Page 77 - test2

 Limiting the volume of cement to approximately 51 bbls meant that any
contamination of the cement by mud could reduce the effective coverage
of annular and/or shoe track cement.

These decisions by BP and Halliburton with respect to planning and
conducting the Macondo production casing cement job were possible
contributing causes of the blowout.

BP’s well site leaders and the Deepwater Horizon rig crew failed to
recognize the accumulating risk associated with several possible anomalies that
could have contributed to the shoe track cement’s failure to prevent hydrocarbon
ingress into the well. These problems include:

 The higher pressure needed to convert the float collar from “fill” to
“check” (3,142 psi instead of a maximum of 700 psi) could have damaged
components of the float collar (including the auto‐fill tube and shear pins);
 The float collar may not have converted because the crew used an
insufficient flow rate and pressure. The float collar was designed to
convert at a range between 5 bpm and 7 bpm, while the actual flow rate
never exceeded 4.3 bpm;
 The bottom cement wiper plug that landed on the float collar required 900
psi to 1,100 psi to burst the disk. However, the burst disk did not rupture
until 2,900 psi was applied, which indicated that there may have been a
blockage in the float collar;
 The check valves on the float collar may not have properly sealed as a
result of damage to the flapper valve pins, or related components, or may
have only partially sealed as a result of debris across the seal areas;
 Lost circulation material or other debris in the mud system could have led
to the need to use increased pressure to convert the float collar. If debris
was present, there would be no assurance that conversion could be
achieved even with the use of higher pressures;
 The shoe track cement may have been contaminated by mud in the rat
hole swapping out with the cement, due to a density differences between
the cement and the mud; and
 Except for a couple of surges or spikes, the flow rate used by the crew was
too low to convert the float collar.

The failure of BP’s well site leaders and the Transocean Deepwater Horizon rig
crew to recognize the risks associated with these multiple problems that

72