Corrosion is a common problem in the oil and gas industry, which reduces the lifetime of oilfield equipment. An extensive internal corrosion in the e.g. multiphase export pipelines, topside pipes or in the wells often leads to replacement of used materials to corrosion resistant alloys. In the case of wells, workovers are performed, when the well integrity is at risk due to corrosion.

To prevent corrosion, e.g. corrosion inhibitors, H2S and O2 scavengers or biocides can be used. However, despite of using such mitigation techniques, extensive corrosion in wells is still observed.

Why does corrosion occur

The conditions present in the wells are complex and the severity of corrosion depends on various environmental (e.g. CO2/H2S/O2, seawater fraction, temperature, pressure, liquid flow velocity, stresses etc.) and material variables (e.g. chemical composition, microstructure, surface roughness). Additionally, the formation of scales (e.g. CaCO3) and the techniques used to remove them (chemical and/or mechanical) might also contribute to increased corrosion rates. Therefore, the corrosion observed in the wells often involves several mechanisms, which makes it difficult to predict and define which of them lead to loss of well integrity. Further, it is also challenging to monitor corrosion processes in the wells especially when the localized corrosion occurs underneath the formed scale.

DHRTC research

The research in this area is focused on defining corrosion mechanisms and governing parameters responsible for enhanced corrosion rates in the wells. Further, the work is to be concentrated on developing appropriate predictive tools, appropriate mitigation techniques to minimize the corrosion risk as well as reliable monitoring technologies. This in turn will reduce the operational cost of the oil production and decrease the operational risk.