Methane emissions from abandoned wells? A German case study
Bibliographic record
Abstract
Methane recently became the focus of attention as the target to slow global warming in the near future. Hence, measures to reduce anthropogenic methane emission are globally discussed and researchers test methods to actively reduce atmospheric methane levels. Complicating advancement in this field, there are still high uncertainties associated with methane sources and sinks. One example is the methane emission from abandoned oil and gas wells. The USA, with about 4,000,000 abandoned wells, is the only country worldwide to include emissions from these wells in their yearly greenhouse gas emissions inventory. Studies estimated that these emissions account for about 1–13% of the U.S. energy sector (Williams et al. 2021). In addition to the USA, only a few countries like Canada, the United Kingdom and the Netherlands collected data on methane emissions from abandoned gas wells. Currently Germany has about 20,000 abandoned wells (formerly productive and dry wells) of different ages, which were generally filled and buried and since 1950s officially have to be plugged, cut, and buried at the end of their lifecycle. It is unclear, whether they are emitting methane or not. Here, we present our project to fill this knowledge gap for Germany and focus on onshore-abandoned oil & gas wells and their potential to emit methane. Therefore, we will measure soil-atmosphere methane fluxes at several abandoned wells exemplary in four regions of Lower Saxony (Federal State in Northern Germany). In case of methane emission to the atmosphere, we will determine the origin of the methane in soil gas at 1 m depth by isotopic analyses. In addition to these analyses in the direct vicinity of the boreholes, we will investigate the surrounding natural methane situation in groundwater and soil with the help of molecular-geomicrobiological methods and determinations of methane oxidation rates. Williams, J. P., Regehr, A., & Kang, M. (2021). Methane Emissions from Abandoned Oil and Gas Wells in Canada and the United States. Environ Sci Technol, 55(1), 563-570. https://doi.org/10.1021/acs.est.0c04265
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".