MULTI-OBJECTIVE DESIGN OPTIMIZATION OF DRILLING RISER OPERABILITY ENVELOPE FOR ULTRA-DEEP WATER

This paper presents an efficient methodology for multi objective design optimization of drilling riser in ultra-deep water considering maximum operability window and minimum weight of drilling riser system. As exploration activity moves to ultra deep waters, the associated drilling cost increases, putting pressure on the operators to expand the drilling operability and reduce costs. Drilling systems are an integral part of oil and gas exploration particularly in deep waters. The drilling riser design requires a time-consuming design loops and scenarios analyzed with different FEM models, such as connected mode, drift-off, hang-off, recoil analysis, emergency disconnection, etc. The main purposes of this work is to improve the safety and cost-effective for drilling riser design by employing multi-objective optimization based on metamodel. The Radial Basis Function (RBF) metamodel is constructed by the design of experiment sampling and is utilized to solve the problem of time-consuming analyses. In the optimization module, multi-objective optimization by a non-dominated sorting genetic algorithm II is performed. Thereby, RBF optimum solutions forming a Pareto set are obtained and compared with accuracy analysis to determine their validity. The optimization results indicate that the proposed optimization strategy is valid and provide an efficient optimization design method for drilling riser in ultra deep water.