Free Standing Hybrid Riser Global Parametric Sensitivity Analysis and Optimum Design

With a rigid pipe for the vertical free standing portion and a flexible pipe for the near surface dynamic motion region, Free Standing Hybrid Riser (FSHR) has been widely accepted within the offshore oil and gas industry, especially in the field of West of Africa, Gulf of Mexico and field of Brazil. So the optimum design of FSHR system is becoming increasingly meaningful and necessary. This paper mainly presents the parametric sensitivity analysis and optimization of deepwater Free Standing Hybrid Riser (FSHR). First of all, a general description about FSHR system is given in the introduction. The components of FSHR and their function are presented in detail. Secondly, the procedure for parameters optimum design is discussed, and in order to make it looks more clearly and directly, a flowchart is illustrated to show the process. Considering the design requirements for a deepwater FSHR, the optimum design mathematic model is presented with the optimal objective - minimum of FSHR total weight which is directly proportional to project cost. Thirdly, a design instance is given to make clear the flow of FSHR optimum design with the best performance. The global strength analysis is carried out with the use of generic FEA tools. Then the parametric sensitivity analysis is performed through Single-Variable Control Method. Based on FSHR global strength analysis, four sensitivity parameters are carried out, and the minimum bending radius (MBR) of Flexible Jumper and the max von Misses stress are checked according to API RP 2RD. The relationship between sensitivity parameters and the response of the riser system is briefly discussed and the regress analysis can be used to quantify the relativity. Finally, the parameters optimum design is analyzed and the optimum results are checked to ensure its validity.