Influence of compressive stress on corrosion of premium connection casing material

Key words:  casing  tubing  premium connection  carbon steel  stainless steel  compressive stress  corrosion

Abstract:

The fixture was design to simulate material enduring compressive stress, and the fixture was put in high temperature autoclave, and the corrosion rates of two kinds of casing materials(carbon steel and stainless steel) enduring compressive stress were tested in H₂S and CO₂ and CL-water solution. The corrosion electrochemical behaviors of the steel casing were tested under compressive stress. The results show that the corrosion morphology of oil casing is pitting in the test medium. The compressive stress accelerates the corrosion of petroleum casing steel. When the compressive stress is less than the half of the material yield strength, material corrosion is not obvious, and the corrosion rate increases quickly when compressive stress is greater than the half of the yield strength. The compressive stress design values of oil casing and tubing premium connection sealing surface and torque shoulder should not exceed the half of yield strength of material.