Could Damaged Oil Well Casing Lead to Underwater Tar Pit?


Updated 5:19 p.m. Eastern Time

Some Congressional investigators who have consulted with a noted scientist are concerned about reports that the Deepwater Horizon oil rig's well casing is damaged.

The fear is "we could end up with the La Brea Tar Pit," said one source, referring to the tar pits in Los Angeles where tar (brea in Spanish) has seeped from the ground for tens of thousands of years.

The belief that the well casing has been damaged comes from anonymous BP officials quoted in news reports as well as a mention from Admiral Thad Allen, the National Incident Commander.

They indicated that drilling mud used in top kill was going off to the side into rock formations. This would mean a breach (or more than one) in the well casing. Allen referred to it as a possible "crack."

According to the Congressional investigators, a breach in the well casing could mean:

  • Like the drilling mud, oil is leaking into rock formations outside the well. If the rock is porous, the oil would eventually bubble up from different spots in the ocean floor (where it may not be seen by us). It's important to know how high up in the well any breach or crack is. The higher it is, the worse the scenario because the closer it is to potentially porous rock and the ocean.
  • The well leak could be significantly worse than what's been measured from the end of the pipe. Picture a garden hose punctured with an ice pick a few feet from the end nozzle. If you only measure the flow coming out of the end nozzle, you're missing what is spurting from the ice pick hole.
  • It may have implications for the relief wells, and could mean it will take longer than three months to plug the leak.

Florida Democratic Sen. Bill Nelson sent a letter Wednesday to BP America President and Chairman Lamar McKay asking him to address the BP official's comments that new damage was discovered in the well during the "top kill" procedure.

"If the sourced information is accurate and mud leaked out the side of the well casing, oil and gas likely are leaking beneath the seafloor as well, according to Professor Ian R. MacDonald, an oceanography expert at Florida State University who advised my staff," he wrote.

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    Sharyl Attkisson is a CBS News investigative correspondent based in Washington.