Deposition of petroleum heavy organic compounds on a low carbon steel tubing

Reduction of petroleum wells production is often observed and related to th e presence of solid deposits adhered on the internal wall of the tubing. A piece of tubing with organic material adhered on its surface was recovered from a Mexican southeastern region well. fts composition and morphology was studied applying scanning electron microscopy with X-ray energy dispersion spectroscopy (SEM-EDXS), X-ray diffraction (XRD) and reflection Fourier Tr ansform Infrared Spectroscopy (FT-IRS). High-condensed hydrocarbons with hy droxyl and carboxyl functional groups and 6.4 wt% total sulfur were found. The adhered-material morphology suggests vitreous solid structure usually i dentified in polycyclic aromatic compounds. Iron (II, III) oxides and nonst oichiometric sulfides are present; the last, as a corrosion product obtaine d in petroleum with low H2S concentration. Pyrrhotite (Fe1-x S), which exhi bits a nonstoichiometric structure, was reported as the active phase of iro n oxide catalysts in hydrogen interchange processes.