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BP developing more options to halt gulf oil spill

Paula Dittrick
OGJ Senior Staff Writer

HOUSTON, May 13 -- BP PLC said cost of the oil spill response amounted to about $450 million as of May 13, and scientists and engineers from across industry and government continued work to stop an oil spill from a blowout in 5,000 ft of water off Louisiana.

Separately, the International Association of Drilling Contractors (IADC) has requested a reprieve for drilling operations in the shallow-water Gulf of Mexico. Currently, new drilling in the gulf is under an interdiction scheduled to last at least 3 weeks.

BP and other operational experts are developing options to stop the flow of oil from the Macondo well through interventions via the failed blowout preventer (BOP). An estimated 5,000 b/d is leaking into the gulf.

Potential interventions included a “top kill” or “junk shot” of the well, which involves plugging the interior of the BOP with various items and sealing the wellhead by sending heavy fluids and then cement through the BOP’s choke and kill lines (OGJ Online, May 10, 2010).

“Plans for this option are being developed in preparation for potential application next week,” the company said in a May 13 news release about the top kill method.

Transocean Ltd.’s semisubmersible rig, Deepwater Horizon, drilled the well on Mississippi Canyon Block 252. The rig exploded Apr. 20, leaving 11 crew members missing and presumed dead. On Apr. 22, the Deepwater Horizon sank.

BP is the operator with 65% interest. Partners are Anadarko Petroleum Corp., 25%, and Mitsui Oil Exploration Co. Ltd., 10%.

Other separate options being considered to stop the flow include possible installation of a BOP on top of the existing BOP stack or installing another shutoff valve. Previously, a shutoff valve was installed on one leak on the damaged Deepwater Horizon, reducing the number of oil leak sources from three to two.

Containment system options grow
In addition to stopping the flow, BP is working to collect leaking oil. The company is considering two containment options. One is to use a top hat container device that already is sitting on the seabed.

In a related containment option, spill response scientists and engineers are considering the use of a riser insertion tube that would be inserted well into the damaged Deepwater Horizon riser.

Doug Suttles, chief operating officer of BP Exploration & Production, told reporters during a May 12 news conference that all containment-related equipment was being put in place pending a final decision on which containment option would be implemented.

Deployment of a containment system was expected “to be attempted within the next few days,” BP’s May 13 news release said. “All of the techniques being attempted or evaluated to contain the flow of oil on the seabed involve significant uncertainties because they have not been tested in these conditions.”

The riser insertion tube would prevent leaking hydrocarbons from contacting seawater and forming gas hydrates, which was a problem with an earlier large containment dome (OGJ Online, May 10, 2010).

The US Minerals Management Service has approved the use of methanol in conjunction with the top hat to prevent the formation of hydrates.

Warm seawater from the surface would be pumped along the riser bringing the collected oil and gas to the surface for processing and storage on Transocean’s Discoverer Enterprise drillship.

IADC request
IADC said prohibiting new drilling in water depths less than 1,000 ft that use BOPs above the sea surface will unnecessarily cause the loss of thousands of jobs and could spur business insolvencies.

“IADC is seeking an exemption from the drilling ban for this type of operation, as well as a clarification of the rule,” said Lee Hunt, president of IADC. He noted the blowout involves a BOP on the seabed.

“In contrast, drilling in less than 1,000 ft of water using blowout preventers above the sea surface is very different,” he said. “To ban this type of drilling is unnecessary, either to protect human safety or the environment and will put thousands of hard-working people out of work.”

He noted numerous differences between shallow-water drilling and deepwater options.

Deepwater primarily involves oil exploration and development while shallow-water operations involve primarily natural gas.

Oil remaining in shallow-water reservoirs largely has been produced and is underpressured, limiting its ability to spew out of control. In addition, in shallow water, the seabed can be much more easily accessed for intervention by remote craft and even divers, he said.

Typically, wells drilled by jack up drilling rigs in shallow water take 15-40 days. If the current ban were to continue through July 1, IADC estimates that some 60% of gulf rigs could be idled.

“Not only will this present problems for sustained energy supply, it could economically devastate hard-working offshore employees and the economies of coastal Louisiana parishes,” Hunt warned. “It is important not to overreact.”

More hearings scheduled
From Kenner, La., the Marine Board of Investigation reported 13 witnesses testified in hearings May 11-12. Testimony included discussion regarding the search and rescue efforts, accounts of rescuing evacuated crew, and other safety details.

“It is expected that there will be two or three more public proceedings of the joint investigation,” MBI said in a news release. A second public proceeding is scheduled for May 25-29.

MBI is a joint investigation by the MMS and the US Coast Guard into the rig accident and oil spill.

Contact Paula Dittrick at paulad@ogjonline.com.


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