Abstract
| Improving corrosion resistance of oilfield drilling equipment is crucial to the drilling effectiveness, environmental contamination, and operation safety. In this study, inhibition effects of three eco-friendly fatty acid-based inhibitors, Polyethylene glycol-2 oleamide (PEG-2 oleamide), Glycerol myristate (GM) and Glycerol linoleate (GL), in emulsion-based fluids against CO2 corrosion of carbon steel were investigated at room temperature. The corrosion inhibitors were characterized by Fourier transform infrared (FT-IR) spectroscopy and CHNS-O analysis. The corrosion resistance of steels was studied by electrochemical tests including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectrophotometer (XPS) were employed to study surface morphology and the chemical composition of layer adsorbed on the metal surface. The study demonstrates remarkable performance of the three green inhibitors especially PEG-2 oleamide, which shows an inhibition efficiency of 99.7 %. The high inhibition efficiencies were consequence of blocking effect of corrosive ions to reach metal surface by forming a corrosion-protective layer. First-principles calculations and molecular dynamics simulation reveal chemical bonding between the inhibitors and iron surface, and stronger intermolecular attraction in the adsorbed film resulting from PEG-2 oleamide, which renders the PEG-2 oleamide–induced film particularly durable. |
Keywords
Fatty acid-based green inhibitors, drilling fluids, Carbon steel, CO2 corrosion,
