The corrosion resistance of casing pipes used in the shalegas production systems

摘要

Natural gas industry is one of the world's largest industries. Its revenues are large, as are the costs of providing consumers with the energy they need. One of the most problematic issues for constructors at this branch is corrosion of materials used as casing pipes. The carbon steels K55 and N80 are frequently used as casing pipes. This work includes corrosion rate and mor-phology of the corrosion layer formed on the surface of investigated materials. The carbon steels were exposed for 96 hours to simulated fracturing fluids saturated with C02 or C02 and H2S. The exposition was done in autoclaves under elevated temperature and specified pres-sure. The corrosion rate was calculated based on the gravimetric measurements. The layer of corrosion products was investigated by means of scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX) and X-ray diffraction spectroscopy (XRD). The obser-vation of the corrosion layer on the cross-section revealed the double-layered structure of av-erage thickness around 30-50 urn. The differences in the morphology and corrosion rates of carbon steels were revealed.