Preparation And Application Of New-type High Temperature Acidification Corrosion Inhibitors Used In Hydrochloric Acid

With the development of oil and gas fields into the middle-late stages,the depth of the wells and the bottom-hole temperature are increasing,which lead to higher performance requirements for the corrosion inhibitors used in acidizing treatment.At present,the acidification corrosion inhibitors on the market only be applied to the acidizing treatment of90?~120?,which lose efficacy when the temperature is 140? or higher because of some shortcomings such as easy coking and weak adsorption.In this paper,a mannich compound called MM and a quaternary ammonium salt compound called KJ were synthesized as the main agent of acidification inhibitor.The best synthesis process was obtained by single factor screening experiment and orthogonal experiment.The products were purified and characterized.A mannich high temperature acidification inhibitor called MMPD and a quaternary ammonium salt high temperature acidification inhibitor called KJPD were obtained by the study of synergistic effect among the main agent of the inhibitor,dispersant and synergist.The physicochemical properties,solubility and dispersibility,corrosion inhibition performance and core damage performance of MMPD and KJPD were evaluated according to SY/T 5405-1996 "Test method and evaluation index of corrosion inhibitor for acidification".The results showed that the dissolution and dispersibility of the two inhibitors in the acid solution reached the standard of the first grade.The effective inhibitory temperature of MMPD was 140?,and that of the KJPD reached 160?.The core damages of both inhibitors were weak with the damage ratios under 25%.The mechanism of the corrosion inhibitors was studied by electrochemistry,monomer action analysis,surface analysis and adsorption thermodynamics.The adsorption models were established.The results showed that MMPD is a kind of mixed type corrosion inhibitor which evenly suppresses the anode and cathode.KJPD is a kind of mixed type corrosion inhibitor which predominantly suppresses the anode.In the beginning when the inhititors adding into acid solution,rapidly adsorption of alkynol mainly slow down the corrosion rate of the steel.Then the synergistic effect of the adsorption film of main agent and synergist provides comprehensive and stable protection for the steel.The inhibition performance of both inhibitors was mainly supplied by the geometric adsorption effection,the adsorption process is exothermic,spontaneous and to meet the Langmuir adsorption isothermal.