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operation, once the pods had been pulled and rerun, only 2.3 gallons of
hydraulic fluid were pumped to close the upper VBR. This would have been an
insufficient amount of fluid to close the VBR had it been in an open state.
Furthermore, DNV found no cut upper VBR hydraulic hoses during
intervention. The VBR was also found to be in the closed position at Michoud.

DNV found that multiple forces acted upon the drill pipe during the
blowout, resulting in the “elastic buckling” of the drill pipe. Elastic buckling can
occur when a structural element loses stability when force is applied. Once the
force causing the buckling is removed, the object reverts to its original form.

The Panel determined that either of the following scenarios, or some
combination of them, led to the elastic buckling of the drill pipe at the time the
blind shear ram activated, which contributed to the failure of the blind shear ram
to cut the drill pipe and seal the well:

 The forces from the blowout acting on the drill pipe pushed the tool joint
into (or further into) the upper annular element. The drill pipe was then
unable to move upward at the upper annular but was able to move
upward at the upper VBR; and/or

 The draw works (the equipment on the rig that supports the drill pipe that
is lowered into the riser) collapsed shortly after the explosions, thus
allowing approximately 150,000 lbs of unsupported drill pipe to act as a
downward force against the upper VBR.
342

Regardless of the conditions that led to the elastic buckling, DNV
concluded that, based upon the physical evidence of the drill pipe, wellbore, and
the BSR blocks, the drill pipe became trapped between the BSR faces, which
prevented the BSR from fully closing. See Figure 12 below. DNV found that
343
these conditions likely occurred “from the moment the well began flowing and
would have remained until either the end conditions changed (change in Upper
Annular or Upper VBR state) or the deflected drill pipe was physically altered
(sheared).”
344

342 Testimony of Daun Winslow, Joint Investigation Hearing, August 23, 2010, at 452.
343
Addendum to Final Report for United States Department of the Interior – Bureau of Ocean
Energy Management, Regulation and Enforcement – Forensic Examination of the Deepwater
Horizon Blowout Preventer (April 30, 2011) (“Addendum to DNV Report”) at 11.
344 DNV Report, Vol. 1 at 4.

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