Paula Dittrick
OGJ Senior Staff Writer
HOUSTON, July 9 -- BP PLC is likely to start removing the lower marine riser package (LMRP) cap from the runaway Macondo well on July 10, and BP expects the Helix Producer could be collecting oil through a separate floating riser system starting on July 11, an oil spill response official said July 9.
National Incident Commander and retired US Coast Guard Adm. Thad Allen said the LMRP cap will be unbolted and a stub of riser pipe cut off, enabling a new containment cap to be bolted onto a flange to create a seal. Crews will use remotely operated vehicles to do the work.
The LMRP cap has allowed some oil to leak, but Allen believes the next cap will create a seal. There will be a discharge of oil and gas while the LMRP cap is removed and the sealing cap is installed. The sealing cap will function as a valve that can help shut in the runaway well, Allen said.
“Once we completely seal the wellhead, we can determine the most accurate flow rate to date,” Allen told reporters during a news briefing call from New Orleans on July 9. A team of scientists estimates the flow rate at 35,000-60,000 b/d. Allen believes the lower number in the range is the most accurate.
“We want to see how much pressure is inside this cap once we close it off,” Allen said of the sealing containment cap. The reservoir pressure is estimated at 12,000 psi, and Allen anticipates about 9,000 psi will be measured inside the sealing cap. “We do not know to a virtual certainty the status of the wellbore.”
A pressure reading will help drilling crews determine the integrity of the Macondo wellbore. That information will help crews drilling a relief well in preparation for a bottom kill of the Macondo well, operated by BP in 5,000 ft of water on Mississippi Canyon Block 252, Allen said (OGJ Online, July 8, 2010).
An Apr. 20 blowout resulted in a fire and explosion on Transocean Ltd.’s Deepwater Horizon semisubmersible, killing 11 workers. On Apr. 22, the rig sank, and oil spill response crews have been working to stop an ongoing spill. Transocean’s Development Driller III is drilling the first of the two relief wells.
Crews on July 9 continued hooking up the Producer, a floating production unit, with a floating riser collection system. Once installed, the system will have to be tested, and then the Producer will collect an anticipated 20,000-25,000 b/d.
Allen expects the Producer will start receiving oil on July 11, and that the amount it receives will be ramped over during several days. Tropical weather has delayed the Producer’s installation, which Allen originally expected would be finished by July 1.
During the cap replacement procedure on the failed Deepwater Horizon blowout preventer, the Discoverer Enterprise drillship will not be collecting oil and gas.
For the 24 hr ending at midnight July 8, BP collected 24,395 bbl of oil, of which crews flared 8,090 bbl using a special burner on the Helix Q4000 multiservice vessel. Out of the 24,395 total, the Enterprise collected 16,305 bbl. Together, the Enterprise and Q4000 flared 55.5 MMcf of natural gas, BP said.
About 709,100 bbl of oil total has been recovered using both the LMRP Cap and Q4000 systems since they were implemented. Another 22,000 bbl was collected using a riser insertion tube earlier in May, BP reported.
Contact Paula Dittrick at [email protected].
US Government Accountability Office.
