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Anadarko, that it chose to terminate the well at 18,360 feet MD, based on
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concerns about well integrity and safety related to this loss of drilling margin.

By terminating the well where it did, BP set the total depth of the well in a
laminated sand‐shale interface. BP internal guidelines for total well depth
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specify that drilling should not be stopped in a hydrocarbon interval, unless
necessary due to operational, pressure and safety issues. Typically, total depth
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is not called in a sand section because placing the casing shoe – the section of the
casing between the bottom of the wellbore and the float valve – in a laminated
sand‐shale zone increases the likelihood of cement channeling or contamination
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due to washout, and creates difficulties in logging well data. Figure 3 depicts
the placement of the Macondo well shoe track.

77 Id. BP’s September 2009 Pre‐Drilling Data Package also indicated that, if after drilling the
primary M56 objective there was an onset of pressure requiring a new casing string, no further
drilling would be feasible. See BP‐HZN‐MBI00013494.
78 Sand is more permeable than shale. Therefore, when casing is set in sand, lost returns are
more likely.
79 BP‐HZN‐MBI00013494.
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Cement channeling occurs when the cement slurry in the annulus does not rise uniformly,
leaving spaces and therefore preventing a strong bond.

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