Study Of The Technology Of Corrosion And Anti-Corrosion To The Pipelines In Daniudi Gas Field

The paper made the study of corrosion and anti-corrosion aiming at the corrosion of the downhole casing in Daniudi Gas Field.Firstly,the corrosion environment of the downhole casing in Daniudi Gas Field was studied. It was consisted that studying the quality of the reservoir water to make the contents of mineral ions and mineral degrees clear,as well as analysing the composition of the recovery natural gas. Futhermore, corrosion coupon experiment was made and the SEM was used to analyze the mechanical properties of the different materials’surface. According to the results of the experiments and analysis,the paper obtained the mechanism,the factors and the conditions of corrosion of the downhole casing in Daniudi Gas Field.By corrosion coupon experiment and the corrosion theory of CO2,the paper made the experimental study and theoretical prediction to the inner corrosion of the gas pipelines in Daniudi Gas Field.Based on the results,it showed that the corrosion were all mild and the results of the theory prediction were much larger than the actual. All these telled us the study of the corrosion and anti-corrosion technology must take experiments of the special conditions. Based on it, the theory could be perfected.In light of the compenent analysis of the corrosion products as well as the results of the corrosion coupon experiment,the paper got a instructive conclusion:the CO2 and the saline comprehensively lead to the corrosion of the downhole casing in Daniudi Gas Field.Then, simulating the real condition of the Daniudi Gas Field, the paer made screening tests and combination tests to salt corrosion inhibitor and CO2 corrosion inhibitor.The results showed that all these corrosion inhibitor couldn’t get the satisfied inhibition effect.On it,the paper made experiments to synthesis the new corrosion inhibitor.On the analysis of the theory of corrosion in the downhole casing of Daniudi Gas Field, by Mannick reaction the paer synthesised the new corrosion inhibitor——ZA taking the free acetone, formaldehyde, ethylene diamine and cyclohexanone and analysed it by IR spectroscopy.Furthermore,the paper evaluated the properties of ZA.The result shows that the scale inhibiting rate was above 90%.Then,the paper studied the mechanism of ZA.In this paper, the CO2 corrosion inhibitor ZA had the benefie of simple synthesis conditions, low synthesis temperature, and it was say to obtain the raw materials. When the ZA and HS-3 was combinated, the slow eclipse effect meets the scene requirements.Finally, the paer made the field trial uses of ZA. When it used methanol, antifoulant and so on,ZA could be compatible with these chemical reagents. By studying the replenishment of corrosion inhibitor, thepaper also defined the replenishment procedure,equipments and the way to replenish.All these lay a foundation to the field application.