BP PLC and federal officials delayed an integrity test on the runaway Macondo well in the Gulf of Mexico for 24 hr, saying they needed time for analysis before trying to shut in the well on Mississippi Canyon Block 252.
National Incident Commander and retired US Coast Guard Adm. Thad Allen announced the delay late July 13, saying additional analysis of the well testing procedure "should be performed before starting the well integrity test."
US Energy Secretary Steven Chu was in Houston to oversee the well integrity test.
Kent Wells, BP senior vice-president of exploration and production, told reporters that the test might start sometime on July 15.
Wells said the delay was prompted by debate by scientists and industry experts about how to interpret pressure readings during the course of the integrity test, which could take at least 6-48 hr. A leak in a choke line and hub caused yet another delay in test preparations.
"We are trying to understand what pressure readings mean over time," Wells told reporters during a July 14 briefing call. The ideal scenario would be for pressure to build quickly to 9,000 psi once the well was shut in and to hold at that level (OGJ Online, July 13, 2010).
BP wants to avoid a scenario in which oil would be pushed out of the well into shallow zones and leak into the gulf, Wells said.
If the pressure readings were to reach 6,000 psi or less, Allen said the test would be abandoned. Speaking to reporters during a July 13 briefing, Allen said difficulty in interpreting the meaning of the pressure readings could come if the pressure were to stall within the range of 6,000-8,000 psi.
Wells said the pressure readings would be taken by transducers that would not be visible in ongoing video taken by remotely operated vehicles and posted on the BP web site.
Sealing cap installed
The well integrity test was made possible after BP finished installing a sealing cap July 12. A seismic survey was performed July 13 to get baseline information before the well integrity test, Wells said.
The sealing cap consists of a three-ram stack sitting on top of a transition spool, which is a connecting device with a riser flange. The sealing cap replaced a lower marine riser package cap that had been used to collect oil and gas.
"It is expected, although cannot be assured, that no oil will be released to the ocean for the duration of the test," BP said. "This will not however be an indication that flow from the wellbore has been permanently stopped."
Depending upon the integrity test, future options include reinstatement of oil and gas collection systems. Another LMRP cap was available on the seabed for future oil and gas collection efforts.
As OGJ went to press last week, the possibility existed that the flow from the well might be contained with the sealing cap although Wells emphasized the need to evaluate the results of the well integrity test before BP and federal officials determine their next move.
"If the test confirms we can shut in the well, then the well would remain shut in, but it's important to get the test results," Wells said.
Relief wells on hold
Wells said the first relief well, being drilled by the Development Driller III, was at 17,840 ft measured depth on July 14, and drilling operations had been paused for the well integrity test. The well was 4 ft horizontally from the Macondo well.
Operations on a relief well being drilled by the Development Driller II were suspended at 15,963 ft to ensure no interference with the first relief well.
"The relief wells remain the sole means to permanently seal and isolate the well," BP said in a news release.
Pending start of the well integrity test, BP continued to ramp up collection operations on the Helix Producer floating producer unit and also continued to use the Helix Q4000 multiservice vessel, which burns oil using a special burner.
The Helix Producer, with capacity to collect 20,000–25,000 b/d, collected 9,200 b/d for the 24 hr ending at midnight on July 13. The Q4000 flares an average of 8,000 b/d.
"The sealing cap system, the Q4000 system, the flexible riser system, and the planned additional containment systems never before have been deployed at these depths or under these conditions, and their efficiency and ability to contain or flare the oil and gas cannot be assured," BP said in a news release.
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