant and so far unconsidered methane source to the North Sea. In the here described BGR project the respective situation close to selected drill holes in the German North Sea is addressed, particularly where the presence of “shallow gas” was indicated by seismic data (Müller et al., 2018). During a research cruise with RV Heincke (July 2019; headed by BGR-scientist Dr. Katrin Schwalenberg) geochemical, geophysical and hydro acoustic investigations were undertaken in the German North Sea as well as at the Dutch Dogger Bank. Geochemical studies were used to gain information on the potential sources of dissolved methane (biogenic versus thermogenic; e.g., Schlömer et al., 2018). Electromagnetic methods, including the deep-towed BGR-system GOLDEN EYE (see image) were applied to assess sediment porosities and to localize methane seepages and shallow gas in the sediments (also with the equipped cameras, a CTD and methane sensor). Hydroacoustic on-board systems were used to identify gas bubbles in sediment and water column (e.g. Römer et al., 2017). First evaluations of the data demonstrated in parts of the working area up to 10-times enriched concentrations in dissolved methane. These enrichments appear to be related to natural methane seeps. Further details on cruise HE537 can be found here. In the frame of a planned research cruise with RV Maria S. Merian (MSM98; cruise leader: Dr. Miriam Römer, Marum Bremen) in January 2021 it is intended to study additional abandoned wells as well as to better characterize the natural seep setting in the central North sea.

Literature:

• Blumenberg, M., Schwalenberg, K. 2020. Dem Nordsee-Methan auf der Spur. In „BGR-Report 2020, 18-19“ (in German).
• Müller, S., Reinhardt, L., Franke, D., Gaedicke, C., Winsemann, J., 2018. Shallow gas accumulations in the German North Sea. Mar. Petrol. Geol. 91, 139-151. (https://doi.org/10.1016/j.marpetgeo.2017.12.016)
• Römer, M., Wenau, S., Mau, S., Veloso, M., Greinert, J., Schlüter, M., Bohrmann, G., 2017. Assessing marine gas emission activity and contribution to the atmospheric methane inventory: A multidisciplinary approach from the Dutch Dogger Bank seep area (North Sea). Geochemistry Geophysics Geosystems. (https://doi.org/10.1002/2017GC006995)
• 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)