Corrosion behavior of oil tube steels under conditions of multiphase flow saturated with super-critical carbon dioxide

A 34.4-MPa rotary autoclave was used to evaluate the corrosion behavior of J55, N80 and P110 pipe steels under the conditions of multiphase flow saturated super-critical carbon dioxide (SC-CO2). Among the three tube steels, J55 steel exhibited the best corrosion resistance. CO2 corrosion rate decreased with the development of immersion time due to the thickening of the corrosion scale. The flow structure of multiphase mixtures was governed by crude oil-to-water ratios, which influenced the CO2 corrosion rate significantly. Under the condition of this work, 50% water cut in the mixture was deduced to be the switch point of the flow structure from water-in-oil to oil-in-water, and the flow structure completely became into oil-in-water state while the water cut in the mixture was over 50%. The schematic diagram of the flow structure was also discussed. (C) 2003 Elsevier B.V. All rights reserved.