Numerical Analysis On The Hydrodynamic Performance Of Floating Drilling Production Storage Offshore Vessel

With the increasing demands for global energy,gas and oil resource has been the focal point for global exploration and development.The breakthrough of deep sea oil exploration technology is the key factor in long-term strategy of deep sea exploration.Traditional deep-water oil exploitation needs drilling unit and producing unit,the production period of which is very long as well as expensive cost and low flexibility.Floating drilling production storage and offloading vessel,short for FDPSO,is a multifunction floating platform,which has the integral function of drilling,production,storage and offloading.Its reduction of up-front cost and early production have aroused a wide concern over the globe.Many institutions are very interested in FDPSO and some companies have put it into use.FDPSO has a moonpool which greatly influences the total hydrodynamic performance and Its analysis is very different from ordinary ships.Therefore,the research on the hydrodynamic performance of FDPSO is of great significance.Hydrodynamic performance of a 210-meter long FDPSO is investigated by numerical simulation approach using the calculation software AQWA.3-D potential flow theory is adopted to carry out the frequency domain analysis of hydrodynamic performance of FDPSO hull.The added mass and radiation damping for six degree of freedom(DOF)motion are calculated to show the effect of moonpool with different size,location and draught.The result shows that the fluid piston motion in moonpool increases the heave motion of the hull and that added mass and radiation damping of FDPSO exhibit a peak value which is closely related to the size and draught,but unrelated to the location of moonpool.The hydrodynamic coefficients of FDPSO both in ballast loading condition and full loading condition are analyzed,including response amplitude operator,first order wave exciting force(Froude-Kriloff + diffraction force),second order wave steady drift force.For Wet surface difference is not large,the ballast loading condition and full loading condition is very similar to each other.Based on the Cummins theory,the hull/mooring time domain analysis is performed under the condition of South China Sea.Single point mooring system of FDPSO is preliminarily designed and the equilibrium position and motion response of FDPSO in ballast loadingcondition has been calculated when wind,wave and current are in different directions.The results indicate that FDPSO has a good motion performance and meets the demands of drilling operation condition and self preservation condition in South China Sea.In order to check the safety of single point mooring system,the maximum tensions of cables under intact and one broken cable conditions have been calculated and analyzed.The safety factor shows that single point mooring system under intact and damaged conditions meets the requirement and related assessment has been given.