Research On Aided Floating Technology During TLP Undocking And Towing

With the development and utilization of deep-sea oil and gas resources, countries around the world are actively building the deepwater offshore drilling platform. As a newly arisen deepwater offshore drilling platform, the design and construction technology of tension leg platform (TLP for short) has attracted many countries'attention. When built in the dock, the TLP is usually unable to undock successfully due to its special structure and insufficient water depth in the dock. At the same time, aided floating technology are utilized to assist the TLP to undock safely. Generally, aided floating technology refers to adding aided floating bodies (rubber airbags or steel buoyancy tanks). Therefore, how to arrange the aided floating bodies becomes the key issue of aided floating technology during the construction of the TLP.In the paper, the arrangement form of rubber airbags or steel buoyancy tanks during TLP undocking is studied. The main research content is as follows.(1) Based on the basic principle of aided floating bodies scheme design and combining the characteristics of aided floating bodies and TLP,5 feasible schemes are presented and their arrangement forms and applicabilities are described.(2) Floating conditions and stabilities of 5 schemes are calculated. Intact stabilities of 5 schemes are checked according to the relative regulation. The effects of 5 schemes on the stability are compared and analyzed.(3) Based on CFD and numerical analysis theory, water resistance in the process of towing is calculated by using Fluent. Wind resistance is calculated by referring to the relative guideline. Then towing resistance is obtained. Taking Z-propeller tug as an example, calculate the power of tugboats, design tugboat outfit scheme and preliminarily estimate the rental charges for each scheme. Later, the effects of 5 schemes on the towing resistance and costs of tugboats are compared and analyzed.(4) Fixation methods and dismantling technologies of aided floating bodies are studied. Based on lifting and jacking, restrain formulae during installation of aided floating bodies are presented and appropriate scheme are given considering TLP's structure. While lifting and jacking, installation flows of rubber airbags and steel buoyancy tanks are described. Then the priority of the 5 schemes is given in terms of construction.(5) In terms of safety, economy and construction,5 schemes are analyzed and compared. Optimum recommended scheme is given in different conditions. In addition, it can provide technical support and scheme reference for the study of aided floating technology during the construction of TLP in the future.