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A conductor tensioner unit is installed on an offshore jackup rig to apply upward tension on the conductor. The conductor tensioner is installed into the conductor deck and is usually removable in order to protect the unit during transit.
The drilling conductor is the first and outer tubular which runs from the drilling rig into the seabed. It is usually installed by drilling a hole into the seabed, then running the tubular into the hole and cementing to the seabed. It can also be installed by driving with a pile hammer.
Why are conductors tensioned?
- Allows smaller surface conductors such as 9 5/8” or 13 3/8” to be used in any water depth. This results in a significant well cost savings, particularly for exploration.
- Allows the larger conductor sizes (say 20” and 30”) to be used in greater water depths.
- Prevents large cyclic tensions from being induced in conductors when large wave forces are applied. The conductor tensioner applies a “spring” force to the top of the conductor pipe.
- The tensioner prevents overload of the conductor deck compared to a jacking system without accumulators.
Manufacturers of Conductor Tensioners
- Tensa Equipment
- ICON Engineering
- National Oilwell Varco
- Control Flow, Inc.
- M A Childers, Atwood Oceanics; K H Sadberry, Innovative Drilling Systems.(2003). Jackup Conductor Tension System. SPE/IADC 79825.