Research of Sediments in Assessing the Causes of Corrosion at Gas Facilities

Abstract

Various methods of corrosion monitoring are used to control the aggressiveness of operating conditions of oil and gas facilities and ensure their safe and reliable operation. One of them is the analysis of resulting corrosion products and other sediments and precipitates to obtain data on their composition. The article presents the results of a study of sediments in determining the mechanisms and causes of the origin of the corrosion processes with the subsequent development of measures to eliminate the factors of their evolution. The composition of sediments being formed at gas complex facilities is studied. Inorganic compounds and elemental composition are analyzed using X-ray diffraction and scanning electron microscopy. It is revealed that the sediments contain elemental sulfur, indicating the presence of dangerous sulfur-containing compounds (for example, H₂S) in the system. Using IR spectroscopy and gas chromatography–mass spectrometry, the organic components of the sediments being formed during the preparation of a corrosion inhibitor solution in methanol are determined. It is shown that the reason for their formation is the presence of petroleum hydrocarbons in the solution. When analyzing the sediments formed inside the water transport pipe, it is found that they include iron oxides and hydroxides. At the same time, in places of a through defect on the outer surface of the pipe, corrosion products consisting of Fe(II) or Fe(III) hydroxides with layers of anions and water molecules are formed—the so-called “green rust.” Such sediments being unstable under operating conditions are not capable of providing protection of the steel surface from corrosion. The results obtained can be used for corrosion monitoring at gas facilities to identify corrosion factors affecting the formation of sediments and precipitates.