| Summary: | In HPHT environments, the mechanism of CO2 corrosion faces a challenge
as an effect of chemical-physical reactions on the metal surface. The
presence of other elements in the CO2 system complicates corrosion
behavior. To provide a realistic mechanism for corrosion process, some
corrosion prediction models have developed software using fundamental
theories such as electrochemical reactions and thermodynamics theories.
Existing methods to predict corrosion rate models in HPHT environments
have shown reasonable results. This paper reviews software of corrosion
predictions which calculate corrosion rate based on mechanistic theories
that study effects of H2S, acetic acid (HAc) concentrations, shear stress, pH
in temperature from 25oC – 100oC and pressure from 1–10 bar. From the
simulation, corrosion rate increased significantly in the high pressure CO2
environment. Corrosion rate at pH 4 increased to 30 mm/y at a temperature
from 15oC to 90oC. While at pH 8 corrosion rate reached 4 mm/y. This
lower corrosion rate indicated a tendency for deposits formation at higher
pH. Corrosion rate behaves in a different mechanism at high temperatures.
The corrosion rate decreased to 4 mm/y when the temperature increased to
more than 90oC. Effects H2S gas and HAc were identified to increase
corrosion rate. Both elements provide extra cathodic reaction and create
limiting current density in the cathodic reaction process based on
polarization sweep models. However, the polarization graph calculated
using corrosion models could not display passive behavior in the anodic
polarization process. Thus, further, improvement should be considered.
From the data calculation, it can be shown that corrosion prediction
software can predict corrosion rate in HPHT conditions.
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