Study On Sealing Structure Of The Top Tensioned Riser Hydraulic Connector And Thermal-structure Coupling Analysis

Top tensioned riser is one of the most commonly used risers in deep-water oil and gas development.The hydraulic connector,at the bottom of the top tensioned riser,allows connection between the top tensioned riser and the subsea wellhead to ensure tight connections without leakage.In this paper,the top tensioned riser hydraulic connector for18.75" H4 wellhead is taken as the research object.The structural design of the hydraulic connector,the mechanical characters of the sealing structure,the steady-state heat transfer and the thermo-structural coupling analysis of the hydraulic connector,test research on sealing performance are carried out.The research status for subsea wellhead connectors and the sealing ring is investigated and analyzed.After analyzing and comparing various types of wellhead connector structures,sealing mechanism and working principle,the metal-nonmetallic composite seal with sealing and sealing pressure test function is selected as a sealing solution,and the locking piece mechanism with hydraulic drive is selected as a quick locking and unlocking solution.And the structural design and material selection of key parts of the hydraulic connector are completed.According to the structure of the metal-nonmetallic composite seal designed,the mechanical models of the metal sealing ring in preloaded and operating states are carried out.The relationship among the minimum axial preload,the internal pressure and the average contact stress are derived.The finite element analysis of sealing contact characteristics of the hydraulic connector sealing structure is completed to determine the minimum axial preloads of the metal sealing ring in preloaded and operating states.In order to obtain the bearing capacity of the hydraulic connector seal structure,the mechanical models of the metal sealing under the tensile load and the bending moment load are carried out.To solving the hydraulic connector heat transfer problem,the equivalent thermal conductivity and composite heat transfer coefficient are introduced to establish the model of the hydraulic connector heat transfer.Steady-state temperature fields of the hydraulic connector in high temperature and low temperature conditions are analyzed.Steady state temperature fields obtained are set as static loads applied to the hydraulic connector staticanalysis model.The hydraulic connector is subjected to the thermo-structural coupling analysis of the steady-state temperature field to explore the sealing performance of the hydraulic connector under the limit temperature.The test device is designed to conduct a hydrostatic test for the metal seal specimen,to test the working and sealing performance of the metal seal.The relationship between the minimum axial preload and the internal pressure is obtained and compared with the theoretical analysis results.The pressure-holding ability,steady-state temperature distribution and thermo-structural coupling stress of the hydraulic connector were tested by the temperature testing device to study the influence of the steady-state temperature field and pressure on the sealing performance of the hydraulic connector.