A High Temperature Corrosion Inhibitor for Use at 200℃

inhibitor for use in acidification fluids has been developed to deal with corrosion to downhole tubular goods by acids at 200℃. The synthesis of this corrosion inhibitor involved the use of Mannich base quaternary ammonium salt as the main additive, an alkynol derivative and an inorganic salt as the synergists, and an alcohol solvent and a dispersant as the auxiliary additives. The introduction of the alkynol derivative (to replace propynol) into the corrosion inhibitor can minimize the toxicity of the corrosion inhibitor and render it good solubility and dispersity. Laboratory evaluation of the corrosion inhibitor using high temperature high pressure dynamic corrosion evaluation method showed that a fluid containing 15%HCl has corrosion rate less than 60 g/(m²·h) at 200℃ if the fluid was treated with 5.5% corrosion inhibitor. If the concentration of the HCl was increased to 20%, the corrosion rate was less than 70 g/(m²·h). The 15% HCl acid fluid has good compatibility with other additives. Electrochemical corrosion test showed that an acid treated with the corrosion inhibitor has electric current density of 6.07×10^-6 A/cm². The corrosion inhibition efficiency of the corrosion inhibitor decreases with increase in the amount of the main additive and the synergists used, and increases with the increase of the acid concentration and the amount of the thickening agent used. Electrochemical evaluation of the corrosion inhibitor showed that addition of the corrosion inhibitor reduced the electric current density of the acid fluid; when added into the acid to a certain concentration, the corrosion inhibition efficiency will not be further improved.