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2. Float Collar Conversion Attempts

On April 18, at approximately 3:30 a.m., the Deepwater Horizon crew
started running the 9‐7/8 x 7 inch long string production casing and finished the
procedure at 1:30 p.m. on April 19. After the casing string landed, the crew
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attempted to convert the float collars in preparation for pumping production
casing cement into the well. Based on information that Weatherford supplied,
the float collar conversion should have occurred with a differential pressure of
between 400 and 700 pounds per square inch (psi), which required a calculated
pump rate of five to seven barrels per minute (bpm). A successful conversion of
the float collar would result in the float collar’s two check valves moving into a
closed position, which should prevent flow of cement (or other fluids) up the
casing.

The crew made nine attempts to establish circulation through the float
collar in an effort to convert the float collar, increasing pressure on each attempt.
The crew finally established circulation on the ninth try, at pressure of 3,142 psi.
After circulation was established, the circulation pressure was only 340 psi,
which was lower than the pressure of 570 psi predicted by Halliburton’s
computer model. The pump rate required to move mud into the well and
through the shoe track (circulating pressure) never exceeded approximately 4
bpm, which was less than the five to seven bpm that Weatherford determined
was necessary for float collar conversion.

Because Bob Kaluza, the BP well site leader, was concerned about the low
circulating pressure, he directed the rig crew to switch circulating pumps to
determine whether doing so would improve circulating pressure. They
eventually concluded that the pressure gauge they had been relying on was
inaccurate.
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Nathaniel Chaisson, an onsite Halliburton engineer, testified that, after
circulation was established, Kaluza said “I’m afraid that we’ve blown something
higher up in the casing joint.” Chaisson understood Kaluza to mean that he
believed they had not been circulating mud from the bottom of the well up, but

117 BP Daily Drilling reports 4/19, 4/10 (BP‐HZN‐MBI‐000136936; BP‐HZN‐MBI‐000136946).
118 Cocales testimony at 71‐75.

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