Analysis On The Connection And Sealability Of Premium Connection With Alternating Loads

With the diiffculties of oil exploration increasing，the better performance of tubing isrequired for diiffcult exploration，the traditional API tubing cannot meet production needs inhostile conditions,premium connection are widely used because of its advantage on sealingand connection abilities.When the premium connection used in the deep well,it usually sufferfrom the load according to the condition. Its sealing and connection abilities will affect by thechanged load.Therefore this paper studied on the sealing and connection abilities of premiumconnection suffeirng from the changed load,the result is meaningful for the selection ofpremium connection, it can ensure the sealing and connection abilities of premium connectionin hostile well by the selected connection.In this paper, In order to obtaining a method to calculate the load on tubing (on premiumconnection), the bucking, the deformation and the load of tubing were analysed.The main typeof structure of premium connection were analysed.Taking the make-up torque and the changedload into consideration,the stress distribution on two types of premium connections werecalculated by finite element method,according to the stress distirbution and stress vairation,theconnection and sealing abilities of premium connection were analysed.The result shows thatthe chosen premium connections have expected performance on connection and sealing withmake-up torque. With the changed load, buttress type thread with pitch change can reduce peaktooth load and improve load distirbution,so the connection ability of buttress type thread withpitch change is better than buttress type thread without pitch change. With alternatingtension，conical seal achieve sealability with sealing pressure and big cantact area,tirple radiusseal can obtain localized high sealing pressure to ensure excellent sealability. With alternatingcompression, the value of sealing pressure on conical seal is lower than that on the tirpleradius seal，the value of sealing pressure on conical seal dropped with compression cycleincreased, the value of sealing pressure on tirple radius seal dropped in the ifrst compressioncycle and dropped little in other compression cycle.Based on the research above，take the problems of tubing in use into consideration andconsulted the related standard,write "the selection of premium connection" and "therecommended applcation of premium connection" to guarantee the distinguished performanceof premium connection in hostile well.