OPTIMAL SELECTION OF MATERIALS FOR SEA WATER INJECTION SYSTEMS TESTING IN DEOXYGENATED SEA WATER

摘要

Seawater injection systems represent a tough working environment for oilfield down hole tubing. To ensure adequate corrosion control of the equipment, system operation conditions and water quality need to be optimized. For downstream from the director the oxygen level, flow velocity and residual chlorine are critical parameters. In the present paper the effect of these factors has been studied in test loop for two C-steels. The testing was performed at oxygen levels from 20 to 200 ppb oxygen and with a flow velocity up to 15 m/s. The corrosion rate of C-steels for a system without residual chlorine was lower by a factor of 10 or more than could be predicted from the traditional hydrodynamic modelling. In those calculations, the corrosion rate has dependence on the flow velocity to the power of about 0.9. While for a system with 0.5 ppm residual chlorine the corrosion rate was related to the flow velocity to the power of 1.9 at the oxygen levels of 20 to 50ppb. Semi empirical modelling of corrosion rates is discussed.