Corrosion Detection of Carbon Steel in Water/Oil Two Phases Environment by Electrochemical Noise Analysis

摘要

The aim of this paper is to demonstrate the effectiveness of the Electrochemical Noise Analysis todetect the onset of corrosion phenomena in a very high resistivity medium. Tests were carried outon carbon steel electrodes immersed in a water/mineral oil two phases environment with highconcentration of CO_2, different aqueous/organic phase ratio, sulphide content between 0 and0.5 g/1 and pH between 1 and 5.The evolution of corrosion phenomena were followed by collecting current and potential noisebetween three nominally identical electrodes.The noise data were analysed in the time and in the frequency domain.In spite of a great loss of sensitivity of the method with respect to tests performed in aqueoussolution, the data indicate a good agreement between the standard deviations and the power levelof Power Spectra Density (PSD) of current and potential noise signals and corrosion rates bymeans of weight loss. The values of the PSD slope, indicate the form of corrosion. The effect ofwater/oil ratio, sulphide concentration and pH on the corrosion rate was determined. Finally twomethods to increase the sensitivity of the Electrochemical Noise are proposed.