03 May 2010

Plan C and D to Cap the Leaking Oil Well

"Every time we think we're almost at the end of our options, our engineers keep coming up with new alternatives," BP communications boss John Curry told UpstreamOnline.

"We're not going to quit, that's for sure. We want to get that well stopped and we want to clear that mess up. We'll be judged on how we do that." _Upstream
Here is more information about the ongoing attempts to stem the flow of oil from the Deepwater Horizon well. BP has had some success operating the blowout preventer stack, but the valves have apparently been degraded and cannot stop the flow. While they are preparing the containment vessel, they are preparing to add another blowout preventer to the bore to see if it can slow the spill. They are also working out a plan to install another type of valve to the drill pipe. One relief well is already "spud" or initiated, and a second rig is on the way to the site to drill a second relief well. The relief wells could take up to 3 months to complete.

From Upstream Mag via Bit Tooth Energy:
BP is looking at installing a new BOP on top of the existing well, which could then be used to shut the well, BP executive Bob Fryar said.

Fryar normally heads BP offshore exploration operations in Angola.

Sometime in the next three days, BP will try to install a meter to gauge the pressure on the lower marine riser package (LMRP), which sits on top of the existing BOP, to see if it might be possible to install a new BOP on top.

If pressures are not too high, Fryar said crews could shear off the broken riser and LMRP unit and then "stab" or stack a second BOP unit on top of the original BOP.

The new BOP is already on board the Transocean drillship Discoverer Enterprise, which is believed to be on location.

However, if it does not work it could cause the flow from the well to increase by eliminating the back pressure created by the crimped riser.

Even if the pressure is too high to install a second BOP, the information may help BP make better estimates on the amount of oil coming from the well.

Fryar stood by BP's assertion that the best estimate for the flow is 5000 bpd, but said he also reiterated that the figure had a wide margin of error.

Trigger

Meanwhile, BP will continue trying to close the well with the BOP that is already in place on the sea floor.

It has been one of the main focuses of BP's efforts since the initial blowout and will remain so, no matter how unlikely it is to work, Fryar said, because it offers the quickest way to stem the flow.

Charlie Holt, who heads BP drilling and completions operations in the US Gulf, said BP has repaired some leaks in the hydraulic systems of the BOP.

Since then, BP has been able to trigger all of the six rams that should shear the drill string and casing and close the well, but they did not stem the flow.

Holt said some of the rubber portions of the BOP may have been eroded by sand in the flowback and may not be able to shut the well anymore.

If the second BOP can be added to the well, it may be possible to circulate fluid through that to kill the well, but BP continues with plans to drill a pair of relief wells.

Intercept

The third rig, Development Driller II, will get on location in 10 to 12 days and will "race" to spud a second relief bore.

That rig was working to secure a well on BP Atlantis project on Green Canyon 743, according to MMS data, before setting sail.

Fryar said both rigs were needed in case one ran into problems while drilling and to ensure a relief well is drilled as quickly as possible.

Development Driller II is currently working to secure a well on other BP acreage in the Gulf before setting sail for Macondo.

Meanwhile, BP will try within 24 hours to install a valve on the damaged drill pipe that will allow it to shut in flows coming out of the pipe.

Crews have already sheared the jagged end of the pipe so that there is a smooth cut to attach the valve.

The pipe, which extends beyond the end of the broken riser, is one of three leaks the company has identified.

Though the largest leak by far is at the end of the riser itself, BP said installing the valve on the drilling pipe reduce some of the flow of oil from the well.

Cofferdam

While this flow might be redirected to the main leak at the end of the riser, BP said it hoped to capture much of this oil in a massive cofferdam being rush fabricated for the purpose.

The first of the three giant containment domes, measuring 14 feet by 24 feet by 40 feet, has been completed at a yard in Louisiana and is ready to load onto a work boat.

Fryar said it could be "deployed and in service" over top of the main leak in the next six to eight days.

Once in place, oily water would be trapped under the dome and will be pumped to the Discoverer Enterprise.

Once on board it would be processed and loaded onto a tanker to be brought to shore.

The pipework connections linking the cofferdam to Discoverer Enterprise have been finished.

Work continues on two more cofferdams, one of which is set to go over a smaller leak at the juncture of the riser and the LMRP.

A similar system worked in the shallow water US Gulf after hurricanes damaged production installations but it has never been tested at this water depth, Fryar said.

Fryar also said BP successfully tested a plan to apply dispersant to the oil as it exits the riser two days ago.

Over a six-hour test, BP sprayed about 3000 gallons of dispersant using 2-inch coil tubing connected to a wand.

The dispersants break the oil into smaller portions and allow it to naturally degrade more quickly.

Disaster

Fryar said BP was pleased with the results but that it would take some time before changes in the volume of oil on the surface were noticeable.

BP has been give federal approval to continue the practice and began applying subsea dispersants again today.

The company now plans to try to drill into the riser and directly inject dispersant into the oil stream before it shoots into the water.

The direct injection would ensure that more dispersant comes in contact with the oil and would give the substances a chance to fully mix before being diluted by water.

Fryar said BP hopes to try the direct injection sometime "over the next several days".

...In addition, the UK supermajor has mobilised a third drilling vessel, the Transocean semi-submersible rig Development Driller II, to spud a second relief well.

_Upstream

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