This paper is primarily concerned with a novel floating platform DDMS i.e. Deep Draft Multi-Spar, which is especially designed for drilling and production in deep and ultra deepwater field. The hard tank of DDMS is composed of four deep draft spars which have relatively small diameter. A particular spar is added at the center of the platform in order to create a closed moonpool which is open to the sea at the bottom to protect the top tensioned risers. Considering the platform's stability, a soft tank filled with metal or high density fluid is used to make the CG i.e. center of gravity under the CB i.e. center of buoyancy. Meanwhile three heave plates are employed to decrease the heave motion amplitude. The main advantages of the DDMS platform are less fabricative cost and difficulty, better motion behavior, more design flexibility etc. Firstly the concept of DDMS is introduced and the process of conceptual design is described. Then the 1st order hydrodynamic information is obtained by 3D high order BEM based on the diffraction and radiation theories. The numerical model is established and RAOS are acquired later. Newman's approximation is adopted to predict the 2nd order hydrodynamic information and finally the motions of time histories of 3 hours are simulated. The response spectra under three different extreme ocean environment conditions are analyzed and compared. The simulative results reveal the favorable motion performance especially the heave response.
The requirement of oil and gas increases fleetly with the rapid development of industrial and civil utilization. Recently the offshore petrol industry strengthens expansion towards the deep and ultra-deep water field as well as more and more deepwater drilling and production units are demanded. It is well known that, the bottom fixed platform is not suitable for deepwater and should be replaced by floating units. The conventional types of floating platforms mainly include semisubmersible, TLP and Spar platform.
