Investigation on electrochemicl behavior of modified Al anodes in tidal environment of shengli oilfield

Abstract

Al anode was widely used for cathodic protection of metal in marine environment due to its high capacitance and current efficiency. However, it was prone to passivation in alternating dry-wet environments. At present, relevant scholars had carried out research on new Al anodes in the alternating dry-wet environment of atmosphere or ocean. However, there were few reports on Al anodes in the soil alternating dry-wet environment. Therefore, focusing on the tidal environment of Shengli oilfield, the performance of three types of modified Al anodes was determined by corrosion and electrochemical test. The results showed that compared with Al-2 and Al-3 anodes, the corrosion product layer on the surface of Al-1 anode showed a broken, loose, poor compactness characteristic, while the general corrosion rate (4.329 mm/a) was larger and the maximum pit depth (27 μm) was smaller on the 30th day of immersion experiment. Meanwhile, the open-circuit potential of Al-1 anode (E OCP = −1.09 V) was more negative, and the corrosion current density (I corr = 5.34 × 10−3 μA m−2) was larger, while the capacitance (Q-Y 0 and C dl) was larger and the resistance (R p and R ct) was smaller. In conclusion, the Al-1 anode showed a better performance in tidal environment of Shengli oilfield.