An experimental study on the internal corrosion of a subsea multiphase pipeline

Abstract

Based on the actual operational parameters of a subsea multiphase pipeline, an experimental study on the internal corrosion of a subsea multiphase pipeline was conducted in a dynamic, high-temperature autoclave, which had a similar environment to an actual field environment, using the partial pressure of CO₂ (PCO2), velocity of the corrosion medium, temperature, corrosion time, and corrosion inhibitor as variables. The results show that CO₂ resulted in severe localized corrosion and that the corrosion rate increased as the P_CO2 and velocity increased; the corrosion rate first increased and then decreased with increasing temperature. The corrosion rate peaked at approximately 65 °C and then decreased continuously afterwards; the corrosion rate decreased as the duration of the experimental period increased. Under the operational conditions of the selected subsea pipeline, localized corrosion caused by CO₂ was still the primary corrosion risk. Several types of corrosion inhibitors could inhibit the occurrence of localized corrosion for a short time period; however, most corrosion inhibitors could not completely inhibit localized corrosion.

Keywords

Subsea pipeline / Internal corrosion / Experiment / Corrosion inhibitor

Acknowledgment

This paper is a project Supported by the Special Fund of China's Central Government for the Development of Local Colleges and Universities——the Project of National First-level Discipline in Oil and Gas Engineering.

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