Research Of Monitoring Technology For FPSO Soft Yoke Single Mooring System

With the increasing requirement of offshore oil-field development, As the essential core cell in the offshore oil-field development, FPSO is more and more widely used in the shallow sea and deep sea oil development. In a variety of FPSO mooring positioning, overwater Soft Yoke Single Mooring System is widely used in the Bohai Sea of China. As the complicated ocean environment and defect design of mooring structure, several accidents occurred in recent years, severely restricted the oil of normal operation as a whole. The real-time, full-scale and long-term monitoring for the soft yoke mooring system is the most effective way of safety assessment for mooring structure.In the view of the characteristic of soft yoke structure, a monitoring scheme for these FPSO mooring mode is proposed, and the integrated monitoring system for the motion of FPSO and its mooring is designed. The marine environmental load, motion of FPSO and information of mooring stress could be acquired from the sensors installed on the FPSO, mooring leg and yoke, a large number of first-hand prototype measurement data would be obtained. From the scene of the sensors selection, equipment installation, data processing in software system, etc, FPSO soft yoke mooring monitoring system is demonstrated in this paper.Based on a long-term of field monitoring for FPSO soft yoke mooring system, the obtained measured data are compared and analyzed. This study analyzed the relations of FPSO motion and mooring posture, found that in some cases, mooring leg exist long cycle, large lateral oscillation phenomenon and deviate from its equilibrium position, which produce great torque which have a devastating effect on the soft yoke. By comparison and analysis of a large number of measured data, revealing the yawing motion of the FPSO is the main reason for this phenomenon.