Tension Leg Platform

The mooring system of a TLP is vertically oriented and consists of tubular steel members called tendons. The group of tendons at each corner of the structure is called a tension leg. The tendon system is highly tensioned due to excess buoyancy of the platform hull. The high tension limits horizontal offsets to a small percentage of water depth. Vertical motions of the TLP are nearly non-existent due to the tendon’s high axial stiffness (low elasticity). Roll and pitch motions are also negligible.

Advantages of the Tension Leg Platform

• Surface wellheads (dry trees)
• Vertical access to wells through TTRs
• Support of remote wells through SCRs
• Drilling and workover capability
• Improved motion characteristics compared to Spars and Semisubmersibles
• Full integration and commissioning prior to installation
• Proven performance record

Limitations of the Tension Leg Platform

• Water depth / payload limited
• Cost of tendon system
• Vertical mooring system does not provide active control of horizontal position (e.g., for well access)

The TLP is very effective once installed. However, the tendon system is critical to performance and must be carefully designed, fabricated, inspected and installed to ensure long term performance and robustness. Tendon installation requires specialized equipment and careful execution.