Factors Affecting CO2 Corrosion and Inhibitor Effectiveness Using Multi-phase Flowloop

A mini-flowloop was developed to study CO₂  corrosion and corrosion/erosion interactions, and to assess effectiveness of inhibitors under conditions that simulate multi-phase pipelines. The flowloop 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 flowloop were significantly different than 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. The  presence of  oil in brine solution increased the corrosion rates for both inhibited and uninhibited solutions. The CO₂ corrosion rate increased  slightly by 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 and 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 paper will also include results on tests conducted using inhibitors.