OGJ Senior Staff Writer
HOUSTON, Apr. 28 -- Oil spill response officials worked to ignite a controlled burn to remove oil from open water off Louisiana following the explosion, fire, and sinking of the Transocean Ltd. Deepwater Horizon semisubmersible rig.
Officials scheduled a controlled burn to start at 11 a.m. Apr. 28 as a way to minimize environmental risks of the oil reaching the coast. On Apr. 27, the leading edge of the spilled oil was 20 miles from Venice, La.
The light, sweet oil is 35º gravity, said BP PLC, which is spending an estimated $6 million/day on the spill response. The Deepwater Horizon was on contract for BP Exploration & Production Inc. to drill the Macondo well, which struck oil and associated gas at a total depth of more than 18,000 ft on Mississippi Canyon Block 252.
The well and nearby vicinity is estimated to be leaking 1,000 b/d. BP and Transocean continued various subsurface wellhead intervention operations to stop the flow of oil. Details on those efforts were expected to be discussed during a 3 p.m. news conference.
Workboats consolidated oil into a 500-ft fire-resistant boom. The boom and oil then was to be towed to a more remote area and ignited. Plans called for small, controlled burns of several thousand gallons of oil with each burn expected to last 1 hr.
The Apr. 20 Deepwater Horizon accident left 11 crew members missing and presumed dead while the semi drilled about 52 miles southeast of Venice, in 4,992 ft of water near Rigel gas field. Cause of the accident remains undetermined and is under investigation.
No populated areas were expected to be affected by the controlled burn operations, and there are no anticipated impacts to marine mammals and sea turtles, the US Coast Guard said.
Ed Overton, a Louisiana State University professor emeritus of environmental sciences, told OGJ that it will be take time before the effectiveness of the burn can be determined. He said the process of igniting the emulsified oil was not easy, adding he had worked in a laboratory with a spill sample, which he described as difficult to ignite.
Most of the oil spill is described as a rainbow sheen, which is a thin mixture of oil and water with most of it being water. Overton said the spilled oil needs to be 0.25-in. thick before it can be burned.
The US Environmental Protection Agency planned to continuously monitor air quality and burning was to be halted if safety standards cannot be maintained.
The Minerals Management Service contacted the oil and gas operators in the sheen area to discuss any concerns with operations that may arise from their activities with the response efforts under way.
No production has been curtailed as a result of the response activities, officials reported.
The vast majority of the slick was expected to be addressed through natural means and through use of chemical dispersants, a response team news release said. Meanwhile, response teams continued skimming operations and applying dispersants.
Preparations are also under way in Louisiana, Mississippi, Florida, and Alabama to set up a protective boom to minimize any shoreline contamination if the oil reaches land.
USCG said 56,000 gal of oil dispersant had been applied as of early Apr. 28 and about 260,000 gal of oily water collected. Nearly 50 vessels—including 16 skimming boats, 4 storage barges, and 11 support vessels—and multiple aircraft are involved in the containment and cleanup operations.
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Officials use a controlled burn for oil spill in gulf