ABSTRACT
Compliant tower platform is a fixed rig structure normally used for the offshore production of oil or gas. The platform consists of narrow, flexible (compliant) towers and a piled foundation supporting a conventional deck for drilling and production operations. Compliant towers are typically used in water depths ranging from 1,000 to 2,000 feet, which exceeds the economic limit of the fixed platform. In this paper, Compliant tower platform working principle was fully discussed, in contrast to a conventional skirted fixed platform, a compliant tower does not have battered legs. The overall configuration is usually slender, tubular steel, and the spatial frame is relatively constant with the cross-section size in the direction of the whole structure height. Compared with the traditional fixed platform, the structure is designed to resist the environmental force and inertia force. In addition, the platform structure is the least sensitive to deck weight load among all platforms in deep waters, and the design stress level, steel tonnage and manufacturing cost are significantly lower than deep-water jacket platforms in water depth of more than 1,000 feet. Since the application of the first deep water compliant tower platform in the Gulf of Mexico in 1983, after more than 20 years of development, there are five compliant tower platforms in the world, three in the Gulf of Mexico and two in Angola, West Africa. Compliant tower platform is not a simple evolution and substitution, but a revolutionary technological development. Through the comparative analysis of the existing deep-water compliant tower platforms, the specific technical characteristics and application difficulties of the compliant tower are obtained.
Compliant Piled Tower(CPT)platform has a more slender profile that requires less steel to construct. Due to its small base dimension, regular section geometry much more even distributed weight on skid beam, fabrication of CPT is relative easier. Unlike conventional platforms that are designed to resist forces, the compliant tower is designed to flex with the forces of waves, wind and current. The flex- legs are attached to the lower section of the tower with brace members and shear plates and connected to foundation pile with grout connections. The tower is secured to the seafloor with foundation piles. With flex-legs, resonance is reduced and wave forces are de-amplified. Compared with floating systems, such as tension-leg platforms and SPARs, the production risers are conventional and are subjected to less structural demands and flexing. However, because of cost, it becomes uneconomical to build compliant towers in depths greater than 1,000 meters.
