CO2-containing Environment Research Articles

Unraveling the corrosion behavior and corrosion scale evolution of N80 steel in high-temperature CO2 environment: The role of flow regimes

During CO2 transportation and storage, metal equipment such as oilfield pipelines suffers from severe CO2 corrosion, especially in harsh downhole injection equipment. In this study, we investigated the corrosion behavior of oil well tubing in a high-temperature, high-pressure (HTHP) CO2-containing environment. The evolution of the corrosion scale was also examined under different flow regimes. The results reveal a lower corrosion rate at 150 °C compared to 80 °C under different flow regimes, with localized corrosion intensifying as temperature and rotational speeds (vrs) increase. The temperature also induces the corrosion scale conversion of aragonite-type CaCO3 (80 °C) to calcite-type CaCO3 (150 °C). Specifically, the variation of the corrosion rate and the corrosion scale evolution can be attributed to the vortices within the reactor. The intact vortex cells enhance mass transfer while also promoting nucleation and growth of CaCO3. However, when vrs exceeds the critical Reynolds number, the vortex cells are disrupted, resulting in viscous dissipation and a reduced corrosion rate.

Importance of the autoclave testing parameters on the initial stage of corrosion under CO2-containing geothermal environments

Autoclave corrosion testing has been used for many years; however, few have studied the effect of its shortcomings on the formation of corrosion products and corrosion behaviour. In particular, understanding of these effects under high temperature and high pressure (HTHP) is rare. In this study, we highlighted the important parameters such as heating periods, flow rates and volume-to-surface ratios influencing carbon steel corrosion in the early stages. Especially, characterisation and protection behaviour of corrosion products associated with corrosion behaviour in the heating stage under the geothermal CO2-containing environment were systematically studied via mass loss, in-situ electrochemistry and surface analysis techniques. The roles of pCO2, volume-to-surface ratio and flow rate influence the formation of the corrosion products in the early stage are also evaluated.

Multiscale performance and environmental impact assessment of slag and Portland blended cement for optimum carbonation curing

This article presents an investigation into the potential use of ground granulated blast-furnace slag (addressed as Slag cement or ‘SC’) as a replacement to Ordinary Portland Cement (OPC) in hybrid (carbonation and hydration) cured cement-based materials. To investigate the effects of carbonation on mechanical performances and microstructures, 0 %–100 % OPC was replaced with slag cement (SC). Thermogravimetric analysis (TGA) and Fourier transformed infrared (FTIR) spectra were utilized to investigate the carbonation reaction extent, rate, and microstructural phase formations. Slag cement was found to improve the efficiency and rate of carbonation. This study revealed that a minimum of 72 h of carbonation in a CO2-containing environment yields better mechanical performance compared to the traditional curing method. Specifically, the incorporation of 72 h of carbonation curing was observed to increase the strength of concrete up to 30 % after 28 days of total curing duration (carbonation and hydration). The chloride permeability of the carbonation cured samples was observed to reduce by 80 % due to the addition of SC. Finally, it was observed that, the carbonated concrete sample with slag has nearly 60 % lower global warming potential compared to the carbonated and non-carbonated concrete sample with 100 % OPC binder.

In situ SR-XRD analysis of corrosion product formation during ‘pseudo-passivation’ of carbon steel in CO2-containing aqueous environments

In situ Synchrotron Radiation X-ray Diffraction (SR-XRD) is employed to follow the evolution of corrosion products on X65 carbon steel in a CO2-containing aqueous environment (80 °C, pH 6.3–7.3). A custom-designed flow cell is used to follow the real-time concomitant changes in electrochemical behaviour and corrosion product growth during stages of both natural and potentiodynamically driven ‘pseudo-passivation’. We show that no detectable crystalline magnetite (Fe3O4) phase forms during ‘pseudo-passivation’ across all conditions studied. Furthermore, the results suggest the significant ennoblement observed during ‘pseudo-passivation’ in these experiments can be strongly related to the accumulation of iron carbonate (FeCO3) on the steel surface.

Developing two amino acid derivatives as high-efficient corrosion inhibitors for carbon steel in the CO2-containing environment

During the oil and gas exploitation, the corrosion of carbon steel pipes causes great economic loss, heavy casualties, environmental pollution, and waste of resources. The development of highly efficient and stable corrosion inhibitors is of great significance for the corrosion protection of carbon steel in oil and gas exploitation. L-cysteine is widespread in various plants (e.g. onion, cauliflower, and cabbage sprout). As a corrosion inhibitor, it usually has low inhibitive efficiency in most corrosive environment. Chemical modification is the most efficient method to solve this issue. Herein, two synthetic amino acid derivatives (2-phenylthiazolidine-4-carboxylic acid (PTCA) and 2-(thiophen-2-yl)thiazolidine-4-carboxylic acid (TTCA)) were investigated as high-efficient corrosion inhibitors to deal with the corrosion issue of carbon steel in the CO2-containing environment. The anti-corrosion property of the amino acid derivatives was investigated by electrochemical experiment, surface technique and theoretical calculations. The electrochemical results show that PTCA and TTCA present high corrosion inhibition efficiencies at the concentration of 0.8 mM: PTCA (99.1%) and TTCA (99.3%). The inhibitive mechanism of PTCA and TTCA on carbon steel surface is revealed by theoretical calculations. It is found that the PTCA and TTCA adsorb at the steel/solution interface by forming Fe-O bonds. Compared to PTCA, TTCA exhibits stronger adsorption on carbon steel surface by forming shorter Fe-O bonds with a more negative adsorption energy, which accounts for the better inhibitive performance of TTCA.

Permeating hydrogen generated from the elemental sulfur corrosion of low carbon steel

Permeating hydrogen generated from the elemental sulfur corrosion of low carbon steel was investigated using a double cell system and its effect on the mechanical properties of steel was also discussed. Results show that elemental sulfur corrosion of low carbon steel is accompanied by significant hydrogen permeation, e.g., permeating hydrogen current reaches 12.3 μA/cm2 in CO2-containing environment at 80 °C. The hydrogen permeation process are greatly affected by the structure and composition of the corrosion product, the environmental temperature and gas composition. This permeating hydrogen enhances the brittleness of the low carbon steel and tends to cause hydrogen-induced cracking.

Влияние режимов термической обработки на механические свойства и стойкость сталей нефтепромысловых труб в модельной СО2-содержащей среде

The influence of heat processing conditions on the experimental steel resistance to carbon dioxide corrosion for Fe-V-Si alloying system in a model CO2-containing operating environment, is viewed. Findings of the alloy structural, mechanical and corrosion characteristics, giving that it had new constitution, can be of great importance in the development of new steel grades for the production of oilfield casing and tubular goods, resistant to CO2-containing operating environment

Electrochemical behavior of 2205 duplex stainless steel in simulated solution containing high concentration Cl− and saturated CO2 at different temperatures

2205 duplex stainless steel (DSS) has good corrosion resistance due to its typical duplex organization, but the increasingly harsh CO2-containing oil and gas environment leads to different degrees of corrosion, especially pitting corrosion, which seriously threatens the safety and reliability of oil and gas development. In this paper, the effect of temperature on the corrosion behavior of 2205 DSS in a simulated solution containing 100 g/L Cl− and saturated CO2 was investigated with immersion tests and electrochemical tests and combined with characterization techniques such as laser confocal microscopy and X-ray photoelectron spectroscopy. The results show that the average critical pitting temperature of 2205 DSS was 66.9 °C. When the temperature was higher than 66.9 °C, the pitting breakdown potential, passivation interval, and self-corrosion potential decreased, while the dimensional passivation current density increased, and the pitting sensitivity was enhanced. With a further increase in temperature, the capacitive arc radius of 2205 DSS decreased, the film resistance and charge transfer resistance gradually decreased, the carrier density of the donor and acceptor in the product film layer with n + p bipolar characteristics also increased and the inner layer of the film with Cr oxide content decreased, while the outer layer with Fe oxide content increased, the dissolution of the film layer increased, the stability decreased, and the number and pore size of pits increased.

Observations of CO2 Corrosion-Induced Carbonate Scale Formation and Inhibition on Mild Steel

Summary Aqueous CO2-containing environment is ubiquitous in oil and gas production. Carbonate scales (e.g., calcite) tend to form in such an environment. Meanwhile, the CO2 corrosion of mild steel infrastructure may result in corrosion-induced scales including siderite (FeCO3). Previously, siderite was generally treated as a corrosion problem rather than a scale problem. However, the relationship between the corrosion-induced scale and other metal carbonate scales on the steel surface is unclear. For example, how does siderite influence calcite deposition on the mild steel? In this study, the mild steel corrosion and mineral carbonate scaling behaviors were investigated simultaneously in the presence of various cations such as Ca2+ and Mg2+. We observed a two-layer scale structure on the mild steel surface under simulated oilfield conditions. The inner layer is an iron-containing carbonate scale such as ankerite or siderite, while the outer layer is calcite. In addition, calcite deposition at a very low saturation index was observed when the inner layer was present. Furthermore, a common scale inhibitor [diethylenetriaminepentakis(methylenephosphonic acid) or DTPMP] can effectively mitigate calcite, siderite, and ankerite formation on the steel surface, but meanwhile, aggravate the steel corrosion because of the absence of protective scale layers.

Density functional theory and molecular dynamics simulation of the corrosive particle diffusion in pyrimidine and its derivatives films

The search and discovery of corrosion inhibitors to mitigate sweet corrosion in the oil and gas industry has been carried out mainly using tedious and costly experimental approaches. In this study, theoretical approach using density functional theory (DFT) and molecular dynamics (MD) simulation were utilized to investigate the adsorption and diffusion properties of pyrimidine and six (6) of its derivatives on carbon steel corrosion in simulated CO2-containing environment. The DFT calculations revealed that the electrons can easily flow from the HOMO orbitals of all the pyrimidine molecules to the empty substrate orbitals until reaching the equilibrium state as the values of EHOMO (-7.63 to −5.55 eV) are much higher than the Fermi level energy of Fe (-13.16 eV). Besides, the binding energy of molecules on the Fe (110) surface obtained using MD simulation was found to be in the range of 60.67 to 99.28 kcal/mol, indicating the pyrimidine molecules can strongly interact with the iron atoms of the metal surface. In the sweet medium, the diffusion coefficient (D) of HCO3– was in the range of 0.81 to 1.41 m2 s−1, which is about three times less than the diffusion coefficient of HCO3– in water. Self-diffusion coefficient (D'), and fractional free volume (FFV) were used to further investigate the diffusion mechanism of the pyrimidine molecules in CO2 corrosive medium. Pyrimidine containing carboxylic acid and thioamide groups gave the best result as CO2 corrosion inhibitor theoretically. The DFT and MD results provided useful insights and a theoretical basis for the screening and design of new sweet corrosion inhibitors for carbon steel.

Effect of engineered lattice contraction and expansion on the performance and CO2 tolerance of Ba0.5Sr0.5Co0.7Fe0.3O3-δ functional material for intermediate temperature solid oxide fuel cells

Barium Strontium Cobalt Iron Oxide (BSCF) is a famous cathode material for solid oxide fuel cells (SOFCs) due to its excellent catalytic activity for oxygen reduction reaction (ORR) at intermediate and low operating temperatures. Its poor stability, however, in a CO2-containing environment limits its practical application. In this study, we systematically investigate the effects of instigating lattice contraction and expansion on the performance and CO2 tolerance of Ba0.5Sr0.5Co0.7Fe0.3O3-δ (BSCF) air electrode functional material. We strategically substituted 5 mol.% Fe–B-site cations of BSCF with transition metals (TMs), i.e., Zn and Cu, to achieve lattice expansion and contraction, respectively. The Ba0.5Sr0.5Co0.7Fe0.25Cu0.05O3-δ (BSCFC5) cathode, where lattice contraction occurred, exhibits the best performance with an area-specific resistance (ASR) of 0.0247 Ω cm2 and a high peak power density (PPD) of 1715 mW cm−2 at 650 °C for the symmetrical and single cells, respectively. The functional material also exhibits enhanced tolerance to CO2 compared to BSCF by surviving several rounds of 10% CO2 injection and ejection for an overall nonstop testing period of 100 h. The improved ORR, stability, and CO2 tolerance instigated by lattice contraction in BSCF provides an insight into the adoption of this approach in achieving optimal desirable properties in SOFC cathode functional materials.

Comparison of the synergistic inhibition mechanism of two eco-friendly amino acids combined corrosion inhibitors for carbon steel pipelines in oil and gas production

The combination of corrosion inhibitors is a significant method to enhance the inhibitive effects of inhibitors owing to their synergism. In this work, the inhibition synergism of two eco-friendly amino acids (L-histidine, L-cysteine) and thiourea on the corrosion of N80 carbon steel in CO2-containing environment was studied by electrochemical tests and surface analysis. The results indicate that the combination of L-histidine/L-cysteine and thiourea could synergistically boost the inhibition performance of L-histidine/L-cysteine and thiourea, i.e., present a remarkable inhibition synergism. Moreover, the synergism mechanism is in-depth revealed by theoretical calculations. The stronger interaction between L-histidine and thiourea accounts for the better synergistic inhibition effect.

Corrosion behavior of 35CrMo steel in a CO2/O2 coexistent simulating environment of fire-drive tail gas

Fire-driven technology has triggered significant interest as an effective technology to improve oil recovery. However, corrosion can easily occur since fire-drive tail gas usually contains corrosive gases, such as CO2 and O2. In this work, the corrosion behavior of several 35CrMo steel samples in a fire-drive tail gas environment was studied using weightlessness measurements, surface characterization techniques, and high temperature-pressure electrochemical tests. The research results show that the average corrosion rate of 35CrMo steel in a CO2–O2 coexisting environment is much higher than the average corrosion rate in a CO2-containing environment or O2-containing environment. The localized corrosion rate of 35CrMo steel in an O2-containing environment is higher than the localized corrosion rate in both the case of a CO2-containing environment or a CO2–O2 one. The pitting factor shows that 35CrMo steel exhibits a localized corrosion in an O2-containing environment. The surface characterization results demonstrate that, in a typical fire-drive tail gas environment, the corrosion products are composed of Fe2O3, FeOOH, and Fe3O4. The high temperature-pressure electrochemistry test data shows that in a CO2–O2-oexisting environment, the membrane resistance decreases upon an increase in the O2 content.

Revealing the temperature effects on the corrosion behaviour of 2205 duplex stainless steel from passivation to activation in a CO2-containing geothermal environment

The temperatures and pressures influencing the formation mechanism of the passive film and corrosion products, as well as passivation performance of 2205 duplex stainless steel (DSS), were systematically studied via immersion tests, electrochemical measurements, and various advanced surface techniques. The results indicate that the passive film at 150 °C was an amorphous structure, while the corrosion products were comprised of nano-polycrystalline FeCr2O4, CrOOH, and NiFe2O4 at 300 °C. A Ni-rich layer was observed at the inner interface in both temperatures. A thermodynamic assessment was to validate the experimental results and reveal fundamental corrosion mechanisms of 2205 DSS exposed to the geothermal environments.

Effect of Turbulent Flow on Corrosion Behavior of 6.5Cr Steel in CO2-Containing Environment

Effect of Turbulent Flow on Corrosion Behavior of 6.5Cr Steel in CO2-Containing Environment

In-depth insight into the inhibition mechanism of pyrimidine derivatives on the corrosion of carbon steel in CO2-containing environment based on experiments and theoretical calculations

In this work, with 2-mercaptopyrimidine (MP) as the precursor, a pyrimidine derivative, 2-benzylthiopyrimidine (BTP), is developed as inhibitor to inhibit the corrosion of carbon steel in CO2-containing environment. Electrochemical measurements indicate that MP and BTP present high inhibition performance, especially for BTP with an inhibition efficiency of 99.82 %. Theoretical calculations show that the protonation of MP and BTP hardly occurs. The benzyl substituent in BTP enhances its adsorption ability by preventing tautomeric transformation and forming hydrophobic structure. Both MP and BTP molecules can adsorb on Fe surface in a nearly vertical orientation through the bonding of N and S atoms.

On the early stages of localised atmospheric corrosion of magnesium\u2013aluminium alloys

The surface film on pure magnesium and two aluminium-containing magnesium alloys was characterised after 96 h at 95% RH and 22 °C. The concentration of CO2 was carefully controlled to be either 0 or 400 ppm. The exposed samples were investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron microscopy. The results showed that when the alloys were exposed to the CO2-containing environment, aluminium cations (Al3+) was incorporated into a layered surface film comprising a partially “hydrated” MgO layer followed by Mg(OH)2, and magnesium hydroxy carbonates. The results indicated that aluminium-containing magnesium alloys exhibited considerably less localised corrosion in humid air than pure magnesium. Localised corrosion in the materials under investigation was attributed to film thinning by a dissolution/precipitation mechanism.

Cerium and Gadolinium co-doped perovskite oxide for a protonic ceramic fuel cell cathode

Proton-conducting ceramic fuel cells (PCFCs) show unique advantages over oxygen-ionic-conducting counterparts at intermediate and low temperatures, which have attracted significant attention worldwide in recent years. A critical issue for world-spread applications is inadequate performance due to the lack of appropriate cathodes for PCFCs. Here, cubic perovskite BaCo0.4Fe0.5-xCe0.1RexO3-δ (ReY, Gd x = 0, 0.1) materials are successfully synthesized and evaluated as the cathode in the PCFCs based on BaCe0.7Zr0.1Y0.1Yb0.1O3-δ as an electrolyte material. The Y- or Gd-doped perovskite BaCo0.4Fe0.4Ce0.1Y0.1O3-δ (BCFCeY), BaCo0.4Fe0.4Ce0.1Gd0.1O3-δ (BCFCeG) exhibit larger lattice parameters, and higher electrocatalytic activity comparing to their parent oxide BaCo0.4Fe0.5Ce0.1O3-δ (BCFCe). Among them, BCFCeG shows the best performance. The single cell with BCFCeG as the cathode material exhibits an interfacial polarization resistance as low as 0.12 Ω cm2 and delivers a promising peak power density of 504 mW cm−2 at 600 °C, while the BCFCe-based cell achieves only 437 mW cm−2 at 600 °C. The X-ray diffraction (XRD) results show good chemical compatibility for BCFCeG below 1050 °C. Moreover, it shows favorable stability in CO2-containing environment. This work confirms that BCFCeG could be a promising cathode for PCFCs.

The Effect of Flowing Velocity and Impact Angle on the Fluid-Accelerated Corrosion of X65 Pipeline Steel in a Wet Gas Environment Containing CO2

This study investigated the effect of flowing velocity and impact angle on the fluid-accelerated corrosion (FAC) of X65 pipeline steel in a wet CO2-containing environment by corrosion morphology analysis, electrochemical measurement, and hydromechanical numerical analysis. It has been found that the corrosion behavior was controlled by the ion diffusion rate and shear stress due to the flowing gas. With an increase in the flowing velocity, the pitting corrosion initially decreased and then increased when the flowing velocity exceeded 14 m/s; this increase is caused by the augmentation of shear stress. When the impact angle decreased, the position of serious corrosion gradually moved outwards.

BaCo0.4Fe0.4Zr0.2O3-δ: Evaluation as a cathode for ceria-based electrolyte IT-SOFCs

Zr-doped perovskite-type material BaCo0.4Fe0.4Zr0.2O3-δ (BCFZ) is prepared and systematically studied via X-ray diffraction (XRD) analysis, dilatometry and temperature-programmed desorption (TPD) of oxygen. The electrochemical performance of the BCFZ is characterized using electrochemical impedance spectroscopy (EIS) with symmetric cell configurations. BCFZ not only shows high oxygen reduction reaction (ORR) electro catalytic activity but also exhibits excellent compatibility with ceria-based (Ce0.8Sm0.2O1.9, SDC) electrolyte. They have a similar thermal expansion coefficient and no chemical reaction. With a BCFZ cathode, the SDC-based SOFC (Ni-SDC|SDC|BCFZ) shows high power densities (879 and 669 mW cm−2 at 650 and 600 °C, respectively). Moreover, it shows favorable stability in CO2-containing environment under SOFCs operating conditions.