BP's internal probe faults others for oil spill

An internal report by British Petroleum (BP), which has always said that the Gulf of Mexico oil spill caused by the explosion of the Deepwater Horizon oil rig was a complex accident, has thrown up the possible causes for the tragedy - all that point fingers at its contractors.

In an internal investigation conducted by BP and shared with US lawmakers, the London-based oil major has pinned down the accident to failure of seven mechanisms – all pointing to contractors deployed by BP at the site.

According to BP, the seven mechanisms that failed were
1. Cement that seals the reservoir from the well
2. The casing system, which seals the well bore
3. The pressure tests to confirm the well is sealed
4. The execution of procedures to detect and control hydrocarbons in the well, including the use of the BOP
5. The BOP emergency disconnect system, which can be activated by pushing a button at multiple locations on a rig
6. The automatic closure of the BOP after its connection is lost with the rig, and
7. Features in the BOP to allow remotely operated vehicles (ROV) to close the BOP and  thereby seal the well at the seabed after a blow out.

But a memo leaked by two US Congressmen, Henry Waxman and Bart Stupak, showed that BP knew hours before the explosion that pressure tests on a drill pipe showed extreme flaws as equipment that was supposed to provide fail-safe protection against a blow out, also had problems.

The memo, however, did not say as to who made the decision to go ahead with the drilling operations even after the problems were found, although it did say that supervisors from BP and the rig operator were present on the rig when it exploded.

According to a report in The Washington Post on 23 May, BP had agreed in 2004 to the installation of a test valve and replacement of another key part on the Deepwater Horizon's blowout preventer, even though it acknowledged that doing so would reduce redundancies and increase risks on the drilling rig.