GULF OF MEXICO — Crews are expected to begin drilling a relief well Thursday at the site of a gas well that blew wild July 23 off the Louisiana coast but eventually was choked off by sand and sediment.
The federal Bureau of Safety and Environmental Enforcement said the Rowan EXL-3 rig has been moved to the site, about 55 miles southwest of Grand Isle, and will drill the relief well under contract to well owner Walter Oil & Gas Co.
The work to drill into and then plug the well with mud and cement is expected to take about 35 days.
BSEE has opened an investigation into the cause of the blowout, working with the Coast Guard. Investigators are expected to examine the blowout preventer, which apparently failed.
The Hercules 265 rig, owned by Houston-based Hercules Offshore, was drilling at the site on July 23 when the well blew out. All 44 workers aboard the rig were safely evacuated, but natural gas spewing from the above-water wellhead later caught fire.
The fire was extinguished the next day when sand and sediment naturally plugged the well hole, shutting off the flow of gas.
A small amount of oil also was discharged after the blowout, producing a sheen that appeared and then quickly dissipated several times.
BSEE spokeswoman Eileen Angelico said Tuesday that a sheen is no longer visible on the surface of the Gulf of Mexico.
Authorities had not expected an environmental disaster similar to the massive BP crude oil spill, in part because the Walter well was discharging mostly gas and because it’s location was in relatively shallow water — 154 feet — making it easier to deal with.
BP’s Macondo well was about 5,000 feet below the Gulf’s surface. It created the nation’s worst offshore oil spill as an estimated 200 million gallons of oil spewed before the well was brought under control months after the April 2010 blowout.