Stability Analysis Of Pipe String And Wellhead Considering Vortex-induced Vibration In Deep Water Riserless Drilling

After years of exploitation,the exploitation of terrestrial oil and gas resources has become more difficult.Therefore,the marine environment with great potential for oil and gas reserves has gradually become a new trend.However,the environment for deepwater oil and gas exploration and development has more complex challenges than land.For example,the riser is disturbed by wave current,the shallow seabed geological disaster,and the narrow density window.Especially in deep water riserless drilling,the stresses of the riserless-wellhead-pipe system are a composite effect under the action of external force.Through research,this paper summarizes the current development status of the riserless drilling technology and the corresponding pipe and column mechanics research,and come up with the main contents and technical ideas of this paper.First,increase the consideration of the drilling platform(ship)'s effect of lifting on the lateral vibrational deviation of the pipes;the second is to consider the influence of vortex-induced vibration on the pipe during the seawater section.Starting from the mechanical analysis,this paper establishes a nonlinear FEM model for riserless drilling,and solves the solution under static state.Based on this result,combined with VIV induced by the wave current force on the pipe,realize the dynamic simulation of the system using the improved Van der pol wake oscillator model.The stability and its influencing factors of the riserless drilling pipe string and wellhead are analyzed.Finally,the existing models are compared with the existing commercial FEM software to verify their availability.