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lower test ram needed to be reported to MMS because the leak “did not affect the
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function of the stack.”

The leaks identified did not impede the closing ability of the annular or
ram preventers. These leaks did require the placement of the BOP controls into
the “block/neutral/vent” position in order to stop or slow the hydraulic leak. The
Panel concluded that these leaks did not impede the functionality of the BOP
stack.

M. ROV Interventions

Numerous attempts were made to shut in the well using ROVs after the
rig was evacuated. On April 21, BP initially attempted to activate the middle
pipe ram; however, personnel experienced problems with insufficient ROV
pump volumes and hot stab tools.

On April 22, BP used an ROV to try to activate the autoshear function,
which would have closed the BSR. The ROV was unable to sufficiently cut the
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poppet valve to activate the autoshear. The next ROV attempt, on April 22, to
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close the BSR by “hot stabbing” was not successful either. This attempt was
hampered by the fact that the BOP stack had been modified to convert a variable
392
bore ram into a test ram at BP’s request. The response team was not aware of
this until early May and thus made multiple efforts to hot stab the test ram under
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the belief that they were hot stabbing a pipe ram.

Again on April 22, BP successfully cut the poppet valve for the autoshear.
This is the scenario that the Panel and DNV Report conclude likely closed the
BSR, but failed to seal the well. From April 25 through May 5, BP tried 17
additional ROV interventions to close various BOP rams and annular preventers.
Even though BP was able to operate many of the BOP components, none of the
attempts was successful in shutting in the well.

389 Guide testimony, July 22, 2010 at 229. However, one of the BP well site leaders on the rig,
Ronald Sepulvado, testified that he believed the leak should have been recorded in the IADC
Report. Sepulvado testimony at 26‐27.
390 DNV Report, Volume 1 at 135.
391 Id. To “hot stab” is to insert a hydraulic pump, by means of an ROV’s robotic arm, into a
hydraulic port on the BOP stack to pump hydraulic fluid into the BOP ram closing system.
392 BP‐HZN‐MBI‐00136647; BP, Deepwater Horizon Accident Investigation Report at 172.
393 Testimony of Harry Thierens, Joint Investigation Hearing, August 25, 2010 at 103‐105.

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