Corrosion Behavior of N80 Steel in High Temperature Multi-component Thermal Fluid for Thick Oil Exploitation

Corrosion behavior of N80 steel in high temperature multi-component thermal fluid was studied by weight loss method in autoclave and scanning electron microscopy. The results showed that in the medium with high pressure carbon dioxide and slight oxygen in the temperature range 40~280 ℃, there were two corrosion rate peaks of the steel at 60 ℃ and 180 ℃ respectively. The corrosion characteristics were concerned with the variation of corrosion product mainly composed of ferrous carbonate and oxide. In the multi-component thermal fluid, the static corrosion rate of the steel reached the maximum, and in dynamic state the flow rate only showed a slight effect on the corrosion rates. So the high dynamic corrosion is dependent on the oxygen mass-transfer control. Oxygen increases the CO2 corrosion of steel N80 at high temperatures obviously.