Research Andapplication On Laser Surface Modification Of Sucker Rod And Tubing

Sucker rod pump oil production is one of the most commonly used mechanical oilextraction method, tubing and sucker have the relative motion in the scope of stroke, the oilwell inclination or sucker rods and tubing bending will cause the tube and rod eccentric wear,which seriously affect the major oil fields crude oil production, because of eccentric wear andcorrosion increase the oil well maintenance workload proportion has also increasedsignificantly. Conventional measures preventing eccentric wear mainly use the centralizer,Coating anticorrosive wear-resisting coating, etc.but they all have obvious shortcomings. Inorder to solve the problem of tube and rod eccentric wear, This article through the pumpingtubing rod surface laser hardening process and improve the wear and corrosion properties ofthe tubing and coupling, extend the service life of the pumping tubing and rod.Based on a large number of trials, grasp the tubing inner coating, the technology of laserphase on oil tube inner surface and coupling of cladding programming formula. The tubinginner wall laser processing power is1500W, using circular Ф3mm light spot, line speed of3850mm/min, screw pitch9mm, can obtain phase transformation hardening zone with thethickness of0.4mm, the macro-hardness is HRC41.00,we can know by metallographicanalysis, laser transformation tubing divided into the melting zone, transformation hardeningarea, the heat affected zone and the substrate. Microstructure of melting zone is lathmartensite and retained austenite; the organization of phase transformation hardening zone isblack fine needle-like martensite and retained austenite; the organization of heat affected zoneis tempered martensite, retained austenite, ferrite, and carbides. By tensile testing we canknow its mechanical strength and plasticity has change.The tensile strength from ordinarytubing550MPa reach to580MPa，The yield strength from ordinary tubing828.1MPa to861.3MPa. By micro-electrochemical test, we can know ordinary tubing corrosion currentdensity is7×10-5A/cm2, and the laser phase transformation zone corrosion current density is 4×10-5A/cm2, the tubing corrosion resistant performance had improved.In order to combine the test results with the actual production, through the research onoil well conditions, we use5%NaCl solution analog simulate the corrosive environment, anddo the grinding test. Selection of laser surface modification pumping tubing rod wear the leastamount of friction pair combination. Selection the laser surface modification pipe and rodwhich friction pair combination is the least amount of abrasion loss. The test results show that:6mm pitch change tubing have the hightest hardness, coupling were badly fray;12mm pitchchange tubing through a short period of grinding phase, laser transformation hardening zoneoff;9mm pitch change tubing with the Ni45cladding collar as a friction pair combination, theamount of abrasion loss at a low level, improve the ability of preventing eccentric wear.Through the study of the above test, we can successful get the surface of tube and suckerrod be handled by laser technique, and use in GLL17X6oil well process of production,through the application of on-site follow-up survey, we can know the tubing and rod behandled by laser can effectively prevent partial wear, Shorten the maintenance period,improve production efficiency.