Study On The Compounding And Performance Of CO₂ Flooding Well Corrosion And Scale Inhibitor

In the process of CO2 flooding,CO2 injected into wellbore would dissolve in formation water to form carbonic acid,which can cause serious corrosion to wellbore pipes and downhole equipment.Besides,the scale also can easily form on downhole equipment due to the ions in the formation water.Corrosion and scaling of downhole equipment will cause blockage of oil well wellbore and equipment pipeline and damage equipment,which will result in low production of oil well and even scrapping and stopping production,and thus affecting the output of the whole oil field and bringing huge economic losses to the oil field.This has become a serious problem restricting the development of CO2 flooding oil recovery.Adding corrosion inhibitor and scale inhibitor is an effective way to fix the problem,but the efficiency depends on the specific environment.Each corrosion and scale inhibitor need to be evaluated according to the practical condition,because of synergies or antagonism.Therefore,this paper aims to provide a good corrosion and scale inhibitor for the corrosion and scaling of the wellbore produced by CO2 flooding in an oilfield.It mainly involves the following contents:(1)Quantum chemical calculation and molecular dynamics simulation was employed to study the molecule orbit distribution,global reactivity,local reactivity and adsorption behavior of various inhibitors.For 6 kinds of corrosion inhibitors and 5 kinds of scale inhibitors,the quantitative parameters,the local active sites and the energy parameters of adsorption reaction were then obtained.From the theoretical calculation point of view,the corrosion inhibitor isoquinoline quaternary ammonium salt(FIQ-C)and the scale inhibitor allyl polyethoxy sulfonate(APES)have the best performance.(2)Electrochemical methods and static scale inhibition test was performed to investigate the performance of corrosions inhibitors and scale inhibitors.The best performance corrosion inhibitor was selected from the experimental point of view.The isoquinoline quaternary ammonium salt(FIQ-C)scale inhibitor was allyl polyethoxy sulfonate(APES),and the influence of concentration and temperature on the performance of corrosion inhibitor and scale inhibitor was obtained.(3)Similarly,electrochemical test and static scale inhibition test were used to study the synergistic effect of compound reagents on corrosion and scale inhibition.The corrosion inhibition mechanism and scale inhibition mechanism of the compound corrosion and scale inhibitor on carbon steel were discussed,and The formulation of the composite corrosion and scale inhibitor was found to be a corrosion inhibitor(FIQ-C):scale inhibitor(APES)=2:1.(4)The static high temperature autoclave was used to study the protective effect of composite corrosion and scale inhibitor on the H-bar,N80 and P110 under different conditions under different conditions,and supplemented by SEM and EDS corrosion products.The corrosion inhibition performance of the composite corrosion and scale inhibitor under simulated conditions is good.The corrosion rate of the three steels after joining is less than 0.045 mm/a.The static scale inhibition test is used to compare the scale inhibitor and composite in the simulated formation aqueous solution.The scale inhibition rate of corrosion and scale inhibitors shows that the scale inhibition rate of composite corrosion and scale inhibitors is as high as 95.27%,and the corrosion inhibition performance and scale inhibition performance meet the industry standard requirements.The research results of this paper provide references for the corrosion protection and scale formation control of the tube in the wellbore of the CO2 flooding production well.Moreover,it has important theoretical significance and practical application value for solving the corrosion and scale formation problems in the CO2 flooding production well.