10 May 2010 22:23 [Source: ICIS news]
HOUSTON (ICIS news)--The US Environmental Protection Agency (EPA) has given BP permission to use methanol to prevent the formation of crystalised gas hydrates in its efforts to stop the oil leak in the US Gulf of Mexico, the company’s chief executive said on Monday.
BP was unsuccessful last week in its attempt to contain the underwater leak with a 40-foot-tall (12-metre) steel and concrete vault when crystalised gas hydrates formed inside the container, plugging the top where the oil would have been siphoned out.
BP now planned to use a much smaller container to put over the leak, which was roughly 5,000 feet under water.
Methanol would be pumped to the container to prevent the freezing that clogged pipes of the larger box, CEO Tony Hayward said.
Methanol is frequently used as a de-icer.
“The rationale for a smaller dome is there will be less sea water in the smaller dome, and thus less likely to have hydrate formation,” ?xml:namespace>
The smaller container was 5-feet-tall with a 4-foot diameter, or about the size of a barrel of oil cut in half,
Temperatures at the subsea level, where the BP-operated Deepwater Horizon offshore rig sank following its 20 April explosion, were about 30°F (-1°C), company officials estimated.
“This is the first time the industry has had to confront this at this water depth,”
The situation was complicated by the presence of a higher gas-to-oil ratio than expected, the company said.
“There was a lot more gas involved than we had been led to believe,”
The smaller container would be launched by Thursday at the latest, BP said.
Immediately after, the company would send a “junk shot” of materials - including golf balls, tyre pieces, rope knots and cement - into the pipe, in hopes of sealing off the flow.
Should that not be successful, the next course of action - which would likely follow next week - would include BP cutting the riser pipe that extended from the well and replacing it with larger piping. That piping would bring the oil to a ship at the surface, the company said.
“We’re working on multiple options simultaneously,” said Kent Wells, senior vice president in BP’s exploration and production business. “We are always planning for if [one option] is failing.”
BP also praised the performance of chemical dispersants used both at the surface and at the sub-sea level at breaking up and dispersing accumulations of oil.
The company said on Monday that it had received
On a longer-term basis, BP said it would begin drilling the second of two relief wells on Friday, a project expected to take 90 days but once completed was certain to permanently stop the oil flow, according to the company.
“The relief wells will ultimately be successful,”
Construction of the first relief well began last week, and the second would serve as a backup in case all areas were not contained in the initial attempt,
About 5,000 bbl/day (210,000 gal/day) of oil has leaked since the 20 April explosion, according to US estimates. The company estimated on Monday that cleanup costs had already reached $350m (€273m).
($1 = €0.78)
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