DNV report: Trapped drill pipe caused Macondo BOP failure

摘要

A report prepared by US Det Norske Veritas (DNV) Columbus, the contractor that performed the examination of the blowout preventer on the Macondo well, has been made available to the public. According to the report, "The primary cause of failure was identified as the blind shear 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." The BSRs were unable to move the entire drill pipe cross-section into the shearing surfaces of the blades, and during the shearing process, the pipe was deformed outside the shearing blade surfaces.