BP Plans to Seal Damaged Oil Well This Weekend
HOUSTON, Texas, September 10, 2010 (ENS) – This weekend BP expects to re-start the relief well operations that will finally kill the troublesome Deepwater Horizon well that spilled more than 4.1 million barrels of crude oil into the Gulf of Mexico.
The well has been shut-in since July 15 when BP installed a stack of valves that capped the flow of oil and gas.
Since then the company has raised the capping stack and the failed blow-out preventer, a five-story tall, 300-ton set of valves that was supposed to prevent the hydrocarbon leak that resulted in the April 20 explosion and subsequent 87 day-long oil spill.
These pieces of equipment are being held at a NASA facility in Louisiana and will be analyzed for evidence that will enable investigators to understand why a bubble of methane gas escaped from the well and shot up the drill column before igniting.
The failed blow-out preventer is raised from the Deepwater Horizon wellhead. September 4, 2010 (Photo courtesy U.S. Coast Guard)
BP said today that preparations are nearly complete for the final sealing of the wellhead called the “bottom kill.”
A new blow-out preventer has been installed to ensure to oil does not leak from the well during the bottom kill operation.
Following the completion of cementing operations on the well on August 5, pressure testing was performed which indicated there is an effective cement plug in the casing.
A number of diagnostic operations to further understand the well’s condition have been successfully completed, the company said in a statement today. These tests were conducted at the direction of National Incident Commander retired U.S. Coast Guard Admiral Thad Allen.
One test was conducted on the casing hanger – a piece of equipment at the top of the well head that holds the casings that are dropped down into the well bore.
Allen explained that engineers and scientists have been discussing for weeks whether a seal in the casing hanger might open up if it were to be subjected to enough pressure during the bottom kill operation.
To determine the condition of the casing hangar, at Allen’s direction BP today conducted a lead block impression test.
“The test, which uses soft lead metal to form an impression of the casing hangar, shows that the hangar was in the proper location and had not lifted,” BP said.
The next operation to be performed is the installation of a lock down sleeve – a mechanical device that completely secures the casing hangar and the annulus – the space between the drill pipe and the casing.
This operation is a key final step before the company can restart drilling of the relief well.
Admiral Allen said today, “It appears that we can put a device over the top of the wellhead that basically locks it down. That means that entire casing hanger cannot be lifted up and, therefore, allow any free communication between the annulus and blowout preventer.”
“That, in effect, would substitute for our need to be able to cement at the top of the cement plug that’s already there and the annulus,” Admiral Allen explained. “It will allow us to proceed with the relief well more quickly.”
Once the lock down sleeve is installed and tested, BP said it will re-start the relief well operations on the weekend in order to intercept the well annulus.
That interception will allow a drill ship on the surface, nearly a mile above the wellhead, to pump mud and cement into the annulus from the bottom, completing the bottom kill.
Admiral Allen said he could not give an exact time when that process would be complete.
BP began drilling the relief well on May 2 and also began drilling a second relief well to serve as a backup in case of trouble with the first one.
The drill bit on the original relief well has been positioned close to the damaged well head for weeks, but drilling engineers had to wait for the capping stack to be raised and the failed blow-out preventer to be replaced before they could proceed.
Meanwhile, since no new oil has entered gulf waters since July 15, miles of boom laid to protect shorelines has been removed.
“We continue to remove boom where it’s no longer needed,” said Allen. “In Louisiana, Florida, Alabama, and Mississippi we have no boom at this point.”
Allen said the incident response team now is looking at what to do with the extensive field infrastructure that has been deployed in Mobile, Alabama and Houma, Louisiana.
“As we look to finish up the recovery and move to long-term restoration,” the admiral said, the team is “making sure that we have enough response capability to deal with any residual oil that may be found out there and deal with the oil that’s continuing to be recovered in the marsh areas of Louisiana.”