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Scenario 3: Production Casing Shoe Track
Under this scenario, hydrocarbons would have flowed from the reservoir
through the casing shoe, into the well and up the riser to the rig. For this flow
path to have occurred, the shoe track cement would have failed. A number of
factors could have caused the shoe track cement to fail. First, mud in the
wellbore could have contaminated the shoe track cement and caused the cement
not to set properly. Second, the shoe track cement might have swapped out with
the lighter drilling fluid in the rat hole. Third, some of the shoe track cement
could have been lost into the formation. Finally, the failure of the shoe track
could have resulted from a combination of these factors. This scenario is
represented in Figure 8 below.
Figure 8 – Flow up the Production Casing Shoe Track
The approximately 189 foot bottom section of the casing in the well, called
the shoe track, consisted of sections of casing with a reamer‐guide shoe at the
bottom and a dual flapper float collar on top. These sections of casing that make
up the shoe track are meant to contain the top, or tail cement, which in the
Macondo well was unfoamed cement.
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