| Nowadays, oil field development has come to the mid-late period and with the risingquantity of water content, the sucker rods’ working environment is becoming worse andworse, corrosion of sucker rod is becoming more and more serious. In order to solve thisproblem, we will spray the polyurea coatings on the sucker, the purpose of which is toimprove the sucker’s performance of corrosion resistance.In this paper, according to the characteristics of various components and raw materials andMDI isomers and faculties polyurea degree of influence on the performance of the elastomer,screening for polyurea material which has better corrosion resistance and wear resistance, andit suits to the down-hole environment, and produce the polyurea coatings with anticorrosionand wear resistance that they are suitable for sucker rod. And according to the characteristicsof sucker rod spraying, designing a kind of suitable for polyurea equipment. The polyureacoatings modified with organosilicone of20CrMo steel were prepared by spraying. Thebinding power and hardness of polyurea coatings were analyzed through adhesive powertester and micro hardness tester. The corrosion resistance performance of polyurea coatingswere tested by immersion test and the slow strain rate test (SSRT). Then using corrosionexperiment under the high temperature and high pressure conditions, scanning electronmicroscope and electron microprobe analysis were employed to study how CO2partialpressure affects corrosion behavior of epoxy-polyester primer and polyurea topcoat compositecoatings in3.5%NaCl solutions. The results showed that:(1) During the modulation process of polyurea formulations, the the appropriate amount ofpropylene carbonate vinegar (PC) was added to the component A, which could not onlyreduce the viscosity but also improve the effect of mixing and atomization and the mechanicalproperties of the material.When designing for the best formulation of the R component, lowmolecular weight chain extender which has an appropriate reaction rate should be considered.The sprayed polyurea elastomer gel time can be pre-controlled by adjusting the amount ofchain extender in the formulations of polyurea.(2) Due to the waste of paint and other shortcomings of the existing polyurea sprayingequipment at high temperature and high pressure, we design an anti-corrosion spraying equipment dedicated to the slender rod, such as the sucker rod, at room temperature andatmospheric pressure. The spraying equipment can improve the coating efficiency and save alot of polyurea coatings. The mechanical automatic operation and continuous operation can beachieved. Additionally, it can improve the working environment and be conducive to thehealth of the construction workers.(3) The corrosion rate reduces approximately one magnitude and corrosion resistance isimproved. Furthermore, the fracture times delay6.5h roughly, and the life of steel increasessignificantly.(4) The epoxy-polyester primer and polyurea topcoat composite coatings could improve thecorrosion resisting property of substrate effectively after the corrosion experiment under thehigh temperature and high pressure conditions; the corrosion of the material near the scratchwas much more serious than other places. But the macroscopic attachment of the coating andsubstrate is good; shielding effect of polyurea topcoat could prohibit the permeation anderosion of corrosive fluid, which retarded the corrosion; the corrosion rate of the polyureatopcoat increases as the increase of partial pressure of CO2. |
PDF Full Text Request