Coupling Mechanics Analysis Of Riser And Wellhead In Deep Water Drilling

Because the stress of the riser string in deep water is very complex,the riser string is easily damaged under the action of waves and ocean current force,resulting in drilling fluid leakage and other problems that pose a great threat to the ecological environment.The stability of the riser and wellhead system plays a decisive role in the safe.Therefore,the coupling mechanics analysis between riser and wellhead system is studied in this paper.Taking the riser and the wellhead system of deep-water drilling as the research object,the static model and the dynamic model of deep-water drilling riser coupling with the wellhead were established respectively,considering the influence of wind and wave loads and the structure of the riser.Based on the static model,the safety operation window of riser and wellhead system in deepwater drilling is determined to provide theoretical guidance for drilling engineering.Main research contents of this paper:(1)consult relevant literature on mechanical analysis of deep water drilling riser and wellhead system to determine the research scheme.(2)according to the deformation characteristics of the riser,the static model of the coupling between the riser and the wellhead was established by the energy method and solved by the gaussian elimination method.The influence of various factors on the deformation of riser and wellhead system is also analyzed.(3)considering wind and wave load,drilling fluid density and tension and other factors,based on the static model of deep water drilling riser and wellhead system,the safety operation window of the riser was established taking the deviation value of the drilling platform and sea current velocity as parameters.(4)the kinetic model of riser was established by energy method and Lagrange equation,and was solved by direct integration method New Marks.The influence of tension,buoyancy block coverage and platform drift on the vertical and lateral displacement of riser maximum oscillation point was analyzed.The fatigue life of deep water riser under the influence of various factors was calculated by BSI and UK Den theory.(5)based on the above research,the deep water drilling riser and wellhead system mechanics analysis software was developed through the GUI interface of MATLAB software.It is used to analyze the deformation,strength and fatigue life of the riser and the wellhead under the action of wind wave and current load,and to guide the on-site operation of the riser.