Effect of mercury on corrosion in production wells in the gulf of Thailand fields

Abstract

Studies of the corrosion of materials used for tubing in oil and gas production wells are important for cost minimization. In this work, 13% chromium staom;ess stee; amd :=80 carbpm stee; were se;ected fpr stidu bu o,,ersopm testing and potentiodynamic polarization techniques. Simulated produced water with the composition obtained from the Gulf of Thailand field was used as a corrosive solution in order to investigate the effect of mercury at various conditions of temperature, chloride concentration, CO2 partial pressure, and pH of the solution. Temperature was found to increase the corrosion reaction kinetically. Furthermore, chloride ions (0.1%NaCI-3.5%NaCI) and carbon dioxide were found to enhance the corrosion reaction by destroying the protective film, especially on 13Cr surface. Increasing the acidity of the solution causes the solution to be more aggressive due to the abundance of hydrogen ions to be consumed and generated H2 in the cathodic reaction, while the steel material becomes more metal ions in the solution. In addition, mercuric chloride, as the representative of the mercury species in the production wells, with a concentration between 0-12 ppm does not cause any effect to both materials. Moreover, there is no synergistic effect between trace amount of mercury and temperature (30C-60C) or carbon dioxide. However, with a mercury concentration higher than 100 ppm, the corrosion rate was increased due to the invreasing in reduction process.