|
Drilling halted at Thunder Horse BP launches investigation after marine riser separates from drillship Petroleum News Houston Staff
Development drilling at the BP-operated Thunder Horse field, the largest oil discovery in the Gulf Mexico, was suspended after a rare separation of the marine riser from the drillship.
Drilling contractor Transocean said May 23 operations at the 1 billion barrel Thunder Horse field, located in 6,000 feet of water on Mississippi Canyon Block 822, would not resume for at least two to three weeks. An investigation into the cause of the incident has begun, BP said.
“We are taking this very seriously and are in no rush to resume until we figure this out,” a spokesman for the company said.
The marine riser, which houses the drill pipe, parted “somewhere” between Transocean’s drillship Discoverer Enterprise and the wellhead around 4 a.m. on May 21, a spokesman for Transocean said. No injuries, no spills No one was injured and no hydrocarbons were spilled as a result of the riser separation, he said, adding that a visual inspection with a remote-operated vehicle also showed no damaged was done to the wellhead.
But a riser separation is a rarity, both companies said, and that’s one reason “we want to let this investigation run its course,” the Transocean spokesman said. It also will take time to repair the riser, most of which was still hanging from the drill ship, he said.
Two years ago Diamond Offshore reported a parting of a marine riser from its Ocean Baroness semi-submersible drilling rig in 5,700 feet of water offshore Malaysia. The separation occurred around the 2,300-foot level. A preliminary investigation indicated that bolt assemblies had failed at the riser connection. The riser eventually was retrieved and repaired. No delay in field startup BP said the incident at Thunder Horse would not delay field startup in 2005. Transocean was drilling the field’s ninth development well when the riser separated.
Thunder Horse, owned 75 percent by BP and 25 percent by ExxonMobil, is expected to produce about 250,000 barrels per day of oil and 200,000 million cubic feet a day of natural gas.
Transocean is the world’s largest offshore drilling contractor with more than 170 full or partially owned and managed mobile offshore drilling units, inland drilling barges and other industry support assets. The company maintains a fleet of 28 deepwater rigs, including the Discoverer Enterprise.
| 