The Influence of Flow Rate on Corrosion Behavior of X65 Carbon Steel in Water-saturated Supercritical CO_2/H_2S System

摘要

The influence of flow rate on corrosion behavior of X65 carbon steel in water-saturated supercritical CO_2 phase containing 1000 ppmv H_2S impurity was studied at 35 ℃ and 8 MPa from 0 m/s to 1.5 m/s. Weight loss tests showed that the general corrosion rate reached maximum at the flow rate of 1 m/s and then decreased with flow rate to 1.5 m/s. Turtle pattern corrosion morphology was observed on the sample surface when the flow rate exceeded 1 m/s. The corrosion product mainly consisted of FeCO_3 and FeS, and the average size of spherical corrosion product changed with flow rate. Besides, the percentage composition of FeS presented the same change trend as the average size of spherical corrosion product. In supercritical CO_2 phase, wall shear stress was not big enough to cause mechanical damage on corrosion film but can affect the formation process and the characteristics of the corrosion film of X65 carbon steel.