Corrosion Related Process Parameters

The nature of produced fluids vary from non-corrosive to severely corrosive. The corrosivity of produced fluids depend on not only their chemical composition, but also on the physical conditions, which is dictated by process parameters.

Temperature

The effect of temperature on electrochemical corrosion is similar to any other chemical reactions. Normally, higher temperature results in higher reaction rate, i.e., higher corrosion rate. The corrosion rate will be doubled with increase of 10oC (20oF). Most of corrosion inhibitors will loss their effectiveness at elevated temperature (say 200oC.

Pressure

The process pressure have greater influence on fluid corrosivity for the corrosion concern. For example, CO2 solubility increases against overall process pressure, which poses higher corrosion risk.

Cyclic loading and stress

This is typical important for upstream well production with long tubing strings and pumping rods. Wear occurs for these string rubbing against each others or against casing and packers.

Velocity

Erosion, abrasion and cavitation is the likely damage caused by excessive velocity. In practical, erosion can only be managed by slowing down the fluid velocity and excluding solids entrapment. NORSOK RP O501 has provided a quantitative tool to assess the potential erosion damage for upstream.

Cavitation effect is different to erosion. It occurs on the trialing surface of rapidly moving parts as the result of formation and collapse of vacuum  bubbles in the metal/liquid interface. Corrosion inhibitors and elastic coating (e.g. BelzonaTM) may help prevent the cavitation damage.

Leave a Comment

Your email address will not be published. Required fields are marked *