Research On Vibration Law Of Riser In Deep Water Drilling

Although my country's oil reserves are huge,most of them are located in the deep South China Sea.Therefore,it is necessary to increase the exploitation of oil in deep-water areas,and that put forward strict requirements on my country's deep-sea drilling equipment at the same time.The riser system is the most important and weakest component of the offshore drilling system,and with the harsh and changeable deep sea environment,the force of the riser is more complicated.The mechanical analysis of the riser under complex sea conditions is the research direction of this article,the thesis conducts research from the following aspects:(1)According to the characteristics of small strain and large deformation of the riser under external load,the static mechanics model of the riser is established,and the high-order differential equations are simplified and solved by the central difference method,and the static equations obtained are solved by programming through MATLAB,and the change laws of the lateral deformation,bending moment,shear force and offset angle of the riser under different conditions are obtained.(2)The lateral natural vibration equation of the riser was solved by the infinitesimal method and the energy method.The distribution law of the natural frequency of the lateral natural vibration of the riser,and the change law of the riser lateral vibration and natural vibration under the influence of different factors was obtained.(3)Through the analysis of the force in the longitudinal direction of the riser,the equation of the longitudinal vibration of the riser is obtained.The equation is simplified and solved by the difference method,and the law of displacement and stress of the longitudinal vibration of the riser under different conditions is obtained.(4)The modal analysis of the lateral vibration of the riser was carried out using ANSYS,and the change law of the natural frequency of the lateral vibration of the riser was found under the influence of different factors;the harmonic response analysis was carried out on the basis of the modal analysis,and the resonance frequency of the riser was found to be easy to resonate for the riser.A transient dynamic analysis was carried out,and the law of the displacement,force,deformation and stress of the riser over time was obtained.