OGJ Senior Staff Writer
HOUSTON, May 10 -- BP PLC executives plan to attempt to contain the oil spill in the Gulf of Mexico using a small containment structure, which they are calling a top hat. Meanwhile, they also plan to stop the flow of oil from the deepwater well off Louisiana by plugging up the blowout preventer in 5,000 ft of water and then sealing the wellhead.
BP Group Chief Executive Tony Hayward met with reporters May 10 at BP’s offices in Houston where he said hundreds of technical experts and operating specialists from various companies and countries are working on multiple options in parallel.
“We continue to fight this very aggressively,” Hayward said. “We are learning all the time. A lot of real-time learning is going on…. The learning from this will be very extensive.”
Earlier on May 10, BP announced it has spent $350 million on spill response efforts at the ocean’s surface, subsea containment efforts, relief well drilling, and payments to Louisiana, Alabama, Mississippi, and Florida.
BP and partners hired Transocean Ltd.’s semisubmersible rig, Deepwater Horizon, to drill the Macondo well on Mississippi Canyon Block 252. The Deepwater Horizon exploded Apr. 20, leaving 11 crew members missing and presumed dead. On Apr. 22, the Deepwater Horizon sank.
The oil and gas well is spilling an estimated 5,000 b/d. BP is the operator with 65% interest. Partners are Anadarko Petroleum Corp., 25%, and Mitsui Oil Exploration Co. Ltd., 10%.
Top hat technique
On May 9, BP set aside a large containment dome that it had hoped to place over a damaged, leaking riser on the seabed because gas hydrates built up in the dome. Engineers had hoped the 98-ton dome could capture an estimated 85% of the leaking oil and gas, which then was to be pumped to a drillship on the surface.
“We learned primarily that there is a lot more gas involved in this leak than we had believed,” Hayward said.
BP plans in 72 hr to deploy a small containment structure called a top hat, Hayward said. The idea behind the smaller top hat is to prevent the leaking oil and gas from contacting the sea water, which is 30° F. at 5,000 ft.
Hayward said engineers believe the amount of sea water in the large dome contributed to the formation of more gas hydrates than engineers had expected even though they had anticipated that gas hydrates could be a problem.
Methanol to prevent the formation of gas hydrates also will be used in conjunction with the top hat, which is about 4 ft by 5 ft, Hayward said. BP has necessary approvals from federal officials to use the methanol.
Previously, BP planned to place the containment dome over the damaged riser and then to connect a riser from the containment dome to the drillship. In the top hat method, BP plans to connect the riser to the top hat before the top hat is put in place on the seabed.
“It will be a little trickier for us, but we will make it work,” Kent Wells, BP senior vice-president of exploration and production, said of the top hat method vs. the larger dome. “There are always some pros and cons to everything we try.”
He said some pipes will be placed into the seafloor to help secure the top hat.
Top kill technique
In what is known as a “top kill” or a “junk shot,” BP plans to first plug up the BOP by shooting various items including cut-up tires, ropes with knots, and golf balls into the internal workings of the BOP to seal it.
A pipe from the surface will be hooked to the BOP so that junk can be shot inside it. “We can give this several shots,” if needed, Wells said. “The No. 1 priority is to shut off the flow of oil.”
Immediately upon plugging the inside of the BOP, then BP plans to use existing choke and kill lines running along the BOP to send heavy fluid or mud at high pressure into the wellhead to push the oil and gas back into the reservoir. Eventually, cement will be sent into the well to seal and permanently abandon the well.
In describing the technique to reporters, Wells noted many unknowns exist. “We’ve never had a blowout before at 5,000 ft.”
Previously, BP used remotely operated vehicles to retrieve the control pod from the BOP. The control pod’s electronics are being refurbished to send electric signals to the choke and kill lines on the BOP stack. Wells said he hopes the junk shot can be done in 2 weeks.
“Whatever we try, we want to make sure it’s not going to make things worse,” Wells said. “We really believe it’s going to plug up the BOP. There are a lot of different steps to do. We will put whatever pressure it takes into the well,” to stop the flow of oil and gas.
Meanwhile, one relief well is being drilled, and a second relief well will be drilled as a backup to the first relief well in case the first relief well were to run into problems.
Drilling of the first relief well started May 2 and is expected to take up to 90 days. It had reached 9,000 ft of its total 18,000 ft as of May 10, Hayward said. Drilling of the second relief well was scheduled to start on May 14.
In other spill response efforts, BP is applying chemical dispersants on the subsea oil leaks to help break up the oil so that it can degrade before reaching the surface. Meanwhile, controlled burns are being done on open water to eliminate some of the oil slick before it reaches shore.
Skimming vessels and booms also are being used to prevent much of the oil from reaching shore. Airplanes also are spraying chemical dispersants on oil after it reaches the water’s surface. Oil has been reported reaching the shore in Louisiana and Alabama.
Joint USCG-MMS investigation hearing
The US Coast Guard and Minerals Management Service scheduled a 2-day public hearing starting May 11 in Kenner, La. The hearing concerns a joint investigation by USCG and MMS to identify factors leading to the rig accident and subsequent oil spill.
USCG Commandant Adm. Thad W. Allen, MMS Director S. Elizabeth Birnbaum, Department of Homeland Security Secretary Janet Napolitano, and Department of the Interior Secretary Ken Salazar signed an order convening the joint investigation, which is classified as a Coast Guard Marine Board of Investigation.
USCG and MMS share jurisdiction for the investigation of casualties occurring on the Outer Continental Shelf. Upon completion of the joint investigation, the team will issue a single report simultaneously to both agencies.
Other congressional hearings and investigations into the cause of the accident and spill are going on this week in Washington, DC.
Contact Paula Dittrick at firstname.lastname@example.org.