Study On Corrosion And Protection Measures Of Gathering Pipeline In Carbonamide Composite Flooding Process

In order to improve the oil recovery rate,a series of enhanced oil recovery technology is adopted,which not only brings huge profits,but also makes the corrosion problem of gathering pipeline increasingly prominent.In this paper,through the indoor simulation experiment,the corrosion affect on the gathering pipeline during carbon amide composite flooding process is explored,the materials are optimized,the corrosion inhibitor with good effect and the best concentration are selected,and finally the feasibility and economy of the corrosion prevention measures are compared and analyzed,the main conclusions are as follows:The results of weightless corrosion test show that in the simulated carbonamide composite flooding environment,as the temperature and CO₂ partial pressure increase,the corrosion rate of 20G carbon steel and 316L stainless steel increases first,and at a temperature of 80℃,the CO₂ partial pressure reaches 0.5MPa,it gradually decreased.The corrosion rate of20G and 316L with the increase of water content and oxygen content,the corrosion resistance is getting worse and worse.The corrosion morphology of 20G carbon steel is uneven and comprehensive corrosion,and the main corrosion product is FeCO₃、Fe₂O₃.Because 316L stainless steel is passivated in the corrosive medium,the protective effect of the passivation film makes its corrosion rate lower than that of carbon steel,and the corrosion morphology is slight pitting.The electrochemical test results show that the corrosion reaction of 20G carbon steel and316L stainless steel decreases with increasing temperature,the charge transfer resistance Rct value decreases,and the corrosion resistance deteriorates,but after 80℃,its electrochemical corrosion tendency begins to decrease.Electrochemical corrosion kinetic resistance increases,and corrosion resistance becomes better.The results of inhibition performance test show that at 80℃,3#inhibitor has the best inhibition effect on 20G carbon steel,and the best concentration is 450 ppm,2#and 1#inhibitor respectively show poor inhibitor effect.Electrochemical analysis showed that the three kinds of inhibitors were anode inhibitors mainly.Compared the results with and without inhibitor,the charge transfer resistance Rct increased,indicating that the inhibitor molecules adsorbed on the metal surface gradually formed a protective film,inhibited the corrosion reaction of the metal electrode.