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The purpose of this paper is to study the corrosion rate for X52, X60, X65, X70 and X80 steel immersed in Mexican oilfield produced water. For the electrochemical characterization of the five steels rotating disk electrodes, 20°C, 30°C and 45°C of experimental temperature and 0, 500, 1,000 and 2,000 rpm of rotation speed were taken into account. The temperature dependence was analyzed using Arrhenius law. Thus, Rct values obtained from EIS data in comparison with the corrosion rate obtained from polarization curves data were taken into account. Hydrodynamic effects were analyzed by Rct and corrosion rate data.

Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to assess the electrochemical behavior for five pipe steels steel immersed in a natural solution.

The resistance and corrosion rate taken from electrochemical tests decreased as temperature and hydrodynamic condition also decreased. In addition, the Arrhenius parameter revealed that the natural solution increased the corrosion rate as the activation energy decreased. Typical branches related to reduction-oxidation reaction (dissolution-activation process or corrosion products dissolution) on steel surface were discussed. Optical images analysis shows that corrosion products for X65 steel exposed to oilfield produced water can be attributed to more susceptibility to corrosion damage for this steel grade (Quej-Ake et al., 2018), which is increased with the temperature and rotation speed of the working electrode.

Corrosion process of the five steels exposed to oilfield produced water could be perceptive when Arrhenius analysis is taken into account. This is because oilfield produced water is the most aggressive condition (brine reservoir and sour water) for internal pipelines walls and storage tanks (brine tanks). Thus, stagnant condition was considered as a more extreme corrosive condition because produced water is stored in atmospheric stationary tanks as well as it is transported under laminar condition in zones where oilfield produced water is maintaining in the bottom of the pipe during the production, transporting and storing of the crude oil. In addition, a brief operational process for Reynolds number and the flowrate of the stock tank barrel per day (Q in STBD) using field and Reynolds number data is discussed.

The purpose of this paper is to study the corrosion process by examining the deterioration of X80 steel exposed to a real petroleum sample containing condensed hydrocarbon plus oilfield-produced water, which were subjected to stimulated emulsions in flowing media at 50°C.

The impedance and polarization spectra were used to assess the aggressiveness of the petroleum sample and tried to find a washing process using condensed hydrocarbon with deionized water. Mössbauer technique was used to identify the phases in precipitated ions obtained during an oven-drying procedure of the oilfield produced water.

The emulsion, chloride, sulphur compounds, heavy metals and the use of a double hydrodynamic system were the most important factors affecting the corrosion of X80 steel. The corrosion rate of this steel increased when oilfield-produced water was stimulated by a double hydrodynamic system (4.56 mm/year). It was determined to be 7.66 mm/year and 4.01 mm/year when steel was exposed to a stimulated emulsion using the petroleum sample and condensed hydrocarbon with deionized water at 24 h, respectively, suggesting that a significant process of hydrocarbon washing could occur and a more corrosive solution was highlighted. Mössbauer results showed that the ions precipitates included the following phases at Wt.%: magnetite (20.0), greigeite (22.8), siderite (3.2), pyrite (2.9), marcasite (26.7) and mackinawite (24.4).

A stimulated hydrocarbon/water emulsions with a more homogeneous solution containing high concentrations of saline compounds and heavy metals were used to simulate the susceptibility to corrosion on the internal pipeline steels exposed to any type of immiscible liquids such as condensed hydrocarbon, or crude oil, containing water. A practical application of the presented research could provide a novel framework for understanding the internal corrosion in pipelines from the simulation of washed hydrocarbons after the stimulated emulsions that can be found in the field. Because more susceptibility to corrosion for pipeline steels would be expected at the end of the transportation of the fluid. It is possible to investigate the possible corrosion mechanisms by using a dried oilfield-produced water sample interacting with the pipeline steels.

The purpose of this study is to investigate the performance of the fabricated liquid–liquid hydrocyclone (LLHC) with dimensions similar to those of one of the Malaysian oilfields with the presence of an anionic surfactant, S672. The effect of salinity and initial oil concentration were also investigated following the actual range concentration.

The current control system’s pressure drop ratio (PDR) does not necessarily lead to an efficient LLHC. Therefore, rather than using the PDR, the efficiency of the LLHC was analyzed by comparing the concentration of oil in the effluents with the concentration of oil at the feed of the LLHC. An LLHC test rig was developed at Centre of Enhanced Oil Recovery, Universiti Teknologi PETRONAS. Emulsions were prepared by mixing the brines, S672 and oil by using Ultra Turrax ultrasonic mixer. The emulsion was pumped into the LLHC at different feed flowrate and split ratio. The brines concentration, initial oil concentration and S672 concentration were also varied in this study. Samples were taken at the underflow of the LLHC and the oil in water concentration analysis was done for the samples using TD-500D equipment.

It was found that the efficiency of oil removal decreased with an increase in S672 concentration but increased with the increase in salinity and initial oil concentration.

The optimum feed flowrate for the LLHC of 45 mm diameter and length of 1,125 mm with the presence of S672 surfactant was found to be 40 L/min with a split ratio of 14%. This study can be used as a guidance for future optimization of the LLHC in the presence of the surfactant.

The purpose of this research is to study different extra-heavy crude oil-in-water emulsions that can be found in practice for corrosion process of X52 steel adding 60 mg.L-1 of non-ionic surfactant and a corrosion inhibitor (CI). Electrochemical impedance spectroscopy and Tafel plots are carried out. Thus, Bode-modulus and Bode-phase angle plots are discussed. Adsorption isotherms obtained from corrosion rate (CR) values are taken into account.

Two-electrode arrangement is used to characterize the pseudo-capacitance values for X52 steel exposed to water and crude oil phases, mainly. Electrochemical evaluations for X52 steel exposed to extra-heavy crude oil-in-water emulsions are recorded in a conventional three-electrode cell to study the corrosion process as was documented in detail by Quej-Ake et al. (2015). Therefore, all electrodes are placed as close as possible to eliminate the iR-drop.

Pseudo-capacitance analysis shows that X52 steel immersed in oilfield produced water was more susceptible to corrosion than that immersed in ocean water solution and extra-heavy crude oil phase. After being analyzed, the X52 steel surface coverage and adsorption process for surfactant and CI could be concluded that surfactant could protect the metal surface. In a coalescence extra-heavy crude oil-in-water emulsion, the water medium generated a new solution that was more corrosive than the original water phase. Wash crude oil process was provoked in emulsion systems to sweep up the salts, mainly. Thus, corrosive species that can be recovered inside extra-heavy crude oil may appear, and in turn a new more corrosive solution could be obtained. Taking into account the straight line obtained in Bode-modulus plot for X52 exposed to extra-heavy crude oil, it is possible to point out that the negative value of the slope or R² can be related to a coefficient (Jorcin et al., 2006). It is important to mention that electrochemical responses for X52 steel exposed to extra-heavy crude oil-in-water under coalescence emulsions revealed that corrosion and diffusion processes exist. Therefore, a possible good inhibitor is surfactant in emulsion systems.

CR and anodic and cathodic slopes suggest that the surfactant acted as mixed CI. Of these, susceptible anodic (MnS and perlite or cementite) and cathodic (ferrite) sites on steel surface could be affected, due to which physicochemical adsorption could happen by using electrochemical parameters analysis. Thus, no stable emulsions should be taken into account for extra-heavy crude oil transportation, because corrosion problems in atmospheric distillation process of the crude oil due to stable emulsion cannot be easily separated. In this manner, coalescent emulsions are more adequate for transporting extra-heavy crude oil because low energy to separate the water media is required.

Oil-water two-phase flow is the most prevalent medium in oil field gathering pipelines, and the corrosion of pipelines is often highly localized. Therefore, the purpose of this paper is to investigate the corrosion behavior of 20# pipeline steel in the oil-water stratified liquids, vary the water content of the upper emulsion and study the difference of the corrosion process.

Combine the wire beam electrodes (WBE) technique and the corrosion weight loss method to investigate the corrosion behavior of 20# steel in produced water simulation fluid and oil-water stratified liquids, and a corrosion mechanism model was established for analysis and explanation.

The results of mass loss experiments showed that the average corrosion rate increased with the increase in the water content of the upper emulsion. The corrosion current distribution maps indicated that the most serious corrosion occurred in the produced water simulation liquid, and the corrosion process showed the law of waterline corrosion. In addition, it was also found that the corrosion of the WBE in the stratified liquids had obvious non-uniformities. The electrode wires at the oil-water interface suffered from severe corrosion, caused by the dissolution of crude oil acids in water and the uneven distribution of oxygen in the corrosive medium.

The WBE technique provides a deep insight into the corrosion phenomena at the oil-water interface, which is helpful for characterization of the non-uniformity of corrosion parameters and evaluating the risks of multiphase corrosive media.

The salinity of the oilfield produced water has a significant effect on steel corrosion. The purpose of this paper is to study the influence of salinity on corrosion behavior of X60 steel and it also provides basic for material selection of gas wells with high salinity.

The weight loss experiment was carried out on steel with high temperature and high pressure autoclave. The surface morphology and composition of corrosion scales were studied by means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry.

The results show that as salinity increases, the corrosion rate of X60 steel will gradually experience a rapid decline stage and then a slow decline stage. X60 steel is mainly exhibiting uniform corrosion in the first rapid decline stage and pitting corrosion in the second slow decline stage. The increase in salinity reduces gas solubility, which, in turn, changes the morphology and density of the corrosion scales of X60 steel. At low salinity, loose iron oxides generated on the surface of the steel, which poorly protects the substrate. At high salinity, surface of the steel gradually forms protective films. Chloride ions in the saline solution mainly affect the structure of the corrosion scales and initiate pitting corrosion. The increased chloride ions lead to more pitting pits on the surface of steel. The recrystallization of FeCO₃ in pitting pits causes the corrosion scales to bulge.

The investigation determined the critical concentration of pitting corrosion and uniform corrosion of X60 steel, and the new corrosion mechanism model was presented.

The purpose of this paper is to research whether microstructure varieties of zones at welded joints pose a tremendous effect on its corrosion in SC-CO₂.

The interrelation between the corrosion and microstructure of base metal (BM), fine grain heat affected zone (FHAZ), coarse grain heat affected zone and weld metal (WM) in welded of X80 steel in water saturated supercritical CO₂ was studied by using optical microscope, weight loss test, electrochemical measurements and surface analytical techniques.

The all subzones of X80 weld joints were attacked by SC-CO₂ corrosion and showed flower-like corrosion scale spots consisted of granular FeCO₃. The most severe corrosion appeared at WM due to lower proportion of ferrite to pearlite, but the slightest corrosion displayed at BM. GHAZ with larger grains and more polygonal ferrite exhibited more severe corrosion than that at BM. Due to its smaller grain, FHAZ displayed comparatively more severe corrosion to that at BM.

There exists close interrelation between the corrosion and microstructure of the welded carbon steel in water saturated supercritical CO₂.

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO₂/oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behavior of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of flow velocity, CO₂ partial pressure and water cut on the CO₂ corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature of 60°C and CO₂ partial pressure of 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

The results showed that corrosion rates of X65 steel both increased at first and then decreased with the increase of flow velocity and CO₂ partial pressure, and there were critical velocity and critical pressure in the simulated corrosive environment, below the critical value, the corrosion products formed on the steel surface were loose, porous and unstable, higher than the critical value, the corrosion product ?lms were dense, strong adhesion, and had a certain protective effect. Meanwhile, when the flow velocity exceeded the critical value, oil film could be adsorbed on the steel surface more evenly, corrosion reaction active points were reduced and the steel matrix was protected from being corroded and crude oil played a role of inhibitor, thus it influenced the corrosion rate. Above the critical CO₂ partial pressure, the solubility of CO₂ in crude oil increased, the viscosity of crude oil decreased and its fluidity became better, so that the probability of oil film adsorption increased, these factors led to the corrosion inhibition of X65 steel reinforced. The corrosion characteristics of gathering pipeline steel in the corrosive environment containing CO₂ would change due to the presence of crude oil.

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

The purpose of this work is to design the wire beam electrode (WBE) of P110 steel and study its corrosion behavior and mechanism under high temperature and pressure.

Packaging materials of the new type P110 steel WBE and high pressure stable WBE structure were designed. A metallurgical microscope (XJP-3C) and scanning electron microscopy (EV0 MA15 Zeiss) with an energy dispersive spectrometer were used to analyze the microstructure and composition of the P110 steel. The electrochemical workstation (CS310, CorrTest Instrument Co., Ltd) with a WBE potential and current scanner was used to analyze the corrosion mechanism of P110 steel.

According to the analysis of Nyquist plots at different temperatures, the corrosion resistance of P110 steel decreases with the increase of temperature under atmospheric pressure. In addition, R_p of P110 steel under high pressure is maintained in the range of 200 ∼ 375 Ωcm², while that under atmospheric pressure is maintained in the range of 20 ∼ 160 Ωcm², indicating that the corrosion products on P110 steel under high pressure is denser, which improves the corrosion resistance of P110 steel to a certain extent.

The WBE applied in high temperature and pressure environment is in blank. This work designed and prepared a WBE of P110 steel for high temperature and pressure environment, and the corrosion mechanism of P110 steel was revealed by using the designed WBE.

The purpose of this study is to provide ideas and theoretical guidance for green, environmentally friendly and efficient “bacteriostasis with bacteria” technology.

In this paper, a beneficial strain of bacteria was extracted and purified from marine mud. Weight-loss test, morphological observation and electrochemical test were used to systematically study the effect of sulfate-reducing bacteria (SRB)-induced corrosion inhibition on X65 steel in simulated offshore oil field production water.

The results showed that a beneficial strain was selected and identified as Vibrio alginolyticus. Under the condition of co-culture of SRB, the average corrosion rate of X65 steel was significantly reduced. In the mixed bacterial system, the surface of X65 steel samples was relatively flat, and the structure of biofilm and corrosion product film was dense. The number of corrosion pits, the average diameter and depth of corrosion pits were significantly reduced. The localized corrosion of X65 steel was significantly inhibited.

The complex and changing marine environment makes the corrosion problem of marine steel increasingly severe, and the microbiologically influenced corrosion (MIC) caused by SRB is particularly serious. The research and development of environmentally friendly corrosion protection technology is a long-term and difficult problem. The use of beneficial microorganisms to control MIC is a green and efficient anticorrosion measure. Compared with terrestrial microorganisms, marine microorganisms can adapt to complex environments, and their metabolites exhibit special biological activities. The use of marine beneficial bacteria can inhibit SRB activity to achieve the corrosion inhibition effect.