The Influence Of Molecular Structure Of Imidazoline Derivatives On Inhibition Performance In H₂S/CO₂ Environment

With the increased demand for oil and gas resources in China, more and more acid oil fields have been under drilling. However, H2S/CO2 corrosion phenomenon of oil/gas production and transmission has become a prominent problem. Therefore how to control this corrosion is drawn attention of the researchers around the world. Among the inhibition of H2S/CO2 corrosion methods, adding corrosion inhibitor is a simple and effective method. In this paper, varieties of imidazoline derivatives were synthesized and the respective structures were tested by infrared spectroscopy. The influence of functional groups of imidazoline derivatives on inhibition performance was investigated in detail by the method of dynamic weight loss test, AFM, contact angle measurement, quantum chemistry calculation and molecular dynamics simulation.1.Hydrophobic property and adsorption capacity of IM-18、 IM-18D、IM-22 and IM-22D were investigated in dynamic H2S/CO2 environment by contact angle testing and AFM force curve. The results showed that IM-18D and IM-22D performed the enhanced hydrophobic property and adsorption capacity, which accorded well with the results of the dynamic weight loss test. It revealed that hydrophobic chain with double bond improved the inhibition performance of imidazoline derivatives. The molecular dynamics simulation also proved that the imidazoline derivatives with double bond possessed stronger adsorption energy.2.The inhibition performance of imidazoline derivatives IM-I、 IM-Q、QM-I、QM-Q was investigated by polarization curve, electrochemical impedance spectroscopy, contact angle, AFM force curve and dynamic weight loss test. The results showed that the hydrophobic property of the imidazoline derivatives was reinforced by introducing hydrophobic chain with the hydroxyl group;the adhesion force of imidazoline derivatives was enhanced by modifying hydrophilic chain with the hydroxyl group; the introduction of the hydroxyl of imidazoline derivatives improved the inhibitive performance. Meanwhile, the molecular dynamics simulation also proved that imidazoline derivatives with the hydroxyl possessed stronger adsorption energy.3. The effect of inhibition performance on the concentration of imidazoline inhibitor with ricinoleic acid group was investigated by dynamic weight loss, polarization curve and electrochemical impedance spectroscopy. It was found that inhibitive efficiency increased as the concentration of imidazoline derivative rising and the preferred additional density was 100 mg·L-1. The contact angle and AFM force curve also showed that under the situation of 100 mg·L-1, the inhibitive film tended to cover the substrate uniformly, therefore the performance of the particular imidazoline derivative reached a steady state.