With New Cap in Place, What Now?

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A timeline of the disastrous BP oil spill in the Gulf of Mexico. View the photo gallery

Now that the sealing cap has been installed, all eyes turn to the well integrity test, which BP is starting today, Senior Vice President Kent Wells said at a morning press briefing. The test will involve completely "shutting in" the well so the full pressure of the oil gusher can be measured, giving the scientists and engineers a read on the structural stability of the piping that lines the 13,000-foot-long well. The results of the test will be critically important for determining whether it's safe to leave the well shut in, ending the flow indefinitely, or whether the well will have to be opened up and oil-containment operations resumed to minimize the leaking oil while preventing further damage to the well bore.

Once the test begins, it will take anywhere from six hours to two days. “It is expected, although cannot be assured, that no oil will be released to the ocean for the duration of the test,” said a BP press release. The company further cautioned that lack of oil flow from the well during the course of the test should not be taken as an indication the oil flow has been permanently stopped. "We're going to run the test, and based on that information, we're going to make decisions," Wells said. Both industry and government scientists will be in on the process of evaluating the results.

The installation of the new, tighter-fitting cap was accomplished without a hitch, in contrast to many of BP’s previous, ill-fated efforts. The company had been planning to install the cap over a four- to seven-day period, but the installation was completed Monday evening, only three days into the endeavor.

After removing the old cap, engineers unbolted and detached the cut-off riser pipe from a flange at the top of the blowout preventer and bolted on a new specially designed pipe in its place. They then lowered the 75-ton capping device, called a “three-ram stack,” atop the new pipe and latched it on, completing the installation at 7 p.m. CDT on Monday. The new cap resembles a mini blowout preventer, with hydraulic valves that should be strong enough to hold back the oil flow entirely.

"I couldn't be prouder of the team that put on the cap," Wells said.  Yet he pointed out that this is only one step in the multistep—and highly complex—process of killing the well. "We know that the job’s not over yet," he added.

Before the well-integrity test begins, collection of oil through lines on the blowout preventer will have to be suspended to ensure that the pressure in the well reflects the total oil flow (currently, the Q4000 vessel and the Helix Producer are drawing oil up to the surface from the choke and kill lines of the blowout preventer).

Once the valves on the new cap are closed and the well is shut in, high-pressure readings would be good news, suggesting that the well casing is undamaged and that all of the flow is coming up through the well. In this scenario, it would be possible to keep the well closed off indefinitely, effectively ending the spill (the relief wells would still be completed to permanently seal the well with cement).  Low pressure, on the other hand, would be a bad sign, suggesting that oil is leaking out below ground through damaged sections of the well casing and percolating into the surrounding rock.  In a worst-case scenario, that oil could find its way up to the surface and start an uncontrolled leak from somewhere on the sea floor of the gulf. Either way, a low-pressure result would force engineers to open up the valves and allow oil to flow once more, though BP says it would soon have enough capacity to funnel all of it to the surface for collection.

Paul Bommer, a petroleum engineer at the University of Texas at Austin, says it may not be all or nothing—depending on the results of the pressure test, BP may be able to partially open the well to relieve some pressure without opening it all the way.  This would at least minimize the amount of oil flow that would need to be contained should industry and government scientists decide that keeping the well completely closed in is too risky.

Up till now, it’s been impossible to know for sure what kind of condition the well casing is in, but the integrity test will finally shed some light on this crucial issue.
"Everybody hope and pray that we see high pressures here," Wells said.

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