Research on effects of residual polymer on the corrosion and scaling of the oilfield produced water

The effects of residual polymer on corrosion and scaling of the oilfield produced water were studied through gravimetric method combined with calcium carbonate precipitation method and conventional electrochemical etching method. The results show that the residual polymer with lower concentrations can accelerates the Ca²⁺ to the scale in the form of precipitation slightly, mainly increased the amount of hard scale attached to the vessel wall, little effect to the soft scale in the produced water. When the residual polymer concentration is greater than 200 mg/L, the polymer chelating solubilization to calcium is in the ascendant, and gradually reduced the scaling tendency of the solution. The residual polymer has corrosion inhibition, the corrosion rate can reach 59.22% with polymer concentration of 50 mg/L, it has a role of chelating the corroded sewage and dispersing the solid suspension. There is a synergy effect between the residual polymer and the field antiscaling agent, corrosion inhibitor, preventing scale and corrosion mitigation is better than that of excluding polymer sewage, it is of positive significance for sewage reinjection.