Author(s)

A. Pfennig & A. Kranzmann

Abstract

The role of pit corrosion needs to be considered to guarantee reliability and safety during the injection of compressed emission gasses – mainly containing CO2 – into deep geological layers (CCS-technology, Carbon Capture and Storage). Therefore, laboratory experiments were carried out under the distinct synthetic aquifer environment saturated with technical CO2 at a flow rate of 2 l/h found at the CCS-site at Ketzin, Germany. To determine the local corrosion behaviour, different pipe steels with 1% Cr 0.42% C (42CrMo4) and 13% Cr 0.46% C (X46Cr13) were compared. The samples were heat treated for up to 2 years and the reaction kinetics were determined. Pits were formed exclusively on the high chromium bearing steels. Pit heights and diameters were measured and a precipitation model was derived from the phases found within the complicated multilayer corrosion phases, such as siderite FeCO3 and goethite - FeOOH. Manganese and chromium carbides were found to be possible initial causes for the ongoing pit corrosion. Keywords: steel, pipeline, pit corrosion, CCS, CO2-injection, CO2-storage. 1 Introduction When engineering the geological CCS-site at Ketzin, Germany (CO2-SINK, CCS Carbon Capture and Storage [1, 2]), corrosion of the casing and injection pipe steels may become an issue when emission gasses are compressed from combustion processes into deep geological layers [3-10]. It is known from thermal energy production that the CO2-corrosion is sensitively dependent on alloy composition, the contamination of alloy and media, environmental conditions such as temperature, CO2 partial pressure, flow conditions and

Keywords

steel, pipeline, pit corrosion, CCS, CO2-injection, CO2-storage