Evaluation of Corrosion Behavior of 20 Steel Ground Pipeline in Multiple Thermal Fluids

The ground pipeline for multiple thermal fluids in well area X of Xinjiang Oilfield was dynamically monitored by corrosion coupon. The representative failure pipe section was selected according to the monitoring results. The wall thickness measurement, microstructure observation, corrosion rate calculation, chemical composition analysis and corrosion product analysis were carried out for the obtained failed pipe section, in order to synthetically evaluate damage degree and corrosion rule of the failed pipe section. The corrosion mechanism of pipeline was verified by indoor simulated corrosion test. The results show that 20 steel ground pipeline was seriously corroded in multiple thermal fluids. Bainite and Weidner structures were observed in the microstructure of the failed pipe section surface, and the carbon content of the pipeline was reduced. Carbon dioxide corrosion occurred first, and then oxygen corrosion occurred in the pipeline. Oxygen in the reactants had the greatest effect on the corrosion rate of the pipeline.