They highlight the clear difference between drilling-phase equipment and post-drilling wellhead configuration:
During drilling (BOP Stack)
Large bore sizes
High pressure ratings (5K / 10K psi)
Multiple rams (Pipe Ram, Blind/Shear Ram)
Designed mainly for well control and safety
After drilling (Wellhead / Completion phase)
Smaller internal diameters
Casing-oriented components
Focus on well integrity, flow control, and future production
Same well, same location, but different objectives, which explains why dimensions, pressure ratings, and equipment layout change from one phase to another.
Every spool, flange, and valve is selected for a specific risk and purpose.
Rig life is not only about drilling depth — it’s about understanding the equipment behind every decision.