SYNERGISTIC COMBINATION OF SODIUM SILICATE AND ORTHOPHOSPHATE FOR CONTROLLING PIPELINE STEEL CORROSION IN WATER CONTAINING OXYGEN AND BIOCIDE AT THE DIFFERENT TEMPERATURES

摘要

Synergistic effect of sodium silicate and sodium orthophosphate on the pipeline steel corrosion inhibition in water containing oxygen and biocide at temperature from 30°C to 140°C has been investigated. Sodium silicate was added in concentration from 0 to 1000 ppm by weight. The sodium orthophosphate concentration ranged from 0 to 500 ppm by weight and the concentration of commercially biocide "bio" ranged from 0 to 200 ppm by weight. The steel samples were evaluated by weight loss measurement after 4, 8, 12, 24, 48, 72 and 96 hours of immersion at 30°C, and after 4 hours of immersion at 60°C, 100°C and 140°C. A Solatron 1280Z was used for the electrochemical measurements: the potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Based on the experiment results, corrosion inhibition mechanism is discussed and optional synergistic effect of the corrosion inhibitors have been proposed for preparation of packer fluid at oil and gas wells.