More than 27,000 abandoned oil and gas wells pervade the Gulf of Mexico, but neither industry nor government has checked the wells for leaks, an Associated Press investigation has found.
Most alarming are 3,500 wells classified by federal records as “temporarily abandoned.” Sealing procedures for temporarily abandoned wells are not as secure as those for permanent closures, and regulations require oil companies to present plans to reuse or close these wells within a year. But the AP investigation found that more than 1,000 wells have been in temporary abandonment for more than a decade.
The BP Deepwater Horizon rig was being temporarily sealed when it exploded on April 20, and BP has abandoned about 600 wells in the Gulf. The oldest wells date back to the late 1940s, and the sealants risk rusting and cracking from decades of sea water exposure.
Both Texas and California have sealed thousands of abandoned wells in state waters, but federal regulators do not inspect abandoned wells in U.S. waters.
Instead, after an oil company reports that it will permanently abandon a well, the U.S. Minerals Management Service relies on paperwork to know that the job is done. No agency actively looks for deep underwater leaks, which are hard to detect from the surface.
A 2001 study commissioned by the minerals service reported concerns that “some abandoned oil wells in the Gulf may be leaking crude oil,” but nothing came of the warning. John Amos, the geologist who wrote the study, told the AP that the minerals service withheld critical information at the time, and refused to tell him “how big and widespread a problem” they were dealing with in the Gulf.
Government regulators and industry officials said abandoned offshore wells are properly plugged and last indefinitely. “Only when pressed do these officials acknowledge the possibility of leaks,” the AP reported.
But even fully depleted wells can reactivate because of fluid and gas injections from nearby wells, or pressure from underlying aquifers, experts say.
Maurice Dusseault, a geologist at the University of Waterloo in Ontario, Canada, says U.S. regulators “assume that once a well is sealed, they’re safe — but that’s not always the case.”
