Dynamic analysis and multi-objective optimization of an offshore drilling tube system with pipe-in-pipe structure

•A dynamic model of an offshore drilling tube system with pipe-in-pipe structure is developed. The interactions between the inner and outer pipes are verified to restrict the tube deflection.•According to the main effect analyses of optimization parameters, decreasing the top drift of riser, increasing the top tension of riser, and increasing the hanging load of drillstring are demonstrated as the three most significant ways to promote the system stability.•NCGA, Monte Carlo method and six-sigma method are combined as a new multi-objective optimization strategy, which can secure all the suggested designs are optimal and reliable even under perturbations of the design parameters.•Comparing with the single-objective optimization designs, the global optimization degrees of the multi-objective optimal designs are higher. Hence, the multi-objective optimization strategy is suggested for the designs of offshore drilling tube systems in field practices.