Socrates-B Steel Evaluation

Socrates-B also assists in determining the viability of carbon steels versus CRAs through a rigorous evaluation of general corrosion susceptibility of steels, with or without inhibition in the operating environment. This evaluation is, however, not applicable to stimulation acids, since all steel utilization in acidizing environments inherently involves use of corrosion inhibitors. The system determines a steel corrosion severity index, a measure of the overall corrosive severity of the environment. The Steel corrosivity model employed in Socrates-B is a subset of a more comprehensive prediction program (Predict™) developed at InterCorr.

In material selection it should be realized that conventional steels can be significantly more economical than CRAs in low severity environments or in greater severity environments when used with proper chemical inhibition. Therefore, before considering CRAs, it is important to first evaluate whether steels can be used in oilfield environments without being susceptible to sulfide stress cracking.

Socrates-B uses a large number of parameters to determine the steel corrosion severity index. The system uses the de Waard - Milliams' CO₂-based corrosion prediction model to obtain an initial assessment of corrosion severity in carbon steels in injected water environments without aeration. This estimate is modified to account for the effects of other factors such as temperature, H₂S, chlorides, velocity, oxygen and inhibition. Relevant parameters in steel evaluation include:

• Acid gas partial pressures
• Chlorides
• Maximum operating temperature
• pH
• Fluid velocity
• Aeration/chlorination
• Flow type
• Inhibition methods and efficiency