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Financial liabilities and environmental implications of unplugged wells for the Gulf of Mexico and coastal waters


Plugging and abandoning (P&Aing) wells is a policy priority because unplugged wells present potential financial and environmental risks to the public. Offshore wells, compared with land wells, generally produce more, cost more to P&A and present different environmental risks. Here we estimate that the cost to P&A all 14,000 unplugged, non-producing wells in US Gulf of Mexico offshore waters, inland waters and wetlands is US$30 billion. Wells in shallower waters closer to shore make up 90% of inactive wells but only 25% of total P&A costs. They also present larger environmental risks. Prior owners of wells in federal waters (deeper and farther from shore) can be held liable for P&A costs if the current owner does not P&A them. We find that 88% of outstanding P&A liability in federal waters is associated with wells currently or formerly owned by one of the large, financially stable ‘supermajor’ companies.

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Fig. 1: Cumulative probability well resumes production within s months after pausing production.

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With the exception of data from Enverus, all data are publicly available via Harvard Dataverse ( Commercial Enverus data were made available to us through Enverus’ academic programme.

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We thank the Center for Global Energy Policy at Columbia University for supporting this work.

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M.A. and G.B.U. conceived the paper, analysed data and wrote the manuscript. B.S. wrote the manuscript. S.N. analysed data and wrote the manuscript.

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Correspondence to Mark Agerton.

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Agerton, M., Narra, S., Snyder, B. et al. Financial liabilities and environmental implications of unplugged wells for the Gulf of Mexico and coastal waters. Nat Energy 8, 536–547 (2023).

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