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Unformatted text preview: ed upon its review of forensic evidence that established the absence of free gas in the annulus, that contamination or nitrogen breakout did not affect zonal isolation in the annulus. B.
Contributing Causes of the Cement Barrier Failure Macondo was an exploratory well with limited offset data, and the differences between calculated and actual pore pressures caused BP to make revisions to the drilling program and casing setting depths, including the depth at which BP set the production casing. BP’s internal guidelines stated that drilling would not be stopped in a hydrocarbon interval, unless doing so was necessary because of operational/pressure/safety issues. BP’s decision to set the casing was based on well integrity concerns and a potential safety issue associated with a zero drilling margin based on 14.1 ppg pressured formation sand combined with a 12.6 ppg formation pressured zone in the same open‐hole section taking losses. Additionally, the production casing string shoe was set in a lamina...
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