Wanying Liu

Inhibition effect of pomelo peel extract for N80 steel in 3.5% NaCl saturated with CO2 solution

Pomelo peel extract (PPE) has been evaluated as a corrosion inhibitor for N80 steel in 3.5% NaCl saturated with CO2 solution using weight loss measurements, Fourier transform infrared spectroscopy, potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM), scanning electrochemical microscopy (SECM) and quantum chemical calculations. The inhibition efficiency was found to increase with increasing PPE concentration. Potentiodynamic polarization measurements indicated that the PPE was a mixed type inhibitor. The adsorption of PPE obeyed the Langmuir adsorption isotherm and mainly the physical adsorption. The SECM and SEM studies were used to investigate adsorbed film on the N80 steel surface. Quantum chemical calculation indicated that the major component of the PPE has more tendencies for adsorption.

Repeated Impact Method and Devices to Simulate the Impact Fatigue Property of Drillstring

It is well known that drillstring failures are a pendent problem in drilling engineering, because of the fatigue accumulation caused by the low amplitude-repeated impact. In order to reveal the effect of low amplitude-repeated impact on the failure mechanism of the drillstring, a repeated impact method and instrument have been developed based on the Charpy impact method, by which a series of tests have been performed in the condition of non-corrosive medium and with H2S environment respective. Test results of non-corrosive medium environment indicates that, with the increase of single impact energy, the low amplitude-repeated impact resistance of drillstring decreases significantly; For H2S corrosion environment, the low amplitude-repeated impact resistances with H2S is much lower than that without H2S corrosion, and high strength material such as V-150 drillstring is more sensitive to H2S corrosion media. Furthermore, based on the experiment data, the accumulation fatigue model to predict the service life of the drillstring is developed, which could be used to predict the fatigue life. Research fruits are very vital to select a suitable rotational speed for drilling job and drillstring design.

Saccharum sinense bagasse extract as an effective corrosion inhibitor for J55 steel in 3.5% NaCl solution saturated with CO2

Purpose – The purpose of this paper is to test bagasse extract as an effective corrosion inhibitor. Design/methodology/approach – The bagasse was extracted without any toxic substance and was found to be effective for corrosion of J55 steel. Findings – The inhibition efficiency of bagasse was more than 90 per cent in 3.5 per cent NaCl solution saturated with CO2 for corrosion inhibition of J55 steel. Research limitations/implications – The inhibition effect of Saccharum sinense bagasse extract on the corrosion of J55 steel in 3.5 weight per cent NaCl saturated with CO2 solution was investigated by means of Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, polarization curve and scanning electron microscope. Practical implications – It can be used as low-cost corrosion inhibitor. Social implications – It is an environment-friendly corrosion inhibitor. Originality/value – This work is original and carried out in Southwest Petroleum University, China. This is not communicated a...