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support on which the BOP stack (and, subsequently, the completion tree) will be

landed, connected, and sealed. The function of the casing hangers is to hang off

and support the load of the casing strings within the subsea wellhead housing.

With this housing, a guide base system, consisting of a temporary guide base

(TGB) and a permanent guide structure (PGS), will provide an anchor for the

guidelines and serve as the initial support structure for installing the wellhead

system.

The first piece of subsea equipment used in a typical floating drilling

operation is the TGB, through which the drilling assembly will be guided to drill

the 36-in. diameter conductor hole.

Figure 6.15 - Temporary guide base. (Courtesy Vetco)

The temporary guide base has four guideline attachments on a 6-ft radius

(fig. 6.16). Its four anchor spikes will penetrate 18 in. of the sea floor. The center

of this TGB is a funnel-shaped landing ring that accepts the gimballed base of the

permanent guide structure, even in soft-bottom conditions. The permanent guide

structure, adaptable for drilling or jetting, supplies the landing seat for the 30-in.

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