Study On The Corrosive And Tribological Behavior Of The Coating Of Several Thermo-chemical In The Oil-well Output Liquid

With the development of oil field production,the water content of oil-well output liquid is rising gradually and the problem of corrosion and partial friction of suck rod/tubing is getting worse.Furthermore,the interaction of corrosion and wear results great jeopardize to the oil field production,brings enormous direct and indirect economic losses.After studing the effect of sherardizing on the resistance of corrosion and wear, the tribological and corrosive properties of different surface treatment in oil-well output liquid of different water content are studied through electrochemical tests, tribological tests and microstructure analysis in this paper.The effects of temperature and time factors on the mechanism and performance of the coating morphology of N80 oil tube is investigated.The new surface protection technology of complex treatment and the friction pair being treated separately is devised.The main research content and achievement of the paper are described as below:1.The sherardizing of N80 oil tube had been processed in different temperature and time.The metallurgical structure had been observed.The influence of temperature and time on the structure and the growing parameter of sherardizing layer had been investigated.2.The nitriding and sherardizing complex treatment technology had been studied. The metallurgical structure had been observed.3.The corrosion behavior of several penetration layers had been studied.The Tafel curve of penetration layers of different chemical heat treatment had been measured and the corrosion potential and corrosion current density had been gainer. All the penetration layer's corrosion potential were below the N80 corrosion potential in oil-output liquid,which can be used as sacrificial anode substrate on the N80 to provide protection.The corrosion current density of the sherardizing is the smallest, having the most protective action to the N80 in the oil out-put liquid. 4.The efforts of sherardizing,nitriding and complex treatment on the friction and wear behavior of friction pair of N80 oil tube and GCr15 had been studied.The results showed that:The wear rate of sherardizing increased with the water content of oil out-put liquid and the wear rate at 75%water content was highest.Wear rate had a smaller change rate of water content.The friction coefficient and wear rate of nitriding samples was lower than sherardizing samples.But the wear rate of nitriding samples increased rapidly with water content.The friction coefficient and wear rate of the complex treatment samples was lower than sherardizing samples.N80 nitridizing + GCr15 sherardizing treatment could effectively reduce the friction coefficient of the friction pair and the wear rate of N80.This treatment had an equivalent protective effect with nitriding under low water content.Under high water content,this treatment had a more effective protective effect than nitriding.This treatment was particularly suitable for the protection of oil tube under high water content.