For a given production system, the corrosion mitigation philosophy is usually established based on the fluid properties and the operating parameters pre-identified within the Basis of Design (BOD). Information in the BOD comes from reservoir simulation, process/flow modeling, and thermodynamic/compositional fluid analyses. These data have limited accuracy and a wide variability throughout the field life. Very often and due to capital expenditure (CapEx) constraints, most of production facilities primarily utilize carbon steel lines with corrosion mitigation provided by injection of chemical inhibitors. When using carbon steel and inhibition, a successful operation requires active corrosion monitoring to keep tabs on effectiveness of the chemical inhibition program. The monitoring program is a key to proactively identify new corrosion mechanisms surfacing during the field operation. Due to the wide variety of operating conditions, it is not practical to run laboratory corrosion tests simulating every production scenario. Most of the corrosion predictions rely heavily on the laboratory test results; however, the tests have limitations and may not precisely cover all of the corrosion mechanisms in predicting field performance. Depending on new mechanisms identified by the corrosion monitoring program, corrective actions are usually taken. These actions may include additional chemical treatments and mechanical systems such as pigging to bring the corrosion under control. This paper discusses some of the interesting corrosion mechanisms that have emerged in production systems due to changes in operating conditions during field operations. Corrosion monitoring data with fluid analyses, flow modeling, and additional laboratory testing have been effectively used to understand the corrosion mechanism and develop solutions for control. This work focuses on internal corrosion control of carbon steel in production and transportation lines with single or multiphase flow.
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