According to the US Environmental Protection Agency, orphan wells are unplugged or plugged gas and oil wells with no recent production. The relationship between orphan wells and climate change is discussed in this article.
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Orphan wells are no longer functional, maintained, or operable and cannot be restored as a functional well site other than by a government agency since the responsible party has abandoned the site. In the United States alone, Bourdot et al. (2022) found over 120 000 orphan wells, with the majority having no information on the depth of the well or the last production date.
Why are Orphan Wells a Risk to the Environment?
The abandonment of wells poses risks to human and environmental health. Cahill et al. (2019) found that orphan wells leak into groundwater reservoirs and the atmosphere. The contamination of drinking water and air can therefore induce detrimental health effects in surrounding areas to people but also damage critical ecosystems. Moreover, orphan wells often leak greenhouse gases since they remain unplugged, thus releasing gases such as methane into the atmosphere despite being no longer functional.
How are Orphan Wells Monitored?
The liabilities of orphan wells have prompted government agencies to monitor documented wells to prevent leaking into surrounding environments. Alboiu and Walker (2019) discussed monitoring orphan wells in Canada, describing how the wells are often monitored using soil surface methane testing and gas detection surveys annually. However, due to many abandoned wells, sensor technologies are increasingly used to monitor abandoned wells and their surrounding sites (Demetillo et al. 2019).
Can Orphan Wells Contribute to Climate Change?
A study by Burdot et al. found that orphan wells in the US release 0.016 ± 0.001 MMt of methane on average every year, corresponding to 5-6% of total methane emissions of the US. As a result, orphan wells directly contribute to greenhouse gas emissions worldwide and exacerbate the effects of global climate change. Moreover, the threats to water resources of orphan wells, including surface spills, wastewater disposal, and drinking water contamination through poor well integrity, can lead to the release of stored carbon dioxide in soil and underground ecosystems.
Therefore, despite being no longer operational or functional, orphan wells contribute to climate change through greenhouse gas emissions and disruptions to surrounding ecosystems. The impacts of orphan wells also have no representatives to manage the potential fallout or prevent impacts from occurring by plugging the wells and ensuring the absence of leakage. As a result, orphan wells are only monitored by government agencies unaware of the true extent of their existence, which may jeopardize critical ecosystem services.
Orphan Wells: The Future
The transition towards sustainable energy systems is critical to curbing the release of further greenhouse gas emissions. However, the same transition means that the rate of orphaned wells is rapidly accelerating due to their undesirable energy production methods. A significant number of wells also translates to worsened impacts from potential leaks.
To address the growing number of orphan wells, several solutions have been developed to identify better, monitor, and manage the sites. Firstly, identifying orphan wells and their characteristics is required since corporations are not obliged to do so. For instance, the study by Bourdot et al. (2022) was the first step toward finding the complete set of wells eligible to be plugged and remediated in the US. However, the authors emphasize that the number of sites is likely an underestimation and that the number of orphan wells is closer to 1 million sites in the US alone.
Secondly, once orphan wells have been identified, sites may be monitored for leaks using environmental sensors before remediation. Technological improvements have allowed the release of methane to be tracked closely, as was done by Demetillo et al. (2019) using wireless sensor network technology in aquatic areas. The prototype sensor is attached to a buoy that relays information that can be tracked online, allowing stakeholders or agencies to monitor many sites easily.
Finally, orphan wells may be plugged and sites restored. Information gathered from sensors in surrounding soil and aquatic systems may benefit the identification of orphan wells that are environmental risks and may be a priority to remediate. However, the sole responsibility of plugging and restoring sites falls on government agencies that lack the resources to target all existing areas.
The contribution of orphan wells to climate change will likely continue in the coming years as a growing number of functional wells will be abandoned, and government agencies will attempt to remediate existing sites.
Sensor technologies and policies are improving the monitoring and tracking these abandoned wells but only represent reactive rather than proactive strategies. Addressing the issue of greenhouse gas emissions and pollution by non-functional energy systems will be a significant challenge as the world transitions toward more sustainable energy-producing methods.
References and Further Reading
Alboiu, V., & Walker, T. R. (2019). Pollution, management, and mitigation of idle and orphaned oil and gas wells in Alberta, Canada. Environmental Monitoring and Assessment, 191(10). https://link.springer.com/article/10.1007/s10661-019-7780-x
Boutot, J., Peltz, A. S., McVay, R., & Kang, M. (2022). Documented Orphaned Oil and Gas Wells Across the United States. Environ. Sci. Technol., 56(20), pp. 14228–14236. https://pubs.acs.org/doi/10.1021/acs.est.2c03268
Cahill, A. G., Beckie, R., Ladd, B., Sandl, E., Goetz, M., Chao, J., Soares, J. G., Manning, C. C., Chopra, C., Finke, N., Hawthorne, I., Black, A. P., Mayer, K. H., Crowe, S. A., Cary, T., Lauer, R. M., Mayer, B., Allen, A. E., Kirste, D., & Welch, L. (2019). Advancing knowledge of gas migration and fugitive gas from energy wells in northeast British Columbia, Canada. Greenhouse Gases-Science and Technology, 9(2), pp. 134–151. https://onlinelibrary.wiley.com/doi/10.1002/ghg.1856
Demetillo, A. T., Japitana, M. V., & Taboada, E. B. (2019). A system for monitoring water quality in a large aquatic area using wireless sensor network technology. Sustainable Environment Research, 29(1). https://sustainenvironres.biomedcentral.com/articles/10.1186/s42834-019-0009-4
Jackson, R. B., Vengosh, A., Carey, J. W., Davies, R. J., Darrah, T. H., O’Sullivan, F., & Pétron, G. (2014). The Environmental Costs and Benefits of Fracking. Annual Review of Environment and Resources, 39(1), pp. 327–362. https://www.annualreviews.org/doi/10.1146/annurev-environ-031113-144051