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The mud losses of approximately 15,500 bbls during drilling at Macondo
indicated that BP should have taken additional precautions during the
production casing cementing operation. With the known losses experienced in
the well, BP’s failure to take additional precautions, such as establishing
additional barriers during cementing, was a contributing cause of the blowout.

As discussed above, API RP 65 contains recommended practices
regarding cementing operations that, at the time of the Macondo blowout, were
used by many operators drilling wells in deepwater in the Gulf of Mexico. Some
of the steps that BP took during the cementing of the Macondo production casing
were not consistent with API RP 65 recommended practices, including the
following:

 BP did not circulate a minimum volume of one bottoms‐up (the volume
needed to be pumped to push the mud at the bottom of the wellbore to
the surface) once the casing was on bottom, and the mud conditioning
volume was less than one annular volume;

 With the casing shoe not run to the bottom, BP did not fill the “rat hole”
with a higher weight mud capable of preventing cement from falling into
the rat hole and thereby displacing rat hole fluid into the cement column
and compromising the cement’s properties; and

 The hole diameter was less than three inches greater than the casing
outside diameter.

With respect to the production casing cement job, BP and Halliburton did
not employ the industry‐accepted recommended practices described above. BP
and Halliburton’s failure to perform the production casing cement job in
accordance with industry‐accepted recommendations as defined in API RP 65
was a contributing cause of the blowout.

BP chose to land the float collar across a hydrocarbon‐bearing zone of
interest in the Macondo well, instead of at the bottom of the shoe. If the float
collar had been at the bottom of the shoe, the cement job would likely have been
more overbalanced (i.e., greater pressure from the cement relative to the
pressures from the well). This increased overbalance would likely have allowed
the rig crew more time to recognize that hydrocarbons were flowing in the well
and more opportunities to take measures to control the well. BP’s decision to set

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