| Nowadays,the exploration model of deep-sea oil and gas field based on the subsea production system(SPS)has been widely studied because of its economic superiorities.The installation technologies of the SPS have been monopolized by a few overseas' companies.There are no installation technologies which we own intellectual property,which restricts the development of the SPS in our country.Considering the poor situation of China in this field,it is necessary to design a set of complete installation technologies to fill gaps in the SPS technologies and exploring deep-sea oil.Besides,the lowering structures and umbilicals are the key components for the installation,which suffer from complex forces such as environmental force,gravity.These forces may cause the strength and fatigue failure of these key components.However,there are very little researches on the key mechanics issues for the installation technologies,it is difficult to ensure the security,stability and accuracy of the installation process.Thus the research on the key mechanics issues is helpful for building the safety guarantee technology.Based on the above points,the thesis mainly includes:1.Design of an installation technology for the SPS based on a floating device.The characteristics and limitations of mainstream installation methods for the SPS were systematically summarized and analysed in the paper.Several principles for the design of an installation method were discussed.Based on the principles,an installation technology for the SPS based on a floating device was designed.The structural and functional characteristics of the device,as well as related installation scheme were described in details.2.Dynamic response analysis for the lowering structures under the wave and current loads.Based on the structural dynamics,mechanics of material and wave theory,mechanical analytical models of the lowering structures were established.The formulas for calculating the lateral displacement and axial tension along the structures were deduced.Theoretical solutions were calculated under a specific condition.FE models of the lowering system were established and related numerical simulations were performed to prove the accuracy of the formulas.Along with the comparison of the dynamic response values with other technologies,the advantage of the designed technology was validated.What's more,an installation system model was established using AQWA.And related dynamic response program in time-domain was developed to discuss the effect of the parameters on the lowering system,which provided the basis for the safety guarantee technology.3.Mechanical properties analysis for the cross section of umbilical.Based on the finite element software ANSYS,the umbilical was modelled as a three-dimensional helical structure.Taking the contact and friction into consideration,the nonlinear behavior and mechanical properties of the umbilical were analyzed.Compared with the present theoretical solutions,the accuracy and advantages of the FE model were validated.Parametric analysis was conducted to study the effect of the parameters on the mechanical properties of the umbilical,such as the helix angle of the armor layer,frictional coefficient and diameter of the steel wires.The parametric analysis laid the groundwork for the dynamic response analysis of the umbilical and gave some guidance to the optimization of the mechanical properties for the umbilical.4.Dynamic response analysis for the umbilical under the wave and current loads.Based on the mechanical properties analysis for umbilical,an equivalent simplified model of the umbilical in operation condition was built using AQWA.The global dynamic response analysis of the umbilical in operation condition was performed.The effect of the environment loads and water depth on the response of the umbilical was discussed.The analysis provided guidance for establishing an effective and simple method for the dynamic and fatigue failure analysis of the umbilical,as well as building the safety guarantee technology. |
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