Research On The Design Of Underwater Buoyancy Equipment Of Marine Flexible Riser

Marine flexible riser is one of the main equipment in the development of marine oil and gas resources. The riser will present various linetypes in water according to different sea conditions and safety requirements, and these linetypes, all need the buoyancy attachment. There are many kinds of buoyancy attachments, and the distributed buoyancy module is the most common and economical. It is mainly composed of outer protective layer of plastic, inner solid buoyancy material and connection structure. Under the action of marine environment load and the movement of riser, the joint of buoyancy module and riser will produce non-uniform contact, even occur the relative sliding, and this phenomenon will cause the failure of the connection. This is the most common failure mode in practical application, so the design of connection structure is particularly important. Although the distributed buoyancy module s structure is simple, the design and manufacture technologies of this kind of attachment are still monopolized by foreign countries. So break the domestic blank, and complete the buoyancy equipment localization, will be a big step forward of the development of marine oil and gas resources of our country.This paper first research and summarize the main forms and classifications of the buoyancy equipment in the world after studying their present situation. This paper proposed a design method of the overall structure, processing materials and connection property of the distributed buoyancy module that based on the failure modes. Then considering the importance of connection property, theory and numerical method is proposed, and a detailed finite element model is established based on the interference connection. Then analyze the contact stress, equivalent stress and connection property of the riser clamp and riser adopting finite element numerical simulation method, we will get a regularity conclusion, and give the best accessor methods of the amount of interference and the length of contact area. Finally, we will get a perfective distributed buoyancy module after the overall designing which belong to an example of863program, and will ensure maintaining normal working condition in a bad condition.The work of this dissertation is sponsored by863program of China, and it has very important significance for the independent research and development of marine flexible riser attachment of our country.