A mini-flowloop was developed to study CO2 corrosion and corrosion/erosion interactions, and to
assess the effectiveness of inhibitors under conditions that simulate multi-phase pipelines. The miniflowloop
was used to study the effect of testing time, steel chemistry, velocity, temperature, fluid
chemistry, sand and inhibitors on corrosion rates. The measured corrosion rates in inhibited and
uninhibited solutions using the mini-flowloop were significantly different from those measured using
other methods such as the Greene cell method. The effect of adding 1/2% Cr to the steel did not
improve its CO2 corrosion resistance as has been claimed by some suppliers. The presence of oil in a
brine solution increased the corrosion rates for both inhibited and uninhibited solutions. The CO2
corrosion rate increased slightly with increasing flow rate suggesting that the corrosion mechanism is
partially diffusion controlled. At high flow rates, the presence of sand enhanced corrosion of steel in
both uninhibited and inhibited solutions while at low flow rates sand had no effect on corrosion rates in
uninhibited solutions, but it had a profound effect on the rates in inhibited solutions. The water soluble
inhibitor was effective in controlling uniform corrosion, but failed to control pitting corrosion for tests
conducted in 100% water solution. In 90% water-10% oil solution, the effectiveness of the inhibitor
decreased and the corrosion rate increased compared to the oil-free case, but pitting was not observed.
When a de-emulsifier was added to a solution inhibited by the water soluble inhibitor, corrosion rate
increased dramatically. The oil soluble inhibitor was not successful in controlling pitting corrosion at low
flow rates or uniform corrosion at high flowrates.
Keywords: Corrosion, pipeline, integrity management, Inhibitors, sand production, CO2.