| With the development of China's economy and the rapidly increasing demand of oil and gas resources, the higher oil import dependence has become one of the important factors that affect national economic security. Due to the fact that oil fields are gradually dried up onshore in China, the future growth potential of oil and gas mainly concentrate in the ocean, especially deep sea oil and gas resources. At present, sea oil and gas exploration and development in our country lacks key link which is subsea production system and its equipment and technical services can only rely on foreign countries. The characteristics of the subsea tree is high cost, large volume and the high concentration of internal structure. In the process of offshore installation operations, installation will be affected by the joint action of sea, wind and flow and the operation risk is very big. If the error appeared in the process of installation in the deep down, the consequences will be unimaginable. Therefore, it is necessary to study the installation of subsea tree.In the paper, based on the investigation of subsea tree installation and related research results at home and abroad about the basis of the system, discussing the different structure and installation feature of subsea tree. Expounding the installation process of subsea tree, mainly including installation method, system installation order, the main installation phase, the basic installation steps and the installation contrast of the horizontal and vertical tree. At last, giving the sample of the drilling riser installation method. Based on the drilling riser installation method, studying the down process force and the relevant theories of environmental load, establishing the mechanical analysis model, and using MATLAB programming to solve the model. OrcaFlex software is used to analyses the drilling riser and tree for different water depths of mechanics analysis, dynamic analysis, parameter sensitivity analysis and the analysis of the parameters of orthogonal test. At last, getting 1500 m tree installation operation window.The study shows that according to different installation tools, the current subsea tree installation methods can be divided into three types:direct decentralized method, drill pipe installation method and drilling riser installation method.In particular, the drilling riser installation method with its own advantages is used more and more widely; Von Mises stress and maximum drilling risers are located in the upper end of the drilling riser while Christmas tree installed at different depths. the closer the end of the value is greater, and there is a stress concentration phenomenon; Maximum lateral displacement of the drilling riser located at the bottom, and with the water depth increases gradually increase, but the rate of increase continues to decreasing; Maximum lateral displacements at the bottom of the drilling riser decreases with fluctuations in the frequency and time of fluctuation; Current velocity has a greater impact on the response to lateral displacement during the installation of the drilling riser and its mechanics, so the installation program design should be a focus of current velocity installation environment; With the increase of the weight of the Christmas tree, the lateral displacement of the drilling riser, bending moments and the Von Mises stress has decreased, which will be conducive to the stability of the subsea tree during the installation of the entire system.These results is helpful to further know the subsea tree force of the drilling riser of installation process, it will provide certain scientific reference for the tree installation design, and the development of ocean oil and gas has a certain reference function. |
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