BP is seven to 10 days away from being in position to intercept its spewing Gulf of Mexico well with a relief well that is considered the best hope for permanently shutting off the flow of oil, National Incident Commander Thad Allen said Thursday. But because drilling the final leg of the relief well requires slow and precise work, Allen said he is sticking to initial estimates that the well will be sealed sometime in mid-August.
The energy company is drilling two relief wells to try to permanently shut down the Macondo well, which has been gushing oil ever since April 20, when the Deepwater Horizon rig exploded and sank in the Gulf of Mexico. The primary relief well, which is being drilled by a rig called the Development Driller III, was at 17,780 feet below the water’s surface Thursday evening. A backup relief well had been drilled to 13,930 feet.
The plan is for the relief well to drill into the damaged well at about 18,000 feet, pumping mud into the damaged well forcefully enough to overcome the flow of oil. Once the flow of oil has been tamped down, cement will be injected into the well to seal it off.
On Thursday, Allen asked BP to provide a “detailed timeline” for the estimated completion of the two relief wells.
BP Chief Managing Director Bob Dudley said this week that in a “perfect case” scenario, the well could be finished by July 27, the same day the company reports its second-quarter earnings.
“In a perfect world with no interruptions, it’s possible to be ready to stop the well between July 20 and July 27,” Dudley said in an article published by the Wall Street Journal.
But BP spokesman Max McGahan said the perfect case Dudley spoke of was unlikely to occur because of weather limitations.
“Essentially, it was very much a hypothetical,” McGahan said of Dudley’s comment. “Realistically, it is very unlikely we’d make that timing for a lot of reasons including weather. The expectation, the target, is still mid-August.”
Allen also called the August date a more attainable target. Engineers are trying to locate the Macondo well by sending out electric currents from the relief well to the damaged well’s casing, a process called ranging. The procedure creates an electromagnetic field between the wells that signals information about direction and distance. The closer the wells get to each other, the stronger the signal becomes, eventually allowing engineers to determine exactly where they should drill.
The process is time-consuming and exact, with drilling going only 10 to 15 feet each time before it is stopped, so the drill pipe can be retracted and tools inserted to conduct the ranging exercise.
The relief well will first penetrate the damaged well’s annulus, an outer casing. If oil is discovered in that area, mud and concrete will be pumped into it, Allen said. The drill will then move into the steel pipe inside the casing and pump mud and cement into it.
How long the process takes will depend on how long it takes to overcome the flow of oil in those areas, Allen said.
Until drilling on the relief well is complete, BP is using a system of containment devices to collect oil as it escapes. Two vessels, the Discoverer Enterprise and the Q4000, make up the current system. The former collects oil for refinement, while the latter flares it off on site.
Together, the vessels collected 24,575 barrels of oil from the spill site Wednesday. An estimated 35,000 to 60,000 barrels of oil are escaping each day.
Plans to introduce a third vessel to the containment system have been delayed for more than a week because the high seas produced by Hurricane Alex and another low pressure system have made connecting it impossible. That vessel, the Helix Producer, has the capacity to collect 25,000 barrels of oil per day, nearly doubling the current capacity.
Allen gave BP 24 hours on Thursday to submit a plan and timeline for hooking the Helix Producer into the containment system and for removing and replacing an ill-fitting cap being used to corral oil at the source of the gusher.
Oil is evading the cap, and BP and administration officials think replacing it with a better-fitting model would allow more oil to be collected. But taking the current cap off and replacing it could take several days in ideal conditions and longer if weather becomes a factor, during which time thousands of barrels of oil that otherwise would have been captured would be released into the sea.
The initial plan was to wait and see whether adding the Helix Producer would capture all of the escaping oil. If it had turned out that the three-ship containment system was capturing all of the oil, the ill-fitting cap might not have been disrupted.
But Allen said Thursday that the weather delay in connecting the Helix made doing that a less attractive option.
In order to consider whether to replace the cap on the well, “I must have knowledge of the steps and decision points involved, mitigation efforts to be implemented, and contingency plans if these efforts are not successful,” Allen said in a letter dated July 8 and addressed to BP’s Dudley.
BP’s response is due today after Allen meets with the Federal Scientific Technical Team in Houston, the letter says.