Synthesis And Performance Study Of CO₂ Corrosion Inhibitor In Zhanjiang Gas Field

Carbon dioxide(CO2)is often used as a component of natural gas or petroleum associated gas present in the oil and gas.CO2 have highly corrosive on steel after it dissolved in water.Due to the rich mineral in the stratum water,CO2 corrosion often coexist with salt corrosion.The paper made the study of anti-corrosion aiming at solving the corrosion in ZhanJiang Gas Field.Based on the metal corrosion mechanism in the salt water saturated with carbon dioxide,a new Mannich base corrosion inhibitor which has a good corrosion performance were designed and synthesized.According to molecular structure design,a series of inhibitors(BMe,AGE,BYS,BLS)were synthesized.By the static weight loss experiments,the best corrosion inhibitor of the four inhibitors is BLS which synthesized by acetophenone,salicylaldehyde and diethylenetriamine.Through single factor experiment method and the orthogonal experiment optimization,the best condition for synthesizing was confirmed as follows:the reaction temperature of 85?,the reaction time of 7h,the mole ratio of salicylaldehyde,acetophenone and diethylenetriamine are 2.2:2.2:1.0,and acetophenone and diethylenetriamine was dropwised together.The corrosion rate was 0.007796 mm/a using the best conditions for synthesizing BLS.Then,modified the BLS by an other Mannich reaction to get the product D-BLS which is a multiple mannich base and its corrosion rate is 0.005681 mm/a,the mole ratio of salicylaldehyde,formaldehyde,acetophenone,diethylenetriamine are 2:1:3:1.FT-IR and 1HNMR were used for the qualitative analysis about BLS's structural characterization.By the electrochemical experiments in 3%NaCl salt water saturated with CO2,it proved that BLS is an inhibitory cathode reaction-based mixed inhibitor.And the thermogravimetric analysis showed that BLS and D-BLS have good thermal stability,at 200? conditions,the weight loss rate of 8.0%,5.9%,respectively.Then,the solubility,the tendency of emulsification and the compatibility with the antifouling and clay stabilizer were tested by experiments.Based on the experimental and theoretical study about the adsorption of inhibitor BLS,it showed that BLS could automatic adsorption and follow the Langmuir adsorption isotherm equation on the steel sheet.BLS's inhibition performance was revalidated by scanning electron microscopy and energy dispersive spectrometer.Then,the global reactivity indices,such as frontier orbital energy,hardness and dipole moment,were investigated via quantum chemical calculations to analyze the molecular reactivity.It showed that BLS has a low energy gap and it is easily adsorbed on the surface of steel sheet.