Page 123 - Drilling Technology in Nontechnical Language

114 Drilling Technology in Nontechnical Language Second Edition

Fig. 5–4. Huisman LOC 400 casing drilling rig
Photo courtesy of Northern Dutch Drilling Company.

Coiled tubing drilling rig

Coiled tubing has made amazing advances. Instead of drillpipe, reels
of coiled tubing unreel pipe directly into the hole. One major limitation of
drilling with coiled tubing is that the tubing itself cannot rotate. Drilling is
done using a downhole motor to turn the bit. However, as the pipe does not
rotate, it has to slide. This gives rise to all sorts of problems, such as poor
hole cleaning, inability to slide in highly deviated holes, and stuck pipe.
Coiled tube diameters up to 5" are thought possible.

The rig shown in figure 5–5 is the rotating coiled tubing rig designed
and built by Reel Revolution Limited. It overcomes the limitations of
nonrotating coiled tubing; the complete reel rotates around the center of
the well, with automatic counterbalance weights keeping things smooth.
The large A-shaped mast is used to start the well and set conventional
surface casing, and then the reel can take over. Note the road wheels stuck
onto bits of the structure; it transforms into roadworthy trailers that are

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