CHARACTERIZATION OF CORRODED TUBING UNDER CO2 ENVIRONMENT

SUMMARY: Carbon dioxide corrosion is one of the most important problems, in the Oil and Gas Industry, for production tubing and line pipes. The main types of corrosion are:- Generalized corrosion (Loss of weight).- Mesa-type corrosion (Localized corrosion under form of mesetas).- Localized corrosion. The main factors affecting the corrosion resistance are metallurgical (microstructure, heat treatment and presence of some elements like Chromium) and operational (flow rate temperature and partial pressure of CO2 in the corrosive environment). Two field experiences are presented, representing two different situations of the used materials. The first is relevant to C-Mn and C-Mn-B steels, the second to 1 % Cr steels with different microstructures. Better results were obtained with 1 % Cr s eel (J55), normalized and with perlite-ferrite microstructure. For higher grades of tubing (like N80 or C95), the quenched and tempered (Q + T) materials are the only possibility; thus, it’ necessary to explore the role of different alloy additions like Cr, Cu, Ni to enhance the resistance CO2 corrosion. KEY WORDS: CO2 corrosion. tubing, Carbon Manganese steel, Chromium steel, ferrite-perlite microstructure, sweet corrosion, tempered mart nsite, quenching and tempering