Corrosion And Scale Inhibition Properties Of Imidazoline Cinnamate Derivatives

In the development of oil and gas fields,which will lead to corrosion and scaling of oil well pipelines,water injection well pipelines and gathering and transportation pipelines,resulting in significant economic losses.As a kind of chemical agent with both corrosion inhibition and scale inhibition effect,corrosion and scale inhibitor has been widely applied in oil and gas field stimulation process.In this paper,imidazoline intermediate(ID)was synthesized from cinnamic acid and diethylenetriamine,and the structure was characterized by IR and GC-MS.The imidazoline derivative CAID was synthesized by Mannich reaction using ID,formaldehyde and phosphorous acid,and the optimal synthesis conditions(3.5 h,120℃)were screened by the corrosion inhibition effect of the product on N80 carbon steel.The synthesized product was characterized by IR and 1HNMR.PASP/ID,a polymeric imidazoline derivative polyaspartic acid graft copolymer,was synthesized with ID,polyepoxysuccinimide(PSI)and 2 mol/L NaOH solution,screening by orthogonal experiment the synthesis conditions(temperature is 45℃,time is 12 h and pH=11),and the structure is characterized by IR and 1HNMR.The CAID and PASP/ID corrosion inhibition were evaluated and analyzed in the simulated oilfield water and 15%hydrochloric acid by static weight loss method,electrochemical method,atomic absorption spectrophotometry,surface analysis(digital microscope,SEM,EDS)and quantum computational chemistry.Static weight loss experiment results show that CAID and PASP/ID a have good corrosion inhibition effect in simulated oilfield water.When the addition amount is 800 mg/L,the corrosion rate is less than 0.076 mm/a.With the increase of corrosion system temperature,both corrosion inhibition efficiencies have declined to some extent,and the CAID has a smaller change range and better thermal stability.In 15%hydrochloric acid corrosion solution,the PASP/ID corrosion inhibition effect is better than CAID at low concentration.The corrosion inhibition rate of CAID and PASP/ID decreased with the increase of temperature.The corrosion inhibition rate of CAID and PASP/ID decreased with the increase of temperature.With the increase of temperature,the corrosion inhibition efficiency of the CAID and PASP/ID decreased significantly,and the downward trend of PASP/ID addition was more obvious than that of the added CAID.When the addition amount rate reaches 0.5 wt.%,the CAID corrosion inhibition effect is excellent,and it can reach the field application standard of the oilfield.The PASP/ID corrosion inhibition effect is ordinary and does not meet the oilfield application standard.Atomic absorption spectrophotometry shows that in the simulated oilfield water corrosive medium,the corrosion products of N80 carbon steel are mainly hardly soluble oxides and hydroxides,and its sink the bottom of the corrosion solution.In the corrosion medium of 15%hydrochloric acid,the corrosion products of N80 carbon steel is Fe2+ and Fe2+ chelate compounds are dissolved in the corrosion solution.Electrochemical experiments show that both CAID and PASP/ID can reduce the corrosion current density.In the brine corrosive medium,CAID and PASP/ID mainly inhibited the cathodic reaction of N80 carbon steel;in 15%hydrochloric acid,they are mixed corrosion inhibitors,which have certain inhibitory effects on the cathode and anode,and the addition of imidazoline derivatives does not change the corrosion mechanism.Quantum chemical calculation results show that both imidazoline derivatives are adsorbed on the surface of N80 carbon steel by electron donating effect,and the CAID corrosion inhibition efficiency is theoretically superior to PASP/ID.The results of SEM and EDS analysis show that both CAID and PASP/ID can be adsorbed on the surface of N80 carbon steel to inhibit corrosion.The calcium carbonate and calcium sulfate scale inhibition performance and scale inhibition mechanism of CAID and PASP/ID were investigated by static scale inhibition method,SEM and XRD.Static scale inhibition experiments show that when the concentration of CAID and PASP/ID were 300 mg/L,the inhibition efficiency of CaSO4 scale was 67.3%and 90.1%.When the concentration of CAID was 300 mg/L,the inhibition efficiency of CaCO3 scale was 49.2%.The maximum inhibition efficiency of CaCO3 scale was 71.2%obtained at 200 mg/L of PASP/ID.Increasing the concentration of CAID has a positive effect on the performance of CaCO3 and CaSO4 scales.Increasing the concentration of PASP/ID can increase the performance of CaSO4 scale,and the performance of CaCO3 scale increases first and then decreases.The effect of temperature on the performance of CaCO3 and CaSO4 scales was investigated.The performance of CAID inhibited CaSO4 scale decreased and the performance of CAID inhibited CaCO3 scale hardly effected with the increase of temperature.In addition,the incubation time has a certain influence on the scale inhibition performance of both,and the scale inhibition performance of CAID and PASP/ID decreases with the increase of the incubation time.The results of SEM experiments show that the addition of two imidazoline derivatives can change the crystal morphology of CaCO3 and CaSO4.The XRD results also show that the crystal structure of CaCO3 and CaSO4 changes,which indicates that both imidazoline derivatives cause the lattice distortion of CaCO3 and CaSO4 scale.