New DNV investigation report cites trapped drill pipe as cause of Macondo blowout


New DNV report cites trapped drill pipe as cause of Macondo blowout

The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE)/U.S. Coast Guard (USCG) Joint Investigation Team have made the forensic examination report prepared by U.S. Det Norske Veritas (DNV) Columbus, the contractor that performed the examination, available to the parties-in-interest in the investigation, members of the Technical Working Group who witnessed the examination at NASA's Michoud Facility in New Orleans, La., and the public.

The examination report cites several different recommendations resulting from the comprehensive investigation. The report states that, “The primary cause of failure was identified as the Blind Sheer Rams (BSRs) failing to close completely and seal the well due to a portion of drill pipe becoming trapped between the ram blocks. The position of the drill pipe between the Upper Annular and the upper Variable Bore Rams (VBRs) led to buckling and bowing of the drill pipe within the wellbore. Once buckling occurred the BSRs would not have been able to completely close and seal the well. The buckling most likely occurred on loss of well control.”

Other recommendations include that the industry examine:
• “the potential conditions that could arise in the event of the loss of well control and the effects those conditions would have on the state of any tubulars that might be present in the wellbore.”
• “the ability of the shear rams to complete their intended function of completely cutting tubulars regardless of their position within the wellbore, and sealing the well.
• “the potential effects or results that undertaking certain well control activities (e.g. closing of the annulars, or closing of the VBRs) could have on the BOP Stack.”
• “the practices, procedures and/or requirements for periodic testing and verification of the back-up control systems of a Blowout Preventer to assure they will function throughout the entire period of time the unit is required on a well.”
• “the practices, procedures and/or requirements for evaluating the vulnerability of the back-up control systems of a Blowout Preventer to assure they are not subject to an event or sequence of events that lead to common mode failure.”
• “the conditions and equipment necessary for Remotely Operated Vehicles to perform various functions (e.g. the BSRs) at a performance level equivalent to the primary control systems.”

The full report is available online at

BOEMRE and the Coast Guard Joint Investigation Team, which is examining the Deepwater Horizon explosion and resulting oil spill, today announced that it will hold a seventh session of public hearings the week of April 4, 2011. The hearings, which will focus specifically on the forensic examination of the Deepwater Horizon blowout preventer (BOP), are scheduled to take place at the Holiday Inn Metairie, New Orleans Airport, 2261 North Causeway Blvd., Metairie, La.

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