Methane measurements at 90 abandoned, cut & buried onshore wells in Germany

Abandoned oil and gas wells can be significant sources of methane emissions into the atmosphere. However, the extent of these potential emissions is often unclear, and mitigation requires detailed knowledge of the location of emitters. In Germany, the Federal Institute for Geosciences and Natural Resources has investigated a selection of wells of the in total ~25.000 onshore oil and gas wells for the first time. One challenge in investigating these wells is the mandatory decommissioning process, i.e. plugging, cutting and burying. For such soil buried wells, a measurement strategy was developed in which emissions were measured in an area of 30 x 30 m around the well and, for comparison, in a nearby reference area to record the natural background (Jordan et al., 2025). Between 2022 and 2025, nearly 90 wells of varying ages were investigated in northern Germany, where most of Germany's current and historical oil and gas production has taken place. In addition to investigating potential methane and CO₂ emissions, soil gas compositions and stable carbon isotopes (and occasionally also hydrogen isotopes) in the soil gas methane were measured at each study site. In analogy to the reference areas and as is typical for forest, arable, and meadow soils, most well sites acted as methane sinks. Abnormalities compared to the reference areas were only determined at a few wells. For instance, a maximum of ~40 mg h^-1 methane emissions were detected at one well, where small amounts of crude oil also appear to be escaping. However, covering the wells with soil offer an advantage here, as the gas and oil composition geochemically indicates a strong and depth-increasing influence of hydrocarbon-degrading microorganisms (Blumenberg et al., 2025). Final evaluations have not yet been completed, but for Germany, our results indicate that methane emissions from old oil and gas wells are relatively low. Open questions that are currently being addressed include the temporal variability of methane emissions, but also the importance of e.g., seasonal factors on the effectiveness of the microbial filter.