Structure Optimization Of The Sea-star Pontoon Shell Based On NSGA-Ⅱ

With the development of oil and gas exploration in the deep water and ultra-deep water, a series of new marine equipments and production modes have been proposed.China has started lately to make an effort in the development of deepwater marine equipment, but there are still a series of problems to be solved. In this thesis, a new ultra-deep water disastrous marine environment adaptive oil and gas development and supporting system-subsurface tension leg production system(STLP), fitting for peculiar problems of ultra-deep water oil and gas exploration in the South China Sea environment, has been brought into a series of structure design and optimization.STLP system mainly consists of four parts as a well completion and oil and gas transmission system:truss sea-star pontoon, top tensioned riser tensioned by truss sea-star pontoon and connected with subsea wellhead, well completion installed on top of truss sea-star pontoon, flexible jumper connected with well completion and floating production storage and offloading. In this thesis, structure design and optimization of part of truss sea-star pontoon will be done based on structure preliminary design of it.The main research contents include:structure design of shell thickness and stiffening rings of T-SSP truss cantilever structure; structure optimization of the sea-star pontoon shell by means of Non-Dominated Sorting Genetic Algorithm II (NSGA-II) based on API specification; finite element analysis of truss sea-star pontoon.The contribution of this thesis is to operate structure design and optimization of the sea-star pontoon, which lays the groundwork for the future research. Lessons in the application of structure design and optimization of pressure vessel can also be learned from the work in this thesis.