STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

850 Drilling and Well Completions
A
Figure 4-188. BOP stack arrangrnent for high cellar rigs.
head and the pipe rams are appropriate for the 3 + in. drill pipe. Therefore, as
the drill string is raised to the surface, the stripper rubber in the rotating head
and the pipe ram are available to limit formation gas from coming to the rig
floor. Usually the pipe rams are not employed, and protection of the rig and
its crew from the formation gas is dependent upon stripper rubber in the
rotating head. When drilling a 6$ in. borehole with air, the drill collars
employed are normally 4Q in.
Beginning with the removal of the drill string, the proper procedure for
placing the liner in the example borehole is:
1. Use the 3 + in. stripper rubber in the rotating head to strip over the 4 + in.
drill collars until the drill bit is above the blind rams (but below the
stripper rubber in the rotating head).