Design And Research Of Sealing Assembly And Running Tools For Subsea Wellhead System

The research and development of sealing components and tools for subsea well oral system started late in China,which seriously restricted the development of deepwater oil and gas drilling and production equipment and the development and utilization of deepwater oil and gas resources.A two-stage annular metal seal assembly and a hybrid running tool are designed for the subsea wellhead system.The locking sleeve and the driving sleeve of the seal assembly are integrated,and the two-stage metal rigid seal is adopted to improve the reliability of the seal.The key components of the seal assembly are designed.According to the function of casing hanger and seal assembly running tool,the overall structure of running tool is determined.The connection form of casing hanger and seal assembly is lock block connection,including casing hanger lowering part,seal assembly lowering and pressing part.This paper analyzes the setting force of the locking sleeve,explores the relationship between the pressure acting on the setting surface of the locking sleeve and the total gravity of the drill pipe and the running tool,and analyzes the finite element of the locking sleeve at different setting angles by using Workbench,and obtains the optimal setting angle.Through the analysis of the sealing mechanism,the sealing reliability conditions are determined,and the stress model of the flange of the sealing assembly is established.Through the analysis of the normal deformation and the maximum contact stress,the influence of the structural parameters of the inner and outer flange of the sealing assembly on the contact stress is analyzed by the method of control variables.According to the working environment of the running tool,the mechanical analysis is carried out.The contact analysis of the casing hanger carrying unit,the contact analysis of the sealing assembly carrying unit and the strength analysis of the mandrel are carried out by using ANSYS finite element analysis software.The results show that the strength of each part meets the design requirements.By analyzing the different stress paths of lock block and retaining ring,the stress distribution characteristics are obtained.Analyzing the dynamics of the tool by using ADAMS simulation software,and the drill pipe drives the mandrel to rotate,which is converted into the axial translation of the drive body under the action of the arc groove,so as to realize the distortion and deformation of the mandrel and drill pipe in the process of the extension and retraction of the lock block of the casing hanging carrying unit and the lock block of the sealing assembly carrying unit.Analyzing the erosion and wear of seawater and cuttings on the backflow channel structure of the tool under different backflow channel structure parameters by using Fluent software.The results show that the change of angular velocity has little effect on the change of spindle torque,and the increase of angular velocity will not affect the performance of the spindle.On the premise of meeting the strength requirements,the larger the opening angle of the return channel of the tool is,the smaller the erosion wear is,and the erosion wear is the smallest when the return hole is not chamfered.