| 摘要 |
Subsea drilling and foundation templates are lowered from a semi-submersible drill rig and levelled utilizing the drill string hoisting apparatus including a heave compensator suspended from the travelling block of the hoisting apparatus, a riser string suspensed from the heave compensator and connected to the template at substantially its center of gravity and further including a constant tension rotary drum air powered hoist supported on the riser string below the heave compensator and having a tension cable secured to a fixed reference point on the seabed such as one of the template supporting piles. The tension on the cable may be selectively adjusted to dampen the motion of the riser string during levelling procedure so that the position of the template with respect to its supporting piles may be referenced and the template secured to the piles when a level condition is reached.
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