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Unformatted text preview: at ballooning is occurring in the well. Mud logging data for the Macondo well demonstrated that the production casing zone started ballooning between 17,530 feet and 17,761 feet. The daily IADC reports also show that the well flowed back during flow checks following mud loss at those depths. G.
Planned and Actual Total Depth In designing a well, engineers calculate a planned total depth of the well. BP’s February 2009 Exploration Plan estimated the well depth at approximately 20,200 feet true vertical depth. Due to a narrowed drilling margin, BP ultimately decided to stop drilling the well at 18,360 feet. BP set a casing string at 17,168 feet measured depth (sometimes referred to as “MD”) and then continued to drill the final production section of the well. In the section below the last two casing strings, the well lost returns, indicating possible fracturing or formation pressure regression. In response, the crew stopped drilling, pumped in lost circulation materials to seal the fracture, and restored mud circulation. 75 In this open‐hole interval (where no casing...
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