14,000 uncapped gas and oil wells put climate and marine ecosystems at risk

It would cost over $30 billion to plug the inactive wells, with big oil companies responsible for most of the cost.
Ameya Paleja
Offshore oil production facility
Offshore oil production facility

nielubieklonu/ iStock 

More than 14,000 oil and gas wells in the Gulf of Mexico remain uncapped and could potentially harm the marine ecosystems and contribute to global warming, according to a study recently published by researchers at the University of California, Davis.

As per U.S. laws, oil and gas well operators are legally required to plug the wells once production at the site has ceded. The process is fairly straightforward, with the upper area of the borehole required to be plugged by cement and then covered with sediment. The piping can then be cut off, and the site is abandoned.

Left unplugged, the well continues to seep hydrocarbons like methane which can be digested by microbial life but is then converted to carbon dioxide, which makes its way into the atmosphere. Heavier molecules remain unprocessed and become contaminants putting marine ecosystems at risk.

Are all oil and gas wells capped?

With severe risks associated with uncapping of wells, laws in the U.S. mandate that wells are capped off post their use. However, when researchers looked at data about wells only along the Gulf of Mexico, which includes the states of Alabama, Louisiana, Mississippi, and Texas, they found that over 14,000 wells were not producing nor were permanently capped.

Proportionally, the number is still rather small considering that the region is home to over 82,000 wells. However, given that more than 64,000 of these wells have been retired and capped, 14,000 is still a large number.

14,000 uncapped gas and oil wells put climate and marine ecosystems at risk
Onshore gas and oil production facility

According to Ars Technica's report, about 3,500 of these wells have a temporary cap, meaning they could be revived if fossil fuel prices fluctuate too much or better technology becomes available. However, their revival is unlikely since previous data has shown that less than four percent of wells that have been inactive for five years return to production again.

Plugging the well can be a costly affair depending on its location. Those in shallow waters can be plugged at $660,000 per foot, while deeper waters cost over $1 million per foot for the same job. With roughly 1,600 wells in deep water locations, the cost of capping them is estimated to exceed $35 billion.

As many as 87 percent of these wells were owned by big oil companies, which as per U.S. laws, have the shared responsibility of capping them, even if the ownership of the well changes hands. Exxon Mobil alone could have capped all inactive wells last year and still made a profit of $80 billion.

So, the question really is, why aren't companies capping their wells? It is the enforcement of the laws that need to be tightened, especially if it is going to harm our environment.

Interesting Engineering recently reported that oil and gas production activities had caused excessive deaths and asthmatic attacks in children, leading to health damages of over $77 billion.

The study was published in Nature Energy


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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