Development and Test of High-Strength Flexible Drill Rod
As the horizontal distance of ultrashort-radius drilling gradually extends,higher strength require-ments are constantly being put forward for the mechanical and sealing performance of the flexible drill rod.In order to solve the existing problems of flexible drill rod such as high structural strength requirements,short service life and difficult sealing,a high-strength flexible drill rod was developed.A ball pivot structure was used to connect the pup joints of the drill rod,allowing the joints to bend at a certain angle while transmitting torque and WOB.The finite element software was used to build a 3D finite element model for single joint of the flexible drill rod,and the stress classification method was used to check the structural strength of the flexible drill rod.Finally,laborato-ry test was conducted on the tensile,compressive and torsional structural strength and load-bearing sealing perform-ance of 3-section flexible drill rod.The test results show that when the developed high-strength flexible drill rod was loaded alone,it can still meet the strength requirements when subjected to an ultimate torque of 31 kN·m,a tensile load of 1 120 kN and a compressive load of 270 kN.The conclusions provide a theoretical basis for the de-velopment of high-strength flexible drill rods in oilfields.
flexible drill rodultrashort-radiusfinite element analysisequivalent stresslaboratory test
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