Research On Stress Analysis And Sealing Performance Of N80 API Tubing Coupling

Oil tubing is an important component in the process of oil production,while the threads between tubing and couplings play a crucial role in keeping pipes in good situations.In the actual mining process,tubing accidents may be caused by many uncertain factors.It is investigated that 80% of the accidents occur at the junction of the tubing and couplings.Thread accidents such as tripping and corrosion frequently occur in the production process.Tubing is apt to be threaded off because of thread corrosion,leading to reduction in oil production.In order to ensure the efficiency of oil recovery,improve tubing and coupling life and reduce the number and duration of workover,the new anti-corrosion coupling application is imperative.According to the elastic plastic mechanical properties of thick cylinder theory and combined with the related formulas of API Spec 5B and API Spec 5CT,theoretical analysis of tubing and collar button thread is implemented to obtain the force and contact pressure.The optimum torque of API N80 4? not upset tubing is calculated.Using ABAQUS finite element analysis software to create coupling model of N80 API 4 not upset tubing,with reasonable meshing and boundary conditions,the situations 1 to 3 ring buckle is simulated.The simulation results show that the best buckle ring number for 2 laps after extraction of tubing and coupling thread stress and contact pressure.The market commonly used sealing material classification and related parameters are reviewed.Due to the advantages of rubber,such as flexibility and resistance to corrosion,rubber is selected as the sealing structure.It reduce probability of thread corrosion,prolong pipeline and the service life of the hoop.According to tubing and collar best buckle torque,API coupling model is modified by embedding the rubber structure.The situation of button 2 laps of the tubing is analyzed and coupling screw thread stress situation is obtained.It is illustrated that the thread has not been damaged.Buckling 2 rings can ensure that the rubber and the hose connector are in the surplus state,effectively preventing crude oil and the thread contact.With the analysis and calculation of tubing and collar of the well in 3000 m depth,the internal pressure and axial force are set reasonable and accurate.Comparing the simulation results between buckle 2 laps and deducted 3 laps,stress and contact pressure vary for different well depth.A tubing joints connecting hoop stress may lead to tubing in dangerous conditions.After simulation for actual condition,the results show that the tubing and collar thread in the normal working state and the rubber tubing joint contact pressure is far greater than the oil pressure.It is proved that the new anti-corrosion collar design is reasonable,greatly improving the sealing performance.