Flexible Riser Configuration Design In Shallow Water And Compliance Research

Flexible pipe as a marine product was introduced to the offshore market in the early seventies. It is widely used for a range of water depths and can accommodate large floater motions. While much focus is given to the challenges of designing and manufacturing riser system for extreme deep water, the challenges are certainly not less when one tries to push the limit at the other end of the spectrum:in very shallow water. Due to the advantage of FPSO, flexible risers are being used in extremely shallow water. The design will become even more challengeable if it combines with harsh environment and significant vessel motions. The work of this dissertation is a part of "Key Technology of offshore flexible pipe" project supported by High Technology Research and Development Program of China (863).The traditional design process of flexible riser configuration usually contains 3 steps: conceptual design, preliminary design and detailed design. It will take a lot of time to complete the design, for iterative analysis in this process need unpredictable design cycle, when the riser applied in shallow water. So, in order to design the riser configuration efficiently, serial steps are taken as fallow.First, the design and analysis methods of flexible riser studied at home and abroad are summarized. Based on this experiences, problems of flexible riser applied in shallow water are studied in further depth. Aim at solving this problems, a new method is improved in preliminary design process.Second, considering failure model of flexible riser both in near and far position in shallow water, the parameter analysis is implemented to study the relationship of riser configurations and failure modes, and obtaining the performance curves of this relationship to actualize the rapid design of riser configuration in shallow water.Finally, utilizing the improved method in this dissertation to design a flexible riser configuration, which is used in a single point mooring system in about 50 meters water depth. After 3 steps of design process, a new configuration is gained and prove to be applicative.The work of dissertation will play a significant importance on the design of flexible riser, umbilical, cable and flexible offshore structures in shallow water.