How the "top kill" should work

The idea of a top kill is to overcome the pressure of oil flowing out of the well by pumping heavier drilling mud down into it.

SOURCE: BP; Paul Bommer, professor of petroleum engineering at the University of Texas at Austin | Bonnie Berkowitz and Alberto Cuadra,

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BP poised for 'top kill' to try to plug spill; final decision to come Wednesday

BP About to Take its Best Shot at Shutting Massive Oil Leak 

 

BP About to Take its Best Shot at Shutting Massive Oil Leak

Thirty-six days after the Deepwater Horizon exploded, killing 11 crew members and setting off a massive oil leak, BP may finally be ready to attempt to seal the drill site with a “top kill” of heavy mud followed by cement.

I’ve seen estimates of success at 60 to 70 percent, so keep your fingers crossed.

All of them. It’s a critical moment, the last best chance to stop the flow for weeks if not months. If this doesn’t work…

Here’s how BP describes the process:

“A total of 50,000 barrels of mud will be on location to kill the well – far more than necessary, but we want to be prepared for anything. Pumping capacity on location is more than 30,000 hydraulic horsepower.

The mud will be pumped down the 6-5/8 inch drill pipe (pipe is connected to the Q4000), then through 3-inch hoses, which go through the manifold on the seafloor. Then the mud moves through another set of 3-inch hoses attached to the Deepwater Horizon BOP choke and kill lines.

With the manifold, we can also pump the ‘junk shot’ if necessary to stop too much of the kill mud going out through the top of the BOP rather than going down into the well to stop the flow. By switching valves in the subsea manifold, we can inject the ‘bridging material’ (the junk), which will prevent such losses and enable the top kill to continue.

We’ve been testing the junk shot on-shore, looking at different configurations of what might restrict the flow out of the Deepwater Horizon riser and what types of materials would help shut it off. Materials in a junk shot can include well-known items such as pieces of tires, golf balls, and pieces of rope.”

After initialing declaring that public access to the video feed would be halted during the operation, BP relented last night and announced the feed would continue. It warned:

“Throughout the extended top kill procedure – which may take up to two days to complete – very significant changes in the appearance of the flows at the seabed may be expected. These will not provide a reliable indicator of the overall progress, or success or failure, of the top kill operation as a whole. BP will report on the progress of the operation as appropriate and on its outcome when complete.”

BP had suggested the operation could begin as early as dawn today, but as of 7:30 a.m., there is no indication from the video that operations had actually begun.

On Thursday, Interior Department officials are expected to deliver the results of a 30-day review of the offshore drilling program to President Obama, including recommendations for how tighten oversight. The next day, Obama is scheduled to visit the Gulf.

Congress has also been investigating, as The New York Times reports:

In the hours before the Deepwater Horizon oil rig exploded last month in the Gulf of Mexico, there were strong warning signs that something was terribly wrong with the well, according to a Congressional committee that was briefed on the accident by executives from BP.

Among the red flags, the panel said, were several equipment readings suggesting that gas was bubbling into the well, a potential sign of an impending blowout. Investigators also noted “other events in the 24 hours before the explosion that require further inquiry,” including a critical decision to replace heavy mud in the pipe rising from the seabed with seawater, possibly increasing the risk of an explosion.

…. Some of those who survived the explosion, including managers from BP and Transocean, are expected to testify at hearings in Louisiana to be held by the Coast Guard and the federal Minerals Management Service, beginning Wednesday.

The testimony may help clear up some of the uncertainties about the day of the accident, including who was making the decisions. But the new information from BP — combined with past testimony by executives, analysis of documents by The New York Times and interviews with independent drilling experts — is beginning to paint a picture of a complex operation that went awry just as it was drawing to a close.

Drilling logs from the Deepwater Horizon suggest that shortly after midnight on the morning of the explosion, attention had turned to temporarily plugging and capping the well so the rig could disconnect and move to another job. Halliburton, the contractor hired by BP to provide cementing services, had spent the past several weeks cementing each new segment of the well into place. Halliburton was also responsible for plugging it….

However, in testimony before Congressional hearings, Halliburton executives have said that the company adhered strictly to the specifications provided by BP for the cementing of the well.”

The only break we’ve seemed to get in this whole tragedy has been with the weather. NOAA predicts that it will continue to be calm, for the most part keeping the oil offshore, although portions of the Louisiana coast have already been hammered. Bad as it is, the only solace is that it could be much much worse.

Like I said, keep your fingers crossed, and pray.

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BP poised for 'top kill' to try to plug spill; final decision to come Wednesday

How the "top kill" should work 

Top Kill

BP poised for 'top kill' to try to plug spill; final decision to come Wednesday

The most critical moment in the oil spill crisis in the Gulf of Mexico is at hand, as BP engineers armed with 50,000 barrels of dense mud and a fleet of robotic submarines are poised to attempt a "top kill" maneuver to plug the gushing well a mile below the surface.

It's far from a sure bet.

"It has been done successfully in the past, but it hasn't been done at this depth," Kent Wells, the oil company's senior vice president of exploration and production, told reporters in a conference call Tuesday.

This will be the first stab at shutting down the well since the April 20 blowout and fire that killed 11 workers on the drilling rig Deepwater Horizon.

BP chief executive Tony Hayward told CNN Wednesday morning that the company is still collecting data to determine whether to proceed with the maneuver. "We'll take a decision within the course of today," Hayward said.

If he determines that it is safe to proceed, Hayward told NBC's "Today" show, the procedure is expected to happen Wednesday.

Efforts to capture the spewing oil in the five weeks since the spill have had limited success. The expanding slick has ridden a steady sea breeze onto 70 miles of Louisiana's shoreline and into shellfish-rich estuaries. The sight of oil-soaked brown pelicans is now common. Sticky rust-brown oil slathers the grass in the marshlands. Federal officials closed more fishing grounds Tuesday, bringing the total to more than 54,000 square miles, nearly a quarter of the federal waters in the gulf.

Oil company executives will be grilled in federal hearings resuming Wednesday in a hotel in suburban New Orleans. Later this week, Interior Secretary Ken Salazar is set to deliver a safety review of offshore drilling to President Obama. And then Obama will fly to the gulf on Friday for his second visit to the region since the crisis began. "Like everybody, he's frustrated," Carol Browner, assistant to the president for energy and climate change, told CNN.

The developments on shore may be overshadowed by what happens in the hours and days ahead in the deep water, where the only light comes from the lamps of the robotic submarines. BP's top-kill plan has been devised over more than a month by what BP calls a dream team of engineers from the oil industry and from such government agencies as the Energy Department, the Minerals Management Service and the U.S. Geological Survey. BP has also logged 17,000 suggestions from outsiders, Wells said.



Huge ships and drilling rigs now crowd the surface 5,000 feet above the blown-out well. Two rigs are drilling relief wells but are not expected to complete their work until August. Parked in the middle of everything is the command vessel for the top-kill operation, the 312-foot Helix Q4000. Close by will be the 381-foot HOS Centerline, one of the largest supply ships in the world, capable of pumping 50 barrels of mud a minute. Two other backup ships carrying mud will be nearby.

All the work at depth is performed by the remotely operated vehicles (ROVs), numbering 12 by latest count, and operated from the surface ships while BP engineers monitor the process from Houston. The ROVs have tinkered with the five-story blowout preventer that sits atop the wellhead. They fixed a leaking hydraulic line, for example, using an ordinary wrench pinched by a robotic arm. They also removed the "yellow pod," the brain of the blowout preventer, and engineers repaired it at the surface before replacing it at depth.

On Tuesday, BP engineers began diagnostic tests on the blowout preventer. This is a critical phase in which the company will learn how much pressure must be overcome when the drilling mud is injected into the well. It could also lead them to abort the maneuver.

"We've got a crack team of experts that are going to pore over the diagnostic data," Wells said. "There is a remote possibility that we would get some information that it wouldn't work."

If all goes as planned, a 30,000-horsepower engine aboard the HOS Centerline will pump mud at 40 to 50 barrels a minute to the Q4000 command vessel, then down a newly installed pipe to the gulf bottom, and then through flexible hoses into multiple portals in the blowout preventer.

What happens next would be all-important. The mud would have to go somewhere. The hope is that so much of it would be forced into the preventer that, even as some of it surged up the riser pipe and into the water along with oil and gas, much of it would go to the bottom of the well. The well would lose all pressure and would become static. Later, BP would inject cement down the wellbore to permanently seal the well.

"We know we'll lose some [mud] out the top, but can we pump fast enough to ultimately kill the well?" Wells said. He said the goal is to "outrun the well."

The danger is that the top kill could worsen the situation. The powerful injection of mud might destabilize the blowout preventer, or punch a bigger hole in the sharp kink in the riser just a few feet above the blowout preventer. If the mud doesn't beat back the spill, that could mean a mess of mud mixed with a larger flow of oil and gas.

Greg McCormack, director of the Petroleum Extension Service at the University of Texas at Austin, said he's cautiously optimistic that the top kill will work, saying: "There's always a trade-off between making it better and making it worse. This probably has the least amount of risk of making it worse."

After a protest from Rep. Edward J. Markey (D-Mass.) and discussions with Coast Guard Adm. Thad W. Allen, BP said Tuesday that it will continue to provide live video feed from the sea floor during the top-kill attempt.

The exact timing and pace of the maneuver have not been set, but Wells said the mud injection will begin no sooner than Wednesday. He cautioned that it could take two days to seal the well.

He also gave details for the first time of another backup plan. The top of the blowout preventer would be severed using the robotic submarines. That would temporarily increase the flow of oil into the gulf by 5 to 15 percent, Wells estimated. Then a specially configured containment dome would be lowered onto the blowout preventer. Ideally it would capture much more of the oil than has been contained so far with a small pipe in the end of the leaking riser, he said. That insertion tool has captured an average of 2,000 barrels a day, Wells said, but the well is leaking many times that amount.

The new containment dome could be lowered within a few days if the top kill fails, he said.

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BP about to take its best shot at shutting massive oil leak

How the "top kill" should work