Analysis Of Sealing Performance Of BGT1 Oil Pipe

The loading condition of downhole pipe string is complicated.And the joint part of pipe string is mainly affected by axial force,internal pressure,bending moment and makeup torque.These loads have an impact on the connection performance and sealing performance of special threaded joints.Even though the special threaded joints are used in deep wells with high temperature and pressure,if the joint torque value control is not appropriate,the problems of pipe string leakage and casing pressure rise are easy to appear.Among the many factors,statistics showed that 80%of the lose efficacy occurs at the threaded joints of tubing and casing coupling.The makeup torque value has a direct effect on the occurrence of failure.If the value of torque is too small,it will cause release and leakage,and if the value of torque is too large,it will cause the phenomenon of sticking.Therefore,the reasonable torque value can effectively prevent the occurrence of failure.In this paper,study on the sealing performance of special threaded presented.Three BG95SS88.9 9.53BGT1 special thread oil pipe joints are selected.The experiment is the main part,and the simulation is the supplement to carry on the thorough research,and the complete scientific research system is obtained by combining theory and experiment,which is of guiding significance for practical application in the field,so as to reduce safety accidents and improve economic benefits of oilfield production.The main tasks are as follows:(1)The research status for casing and tubing connections has been investigated from the aspects of theory,finite element analysis and test.The main problems for premium connections have been analyzed and the research train and main contents in this paper has been put forward.(2)Finite element analysis was performed through the ABAQUS.The sealing conditions are simulated under the conditions of maximum torque,optimum torque,intermediate moment and minimum torque and the sealing performance of different torques is calculated by simulating the ultimate tensile pressure of 80%and 100%.(3)A set of airtight experimental devices was developed and the corresponding operating procedures were formulated.Nitrogen generators,hydraulic devices,pneumatic devices,laboratory equipment,testing tools,torque adjusters,rubber tensioners,experimental tools and venues are available.(4)At the first stage of the experiment,a large number of experiments were carried out mainly on the sealing performance of the high-performance screw connection for the torque.The pressure test was carried out under the conditions of maximum torque,optimal torque and minimum torque,respectively,at 70MPa and 90MPa,and six sets of effective experimental data were obtained.(5)The second stage of the experiment,mainly for the impact of tensile and compressive loads on the performance of tubing thread sealing performance.Under the 70t tensile and compressive load,the experiment was carried out three times,nine times,thirty times after repeated tension and compression,and then the experiment was carried out under the optimal torque and minimum torque conditions.Six effective experiments were obtained in this group.(6)At the third stage of the experiment,the experiment was carried out mainly on repeated shackles to study the change of the sealing performance of the column after the high-performance threaded tubing was repeatedly shackled.In this group of experiments,the experiment was carried out under the pressure of 90 MPa after repeated shackles,and two sets of experiments were carried out for the two sets of oil pipes.In short,this paper mainly conducts in-depth research on the factors that can be controlled by the field,such as the torque size and repeated shackles,and obtains the best buckle torque.Therefore,the research of this paper not only has important theoretical significance and academic value,but also has great engineering significance and broad application prospects.