By Steven Mufson
Washington Post Staff Writer
Wednesday, May 26, 2010; 7:59 PM
BP's head of safety and operations Mark Bly and other company officials gave reporters a technical briefing Wednesday on what BP's internal investigation of the accident had learned so far, pointing to a cascade of breakdowns and mistakes. New details included:
-- BP's chief representative was "present" on the rig during a discussion of an abnormal increase in pressure in the drill pipe, an indication that gas was probably in the pipe when it shouldn't have been. That representative never called the Houston office for advice, despite the indications of trouble and differences between him and the top Transocean person there.
-- People on the rig should have known there was oil or gas in the drill pipe because when they were replacing drilling mud with seawater they only needed 352 barrels instead of 775 barrels.
-- Pressure logs that were sent to BP's Houston office via Halliburton suggested that rig workers tried to close valves on the blowout preventer at least twice in the final 18 minutes before the explosion that sank the rig. It remains unclear why that did not work. After the explosion, other efforts to activate the blowout preventer also failed.
-- Earlier, BP officials on the rig and in Houston decided to run only six tests instead of 21 tests they originally planned to make sure that the drill pipe was centered in the well hole. If it had been off center, the unevenness might have contributed to flaws in the cement surrounding the pipe. The company said that it did not do the other centralizer tests because the correct pieces of equipment were not available the night before, and that the ones on hand ran the risk of breaking into three separate pieces.
-- Workers on the rig made mistakes in placing a viscous liquid known as spacer fluid in the blowout preventer instead of further up the pipe to the surface. By doing so, company officials said that the fluid may have mixed with sea water and solidified, blocking a kill valve and distorting pressure in a key hose.
-- Two valves known as flappers might not have closed in a device known as the shoe, which was supposed to guard against releases of gas from below. That might have undermined one of many obstacles to a blowout.
-- The contractor handling the drilling mud moved it from tank to tank, making it hard to notice an increase in fluid that might have alerted rig workers to gas in the well. "We cannot see how fluid volumes were being monitored," said Bly.
-- After the accident, BP discovered four leaks in the blowout preventer's hydraulic system, which is supposed to help trigger the closing of valves in an emergency.
Bly said that BP had briefed Interior Secretary Ken Salazar and congressional committees investigating the accident on the status of BP's internal inquiry, just one of many investigations. Bly said "we're at the beginning" and that new information could change what BP's investigators are currently thinking. "There are many things that we feel are far from conclusive," he said. "This is very much a work we're in the middle of."