Optimization of Taut Mooring System for Deepwater Floating Platform Based on Real Data

With the global oil and gas resource development accelerating its expansion into deepwater and ultra-deepwater areas, taut mooring systems have gradually become key technical equipment. However, the complex coupling mechanism between the material parameters of polyester cables and their dynamic responses has not been fully revealed, and existing design methods mostly rely on simplified models, lacking systematic verification with real environmental data and dynamic responses. Based on on-site platform data, this study proposes a multi-dimensional integrated collaborative optimization design scheme for deepwater tension leg mooring systems, aiming to provide guidance for mooring design projects in similar sea areas and enhance the safety and economy of deepwater mooring systems. To address the nonlinear optimization challenges of multi-body coupled systems, this study establishes a time-domain multi-body coupled model of the platform-riser-taut mooring system and conducts systematic research in combination with the NSGA-II multi-objective genetic algorithm. First, a multi-body coupled time-domain simulation model is constructed based on the actual geometric dimensions of the platform structure and large-scale measured environmental data, covering wave-frequency and low-frequency dynamic response characteristics. Second, statistically representative working conditions are adopted to verify the accuracy of the model's dynamic response. Third, a global sensitivity analysis is conducted to quantify the influence weights of polyester cable parameters and reveal the main control factors of the mooring cable's dynamic response. Fourth, with API-RP-2SM as the constraint, a multi-objective optimization function of the standard deviation of mooring tension and the extreme value of platform displacement is established to solve the Pareto frontier of parameter combinations. Finally, the optimization effect is verified based on typical working conditions, forming a full-process analysis method for mooring optimization. This study provides a digital solution with practical engineering value for the design of deepwater mooring systems. The research results show that: (1) The environmental loads in the target sea area exhibit significant quarterly periodic characteristics, with extreme working conditions in the first quarter accounting for 1%. (2) The length and diameter of the polyester cable have a significant impact on mooring tension. When the length of the polyester cable increases from 1850m to 2000m, a single variable of 2.5% causes the mooring tension to change by approximately 60%. The innovation of this paper lies in proposing an optimization scheme for the mooring system based on the real data from the platform. This method combines environmental data with multi-objective optimization algorithms, breaking through the limitations of traditional empirical design. At the same time, based on the actual data from the site, representative working conditions are selected to support model verification, revealing the quantitative influence laws of polyester cable material parameters on the non-linearity of mooring tension, so as to provide real guidance for similar engineering design and construction in similar sea areas.