Which casing string is used to support the BOP stack?

• A. Float Collar
• B. Surface Casing
• C. Centralizer
• D. Guide Shoe

Answer: (B)

The BOP stack is supported by the surface casing. After the well is drilled, the surface casing is cemented in place and serves as the structural foundation for the wellhead and BOP assembly. The casing head or wellhead is attached to the top of this string, and the BOP stack mounts onto that connection, so it needs a solid, stable casing string to bear the loads and provide a secure seal.

Other options don’t serve this foundation role: a float collar is used in cementing to prevent backflow, centralizers keep the casing centered in the borehole, and a guide shoe helps steer casing drill-paths. None of these provide the structural platform for the BOP like the surface casing does.