Papers by Keyword: CO₂ Corrosion

Abstract: In the process of oil and gas extraction, N80 steel is used as a common tubing material. CO₂ corrosion has become one of the most dangerous problems in its entire life cycle. In this paper, the conditions of different temperatures (90-220 °C) and CO₂ partial pressure (0.2-3 MPa) were selected, and the dynamic rotating high-temperature autoclave was used to simulate N80 steel corrosion in formation water environments. The results showed that the corrosion rate of N80 steel gradually decreased with the increase of temperature, and the corrosion rate was the lowest at 150 °C. In addition to this, with the increase of CO₂ partial pressure, the corrosion rate first increased and then decreased. The corrosion rate was the highest when the CO₂ partial pressure was 0.8 MPa. Through surface analysis techniques (SEM and XRD) and electrochemical tests, it was found that the corrosion resistance of N80 under high temperature and high pressure is closely related to the corrosion product film (FeCO₃). The compactness of FeCO₃ product film determines the corrosion characteristics of the matrix.

Abstract: The influence of temperature, flow rate, PH value, and oxygen content on the corrosion law in the carbon dioxide salt solution of J55 oil casing was investigated by the corrosion weight loss method. The results showed that with the increase of temperature, the corrosion rate of J55 steel first increased and then decreased and the corrosion rate reached the maximum at 100°C. The corrosion rate was closely related to the formation of corrosion products. The increase of the flow rate speeded up the transfer rate of the corrosive medium to the metal surface and hindered the formation of FeCO₃ on the metal surface. The corrosion rate was significantly higher than the corrosion rate under static conditions, and as the flow rate increased, the corrosion rate of J55 steel increased accordingly. The increase of the pH value gradually reduced the concentration of hydrogen ions, and cathodic reaction of hydrogen ion depolarization during metal corrosion process was inhibited, and the tendency to form an oxidizing protective film on the surface of carbon steel increased, thereby reducing the corrosion rate of metals. With the increase of oxygen content, there were both hydrogen evolution reaction of CO₂ and oxygen absorption reaction caused by O₂ in the cathode process. The corrosion rate of J55 steel gradually increased, and at the same oxygen content, the higher the carbon dioxide content, the greater the corrosion rate is.

Abstract: Inhibitor is a chemical compound which commonly used to control corrosion in a tank or a pipelines. Organic inhibitor recently developed because of the availability and the ability to act like commercial inhibitor. The performance of mixed inhibitor was studied on St 41 carbon steel immersed in NaCl solution containing CO₂ gas. Research parameter used were pH 4 and 6, rotation speed of 150 and 250 rpm, with mixed inhibitor volume ratio of 1 (imidazoline) : 2 (paracetamol), 1:1, also 2:1. The Weight loss measurement, isotherm adsorption calculation, FTIR, and XRD measurement have also been done. Based on weight loss test, the highest inhibitor efficiency was 61.412 % at pH 6, 150 rpm, with inhibitor volume ratio of 2:1, adsorption isotherm calculation indicate the adsorption mechanism of the mixed inhibitor is physical adsorption. Tafel test result showed the tendency of inhibitor worked anodically. The FTIR spectrum result found functional group of N-H from the inhibitor precipitated on the metal surface after ten days of immersion Based on the EIS result, there was an increase value of polarization resistance value and decrease on CPE (constant phase element) value. While X – ray diffraction (XRD) result from the volume ratio of 1:2 confirm the CO₂ corrosion product FeCO₃ and Fe₂O₃ formed on metal surface. With volume ratio of 2:1 mixed inhibitor, it was confirmed that iron nitride (Fe₂₄N₁₀) compound was formed on steel surface because of the chemisorption reaction between Fe and nitrogen atom from pyridine at the imidazoline inhibitor. The inhibition mechanism was physisorption for entire parameters, based on calculation of Langmuir adsorption theorem.

Abstract: Understanding inner corrosion property of casing steel is fundamental to safe and economic exploitation of oil & gas. In this present work, a series of corrosion tests were conducted on 3%Cr coupons derived from 9-5/8” casing. Analyses of weight loss, product morphology and composition were carried out, to investigate the corrosion behaviors caused by sweet CO₂. Analysis on the weight loss showed that, with an increment of temperature from 45°C to 105°C, the corrosion rate of 3%Cr coupon firstly ascends and then arrives to the maximum at 65°C. SEM analysis demonstrated the formation of a compact corrosion product layer on the specimen surface. While increasing the exposed time increases, the corrosion rate gradually descends. The main compositions of corrosion product are Fe-Cr and Cr₅O₁₂, which can effective hinder corrosion reaction in the CO₂ environment.

Abstract: Corrosion of carbon steel in CO₂ saturated NaCl solution contains the formation of FeCO₃, as a corrosion product. The protective property of the formed FeCO₃ scale layer to corrosion in brine solutions containing CO₂ was established as the possible cause of the corrosion rate decrease above 60 °C. In this study, formation of nanoscale FeCO₃ film as a corrosion product of X52 carbon steel in CO₂-Saturated 3% NaCl solution was investigated. Result showed that corrosion rate decreased after precipitation and formation of protective FeCO₃ film in high temperature and high bulk solution pH.

Abstract: The performance of SAE 1010, API K55 and API N80 steels were evaluated in terms of resistance to corrosion with the use of two CO₂-saturated saline solutions (NaCl and CaCl₂, both at the concentration of 0.5 M) and wet supercritical CO₂ at a temperature of 90°C under 15 MPa for 07 days. Mass loss tests were performed to determine corrosion rates and the films of corrosion product evaluated by scanning electron microscopy and potentiodynamic polarization technique. Lower corrosion rates were obtained in a wet supercritical CO₂ medium. The degree of protection offered by corrosion products films depended not only on the steel but also on the corrosive medium and kind of salt present.

Abstract: This work evaluate the protective characteristic of the CO₂ corrosion product layers formed on the surface of two types of steels, API 5L X80 used for transportation of oil and gas, and API 5CT P110 used for case tubing and pipe for oil drilling.Electrochemistry evaluations and morphological characterization of the obtained layer were performed. These steels were exposed to a brine solution containing 3% wt of NaCl, in a pressurized autoclave with 55 bar of CO₂ and total pressure of 75 bar at different temperatures (25, 50 and 75°C) and immersion times (7, 15, 21 and 30 days). The corrosion rate was determined by mass loss tests and electrochemical techniques, such as Linear Polarization Resistance and Electrochemical Impedance Spectroscopy. Characteristics of the corrosion product layer such as thickness, morphology, and chemical composition were analyzed by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-Ray diffraction (XRD). The corrosion rate decreases with the increase of the immersion time and temperature, and the lower rate of corrosion was obtained for 75°C after 30 days of immersion, for both steels

Abstract: CO₂ corrosion comprises the majority of material damage, which leads to shutdown in petroleum industries. This phenomenon depends on parameters such as pH and temperature. Monitoring and recording these parameters help industries minimize waste in terms of time and financial resources. The insufficiency of tools for this purpose is noticeable. This study proposed an potentiometric IrO₂–pH microelectrode design in conjuction with a Ag/AgCl refrence electrode for real-time corrosion monitoring that can be used in various industries. Electrodeposition approach was used in the fabrication of a pH sensor. Electrochemical experiments were conducted to characterize the IrO₂–pH sensor as well as monitor the pH on a metal surface in conjunction with the fabrication of a pH microelectrode-designed system. Results show that the proposed pH sensor design can be used for real-time corrosion monitoring by surface pH measurement.

Abstract: The impact of CO₂ partial pressure ,fluid producing rate and corrosive medium on the CO₂ corrosion regularity of N80 steel and the inhibition efficiency of imidazoline inhibitor are investigated respectively through simulation of the actual working environment in the mined-out space of mechanical oil production wells by using high temperature and pressure reactor. According to the results, the corrosion rate of metals increases with CO₂ partial pressure but the inhibition efficiency of the inhibitor is hardly affected when CO₂ partial pressure in the scope of 1~3MPa. The increase of the fluid producing rate will accelerate the corrosion of metals and the inhibition efficiency will decline. With corrosion inhibitor applied, metals corrode slower in the liquid phase than in the gas in the initial stage, but latterly the corrosion rate is gradually higher than that in the gas phase.

Abstract: The corrosion behavior of X80 pipeline steel with quinoline inhibitor in NACE solution (CO₂ environment) at different temperature/different pH/different inhibitor volume fraction was researched using electrochemical test methods. The results show that as the temperature increases from 30°C to 50°C, CO₂ corrosion of X80 pipeline steel becomes much severer and the inhibition efficiency decreases first and then increases. As the pH increases from 4.15 to 5.76, the inhibition efficiency increases. When the volume fraction of inhibitor ranges from 2% to 4%, the inhibition efficiency increases, and particularly this is more obvious from 2% to 3%.