Attitude Control Of Marine Seismic Streamer Under Transverse Flow

Given rich marine oil and gas resources in the vast"Blue Land"of China, it has great significance to carry out exploration on offshore oil and gas resources. Marine seismic streamer system is one of the key equipments in marine seismic exploration, which is highly technology-intensive and involves a wide range of academic areas, and the currently available equipments are totally dependent on imports. In design and application of marine seismic streamer system, it becomes an important objective to accurately predict the attitude of the streamer. More attention has been paid, and more and more scholars and researcher are dedicated in research of this area.Based on the results of previous studies, the present thesis carries out detailed and in-depth research on marine seismic streamer. A relatively perfect attitude simulation system is developed, through which to study the streamer attitudes under different parameters and operating conditions; and on this basis, preliminary studies are conducted on the control of streamer attitude. From the point of providing theoretical basis for marine seismic streamer design and application, this thesis aims at establishing the mathematical model of marine seismic streamer and conducting accurate forecast and effective control of streamer attitude. The main contents and conclusions of the study could be summarized as follows.Firstly, after accessing to a large number of literature data, this thesis reviews the marine seismic streamer system research and development status, and establishes marine seismic streamer as the research object, numerical simulation as the method to conduct attitude simulation and control research on marine seismic streamer. Based on the consideration of factors such as transverse current, negative buoyant, tail drag, stress-strain and so on, a three-dimensional lump mass model is established, thus listing the governing equations about the node and deriving the mathematical formulations after considering the boundary conditions; studying the solution of nonlinear equations, and the Newton iterative method is adopted to solve the governing equations of the node and the simulation program is written in Matlab, through which we get the level and depth offset, as well as the internal tension and water drag distribution along the streamer; detailed analysis of ocean currents, tug speed, tail dragging, Young's modulus and Poisson's ratio, length of elastic section, water resistance coefficient and other factors on the attitude of the streamer is carried out, and regularity conclusions are drawn, which could work as theoretical basis for parameter selection in streamer design. Finally, on the above simulations, principles of attitude control is studied, with the introduction of streamer attitude control device- embedded"bird", a marine seismic streamer control system is developed; analysis of size and number of control forces on the streamer attitude is carried out, and the simulation results shows that embedded"bird"is effective in marine seismic streamer attitude control.This thesis establishes the mathematical model of marine seismic streamer, conducts marine seismic streamer attitude simulation and regularity conclusions are drawn. Moreover, an effective streamer attitude control method is proposed, which all could work as the theoretical basis for marine seismic streamer design and application.