Ultra-deep TLP

A TLP in ever increasing water depths requires longer tendons, and the axial stiffness of the tendon system decreases resulting in an increase of the heave, roll and pitch natural periods. Traditional TLP structures can be installed in water depth up to approximately 5000 ft while maintaining these resonant periods below the wave frequency range. For water depths greater than 5000 ft there will be sufficient wave energy at the resonant frequencies causing significant tendon fatigue and thus making the TLP concept less attractive.

Increasing tendon size to reduce periods adds weight to the structure and cost to the tendons, thus making the TLP less competitive in deep water.  A passive air damping system has been developed that can be placed on the TLP columns to damp out the dynamics caused by the longer periods on the tendons. Work has progressed to incorporate this air damping system in the TLP to enable the economic use of this product in water depths up to 10,000 feet. Tests carried out previously have provided essential information for design of these systems. Work in 2007 developed numerical methods for simulating and designing these TLP systems. In 2008 a preliminary design of a 8,000 foot depth TLP was produced.