Study on the Corrosion Behavior of 22Cr Steel in HCl/HAc Solution at Ultra-High Temperature

Abstract

Acidizing is an effective and routine measure for oil and gas extraction, but acid liquor can cause severe corrosion to oil and gas pipeline columns, especially in high-temperature reservoirs. The high-temperature wells are often acidified by a combination of organic acids and hydrochloric acid to reduce the corrosion of oil and gas pipeline columns caused by acid. In order to effectively reduce the corrosion of oil and gas pipeline columns caused by acidizing, the high-temperature(200 ℃) corrosion behavior of 22Cr steel in various acidic solutions was studied through electrochemical experiments and weight loss experiments. The surface corrosion morphology of steel samples in different systems was observed using a scanning electron microscope(SEM). An X-ray energy dispersive spectrometer(EDS) was used to analyzed the elemental composition and distribution on the surfaces of samples before and after corrosion. X-ray diffraction(XRD) was utilized to determine the composition of corrosion products on the surface of samples. Results showed that 22Cr steel had good corrosion resistance in different concentrations of acetic acid solution, but the increase in Cl- concentration in the acetic acid solution accelerated the corrosion of 22Cr steel. 22Cr steel was severely corroded in low-concentration HCl solution. The composite acid liquor system, composed of low concentration HCl and low concentration acetic acid, was found to have a synergistic effect on the corrosion of 22Cr steel and accelerated the corrosion of 22Cr steel. At 200 ℃, the composite inhibitor, composed of corrosion inhibitor QASE and corrosion inhibitor synergist Sb2O3, was effectively able to inhibit the corrosion of 22Cr steel in the hydrochloric acid and acetic acid composite acid solution.

Keywords

• 22cr steel; ultra-high temperature; corrosion behavior; synergistic corrosion; composite acid