Page 271 - Drilling Technology in Nontechnical Language

262 Drilling Technology in Nontechnical Language Second Edition

Normally, a BOP stack would have at least one bag preventer and
two ram preventers, as shown in figure 11–5. BOP stacks for deeper wells

might have up to four ram preventers and two annular preventers. The ram
preventers generally have a higher pressure rating and are always installed
below the bag preventers. If only two ram preventers are used, the bottom
set will normally be blind-shear rams, and the upper set will be pipe rams.
One reason for placing the blind rams on the bottom is that if the pipe

rams or annular leaks, it is possible to close the blind rams below and fix
the leak above.

Fig. 11–5. Land rig blowout preventer

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