Page 124 - Drilling Technology in Nontechnical Language

Chapter 5 – RIG SELECTION AND RIG EQUIPMENT 115

then towed to the next location. The rig is highly automated; the company
claims that someone could sit in an office in Dallas and drive it remotely!

Fig. 5–5. Rotating coiled tubing rig near Odessa, Texas
Photo courtesy Reel Revolution Limited.

Semisubmersible

A semisubmersible rig is large, and some are very large. The rig sits on
steel columns (between three and eight of them), under which are buoyancy
chambers (called pontoons). When under transport between locations, the
pontoons are partially empty (with some water as necessary for stability)
so that the rig floats high out of the water.

Once the rig is in position over the well site, ballast water is pumped
into tanks located within the pontoons and columns. The rig thus becomes
lower in the water, and in this position, the rig will move less than it would

in the transport state when influenced by the waves and wind. A big
semisubmersible rig can continue to operate in pretty bad weather.

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