Hydrodynamic Coupled Analysis Of Multiple Floating Platforms

21st century is a marine energy development century, and the development of oil and gas resources is an important component of marine resources development. With the rapid development of the marine resources,multiple floating platforms are becoming more and more popular which were considered to be very challenging in the past. One of the significant challenges for this field development concept is the increased payload and functional requirements for facilitating drilling on the production platform. The increased topside capacity will significantly increase platform capital cost. Therefore, many of today's deep water hydrocarbon reservoirs have been developed with subsea solutions. A solution to the challenge is tender assisted drilling,which reduces the payload and functional requirements on the production platform.Therefore offshore multiple floating platforms which consist of a production tension leg platform and a semi tender assisted platform have significant advantages in the deepwater.In order to meet the demands of offshore operations,the distance between the multiple floating bodies is relatively small.In order to prevent collisions between the floating bodies, and guarantee the normal operation in deepwater,hydrodynamic coupled analysis of offshore multiple floating platforms has an important value of engineering application.In this paper, time domain coupled method is employed to analyze offshore multiple floating platforms which consist of a production tension leg platform and a semi tenser assisted platform in order to obtain the motion responses of two platforms and the dynamic response characteristics of mooring systems. The main research contents of this paper can be summarized as follows:1.Research is carried on the hydrodynamic performance of offshore multiple floating platforms. Based on linear wave theory and second order wave theory,3D Green's function is adopted to solve the diffraction and radiation potential.Moreover, the numerical simulation of the multiple drilling system is carried out by AQWA software,so as to get the hydrodynamic interaction effect on added mass and damping coefficient,the first order wave excitation and the steady drift force.2.Research is carried on the motion responses of a single floating system(a production tension leg platform or a semi tenser assisted platform) and mooring system dynamic response. Time history of responses in six degrees of freedom and the mooring tension areobtained.Spectrum analysis is carried through the Fourier transform on the response results.And the contribution of the each component of the frequency response to the motion response are discussed.3.Under combination of wind, wave and current,time domain coupled analysis of the hydrodynamic performance of offshore multiple floating platforms are studied.The interaction effects(hydrodynamic interactions and transverse mooring) on the tension leg platform and semi-submersible platform motion responses and mooring system dynamic response are discussed.At the same time, features of offshore multiple floating platforms under different wave directions are simulated.