BP plc began injectivity testing at about 1 p.m. CDT Tuesday and then began static kill operations to rein in its runaway Macondo well in the Gulf of Mexico, the source of the world's largest accidental oil spill.

"All operations are being carried out with the guidance and approval of the National Incident Commander," the company said earlier in the day Tuesday before the static kill began. "The aim of these procedures is to assist with the strategy to kill and isolate the well and will complement the upcoming relief well operation."

The static kill, which entails pumping heavy drilling mud and then cement into the well, could take up to two and a half days to complete.

On Monday the government released new estimates for the amount of oil that flowed from the well following the blowout of the well on April 20 and subsequent sinking of he Deepwater Horizon drilling rig. According to the latest government figures, almost five million bbl oil oil leaked from the Macondo well before it was temporarily capped on July 15 (see Daily GPI, July 16).

The Macondo well has surpassed the 1979 blowout of the Ixtoc well in the Bay of Campeche, previously the world's worst accidental oil spill at three million bbl.

The relief well remains the ultimate solution to kill and permanently cement the well, BP said. The first relief well, which started May 2, has set its final 9 7/8-inch casing. Operations on the relief wells are suspended during static kill operations. Depending upon weather conditions, mid-August is the current estimate of the most likely date by which the first relief well will intercept the Macondo well annulus and kill and cement operations will be commenced.

©Copyright 2010 Intelligence Press Inc. All rights reserved. The preceding news report may not be republished or redistributed, in whole or in part, in any form, without prior written consent of Intelligence Press, Inc.