BOP Tethering

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REDUCE CYCLIC BENDING MOMENTS AND PROTECT YOUR WELLHEAD FROM EXCESSIVE LOADING

With SubseaDesign’s innovative BOP tethering system the cyclic bending moments that occur in the subsea wellhead during offshore drilling operations - potentially causing severe fatigue failure of critical components in the subsea well system - are efficiently reduced without compromising the operational flexibility.

The heart of SubseaDesign’s BOP tethering system is the Linear Rope Tensioner (LRT) which has the capability to continuously pull excess length of rope before application of final tension. Thus, flexibility in adjusting length of rope required for each tension line is provided which overcomes the need to have several lengths of adjustment lengths and hence reduce the subsea rigging time.

The LRT can be equipped with two different configurations for initial tensioning, either by lift line from surface (snatch block) or by a hydraulic operated tensioning unit mounted on the LRT. The latter is fully ROV operated and ideal for use in shallow water or on locations where it cannot be reached from the rig.

The LRT is equipped with a tension monitoring gauge. The ROV can monitor and adjust tension as required. The LRT enables easy interfacing on all types of anchor points, both on templates and seabed, and has a rotational range of 360 degree. Since the rope goes out of the LRT in upward direction, it will not be any clash with surrounding structures.

A complete BOP tethering system consists of several LRT’s which are individually tethered to the BOP. The number of tethers and anchoring coordinates are decided based on analyses of the system to achieve the optimal BOP tethering efficiency. Other optimization factors are loads on the existing infrastructure, well properties and soil conditions. The system is adaptable to different BOP designs.

The LRT can be equipped with two different configurations for initial tensioning, either by lift line from surface (snatch block) or by a hydraulic operated tensioning unit mounted on the LRT. The latter is fully ROV operated and ideal for use in shallow water or on locations where it cannot be reached from the rig.

The integrated load monitoring system ensures that the ROV can monitor and adjust tension force as required. The LRT enables easy interfacing on all types of anchor points, both on templates and seabed, and has a rotational range of 360 degree. Since the rope goes out of the LRT in upward direction, it will not be any clash with surrounding structures.

The WLR system consists of several LRT’s which are individually tethered to the BOP. The amount and anchoring coordinates of the LRT’s are decided based on analyses of the system to achieve the optimal WLR efficiency. Other optimization factors are loads on the existing infrastructure, well properties and soil conditions. The system is adaptable to different BOP designs.

LRT with snatch block
LRT with ITU

SubseaDesign deliveries during a BOP tethering project are as follows:

Specifications:

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