Page 12 - A Primer of Oilwell Drilling, 7th Edition

igging up an offshore drilling rig is usually not as complicated
Ras rigging up a land rig. Most offshore rigs can be moved over 8
Petroleum Extension-The University of Texas at Austin
water with almost no need to disassemble major parts. Onsite, the
offshore rig is stabilized by placing rig supports on the ocean foor
for bottom-supported rigs or, by anchors, anchor chains, and wire

or polyester rope for foaters. Only the dynamically positioned

foaters require no additional support to stay in position during Rigging Up
drilling.
To move most land rigs, crewmembers must disassemble many
of its components. Disassembly is required so the parts can be
transported to the next location and then reassembled. For safety,
rigging up usually takes place only during daylight hours. Even with
lighting after dark, there is too much heavy equipment to move
safely during rig-up.
On most land rigs during rigging up, the rig parts are put
back together so the rig can drill a hole. it involves unloading and
hooking up the rig engines, the mud tanks and pumps, and other
equipment on the site. One of the last steps, and one of the more
dramatic, is raising the mast from horizontal—the position in which
it was transported—to the vertical drilling position. The first rig
component positioned by the crew is the rig’s substructure, which
is the base, or foundation.

SUBSTRUCTURES
A substructure is the framework located directly over the hole; it
is the foundation of the rig. The bottom of the substructure rests
on level ground. The crew places a work platform on top of the
substructure called the rig foor. The substructure raises the rig
foor to approximately 10 to 40 feet (3 to 12 metres) above the
ground. Elevating the rig foor provides room under the rig for
special high-pressure valves and a blowout preventer (BOP) stack that
the crew connects to the top of the well’s casing. The exact height
of a substructure depends on the space needed for this equipment.
A cellar also provides more space for the equipment.

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