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horizontally and ensures correct alignment of the guide posts and
conductor housing during installation. The 10-ft guide posts on 6-
ft radius may be fitted with a special post top for remote guideline
connection.
Guidelines are trapped at the top and bottom of each post.
Tension to maintain parallel guidelines is less critical in shallow-
water installations. But for installation in, say, 1,000 ft of water, it
is recommended that each guideline be adjusted and hydraulically
maintained at 2,000 lb plus the weight of the lines for running tool
operations and BOP or (tree) installation. This design provides for
replacement of broken or damaged guidelines by diver or remote
operation.
In actual operation, the TGB is set on the spider beams of
the drilling vessel for attaching the guidelines (usually %- or %-in.
diameter wire rope). Weight material (barite or cement) is added to
the TGB to increase its weight to between 25,000 and 30,000 lb. A
running tool is installed in the four J-slot preparations in the TGB
with left-hand rotation. The temporary guide base is then run to the
ocean floor on drill pipe. The running tool is released by slacking
off the weight of the drill pipe and turning the tool to the right Vs
of a turn. (In the past, each guideline was tensioned with a fixed
weight over a sheave. Today, hydraulic or pneumatic guideline
tensioners, each with 16,000-lb capacity, keep the guidelines in
tension.)
The next operation is to drill the 36-in. hole for the 30-in.
conductor casing. The 36-in. drilling assembly is made up and
lowered through the rotary table and down through the moonpool
or spider deck area.
The next piece of equipment to be prepared is the four-post
permanent guide structure. The PGS is set on the spider beams and
the four guidelines are inserted and trapped in the guide post slots.
The 30-in. casing is then run through the center hole of the PGS.
The first joint of 30-in. conductor (called the shoe joint) has
a nonreturn or float valve included in the guide shoe that is usually
welded to the bottom of the shoe joint. Soft line rope is used often
to guide the 30-in. casing shoe into the predrilled hole. The
individual 30-in. conductor joints are usually 40 to 50 ft long. The
joints of conductor pipe are connected by threadless mechanical
connectors.
Each 30-in. casing joint may have pad eyes attached to
support the conductor joint in the rotary table during running and

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