Mud continues to hold oil under blown-out well, BP says | Environment| All topics from climate change to conservation | DW | 04.08.2010
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Mud continues to hold oil under blown-out well, BP says

BP said it reached a "milestone" in keeping more oil from gushing into the Gulf of Mexico. The spill is now the largest in history, but experts are expected to show that its impact will be less than some feared.

Vessels involved in the static kill operation in the Gulf of Mexico

BP's latest effort seems to have plugged the spill

Following eight hours of pumping mud into its blown oil well, BP announced on Wednesday that the well has reached a static condition. The company began the pumping operation known as a "static kill" on Tuesday.

A static condition signals a state where pressure from the mud stops the leak by offsetting pressure in the reservoir that causes the oil to shoot to the surface. Tuesday's maneuver was an alternative to the company's failed attempt to install a valve over the well to stem the gushing oil.

"A static situation basically means you can have just fluid in the hole, and you don't need to have a valve shut at the surface to have the well killed," said BP Senior Vice President Kent Wells at a press conference on Tuesday.

The company's next and final step in killing the well involves pumping cement into the site. In the coming days, the company will monitor the well in order to decide whether to begin pumping cement immediately or wait until mid-August when drilling on the first relief well is expected to be completed.

The "static kill" would take 33 to 61 hours to complete, officials said before Wednesday's announcement.

Not until cement has been successfully pumped in and the relief wells are finished can the well be considered fully closed, according to US Coast Guard Admiral Thad Allen, who has headed the government's response to the spill.

Not regular mud

Drilling mud escapes from a pipe in an underwater image from BP

Drilling mud has a thick, pasty consistency in this BP image capture

Unlike regular mud, the mud pumped into the well is itself a feat of engineering.

"The mud is a very complex fluid that was assembled by experts in a laboratory," said Matthias Reich, director of the Institute for Drilling Procedure and Liquid Mining at the Technical University of Mining in Freiberg. "It has a pasty consistency and, in this case, is very heavy."

The drilling mud was used in multiple tests that paved the way for Tuesday's static kill operation.

Less damage than initially feared

The Deepwater Horizon oil spill now ranks as the biggest marine spill in history will an estimated 4.9 million barrels of oil (around 200 million gallons, 757 million liters) released into the Gulf of Mexico since the rig's explosion on April 22. The spill is followed by 1979's Ixtoc-1, also in the Gulf of Mexico, in which around 3.3 million barrels of oil erupted.

An oil tanker photographed from above

The Deepwater Horizon spill now ranks as the largest in history

Nevertheless, a US government report is expected to be revealed later on Wednesday with data that shows the impact of the spill is far less than feared.

The National Oceanic and Atmospheric Administration is the leading agency responsible for the report that is expected to claim that just 26 percent of the oil that erupted from the site exists in an environmentally dangerous form.

The report is also expected to show that sizable quantities of the oil have evaporated at the water surface or have otherwise dissolved into the water with limited ecological consequences.

Author: Greg Wiser (dpa, Reuters, AFP)
Editor: Sean Sinico

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