Injection Of Corrosion Inhibitors Research Articles

Key Challenges for Internal Corrosion Modelling of Wet Gas Pipelines

Abstract The presence of CO2 and H2S in wet gas pipelines often creates the potential for high internal corrosion rates, which is typically mitigated by the injection of corrosion inhibitors. In practice, however, it is difficult to ensure that the inhibitor is always injected at the right level, while actual conditions in the pipeline may sometimes vary from those for which the inhibitor was qualified. Consequently, pipelines are also likely to be inspected from time to time using In-Line-Inspection tools. Various empirical and mechanistic models are used to estimate corrosion rates in such pipelines, both during the design phase to establish corrosion allowances and inhibitor availability requirements, and then during operation to help interpret inspection results and guide further operational decisions. These models can differ considerably in how they incorporate the effects of surface scaling, while the effects of inhibitors are generally not included in any mechanistic sense. This paper provides an overview of corrosion assessment for wet gas pipelines, with a particular focus on recent developments in modeling scale formation and the influence of inhibitors.

Temperature Dependence of Adsorption and Effectiveness for a Pyrimidinium-Type Corrosion Inhibitor on Mild Steel

In the oil and gas industry, produced water with a high dissolved salt content is a common byproduct of hydrocarbon extraction from conventional and unconventional wells. Other than salts, corrosive gases such as CO2 are abundant in the production stream, which dissolve and acidify the solution, posing a risk of internal pipeline corrosion. To mitigate this issue, injection of corrosion inhibitors has emerged as a cost-effective approach. In various aggressive conditions, heterocyclic molecules that contain nitrogen atoms have proven to be highly effective corrosion inhibitors for many alloys. In this study, tetrahydropyrimidinium (THP-C14) inhibition efficiencies were investigated at temperatures of 25°C, 55°C, and 80°C using electrochemical methods, including linear polarization resistance and potentiodynamic sweeps. Corrosion inhibition data were then correlated with THP-C14 concentration, using the five adsorption isotherms: Langmuir, Temkin, Frumkin, Flory-Huggins, and Dhar-Flory-Huggins models. These isotherms utilize different assumptions to establish the correlation between coverage and inhibitor concentration. The suitability of these five isotherm models for describing the corrosion inhibition behavior of THP-C14 was examined. In addition, the thermodynamic parameters (Kad, ΔadGo) of adsorption for THP-C14 at 25°C, 55°C, and 80°C were calculated and compared using the aforementioned adsorption isotherm models. Finally, a mechanism was proposed for the adsorption behavior of the THP-C14 corrosion inhibitor model compound. Chloride ions were important for inhibitor adsorption.

Corrosion Inhibitor Distribution and Injection Cycle Prediction in a High Water-Cut Oil Well: A Numerical Simulation Study

The wellbore downhole strings corrosion has attracted extensive interest as most of the oilfields in China enter the high water-cut period. Injection of corrosion inhibitors, one of the most effective corrosion protection methods, is employed to mitigate the wellbore corrosion. Nevertheless, its wider application suffers from insufficient knowledge regarding the distribution of corrosion inhibitors inside the tubing, particularly with different inhibitor injection cycles. Thus, in this study, the computational fluid dynamics (CFD) method was first attempted to investigate the hydrodynamics in a tubing and the interactions between the corrosion inhibitor and produced fluid with high water-cut. Key factors including the time, wellbore heights, injection rates, oil phase velocities and corrosion inhibitor viscosities were discussed in detail as regards how they affect the corrosion inhibitor distribution inside the tubing. Feasible formulas were established for predicting the volume fraction of the corrosion inhibitor at different wellbore heights, which showed good agreement with the simulation results. It is noted that the determination of the corrosion inhibitor injection rate depends on both the film quality of the corrosion inhibitor and the stability of the annular flow. Based on the interphase diffusion effect, a new method for determining the intermittent injection cycle of corrosion inhibitor was proposed to maintain the integrity of corrosion inhibitor film at the tubing inner wall.

Current Downhole Corrosion Control Solutions and Trends in the Oil and Gas Industry: A Review.

In the oil and gas industry, the presence of aggressive fluids and gases can cause serious corrosion problems. Multiple solutions have been introduced to the industry to minimize corrosion occurrence probability in recent years. They include cathodic protection, utilization of advanced metallic grades, injection of corrosion inhibitors, replacement of the metal parts with composite solutions, and deposition of protective coatings. This paper will review the advances and developments in the design of corrosion protection solutions. The publication highlights crucial challenges in the oil and gas industry to be solved upon the development of corrosion protection methods. According to the stated challenges, existing protective systems are summarized with emphasis on the features that are essential for oil and gas production. Qualification of corrosion protection performance based on international industrial standards will be depicted in detail for each type of corrosion protection system. Forthcoming challenges for the engineering of next-generation materials for corrosion mitigation are discussed to highlight the trends and forecasts of emerging technology development. We will also discuss the advances in nanomaterial and smart material development, enhanced ecological regulations, and applications of complex multifunctional solutions for corrosion mitigation which have become of great importance in recent decades.

Matrix/rebar rehabilitation through electrochemical injection of Ce(III)/imidazolium-based ILs as a novel anti-corrosion pore-blocking technique for increasing the sustainability of reinforced cementitious materials

This research proposed a novel method in the electrochemical injection of corrosion inhibitors (EICI) using imidazolium-based ionic liquids and Ce(III) as a pH-sensitive pore-blocking compound to reduce rebar corrosion and increase the sustainability of the in-use chloride-contaminated reinforced cementitious materials. The analytical approach was conducted on the simulated concrete pore solution and mortar media for 360 days. Compared to the typical EICI approach, our boosted EICI rehabilitation approach improved long-term performance by almost 90%. The volumetric analysis demonstrated that by precipitating Ce-rich compounds, the Ce(III) injection reduced the number and size of porosities while lowering 15% of the interconnected pores. Data AvailabilityThe raw and processed data required to reproduce these findings cannot be shared at this time since the data also forms part of an ongoing study.

Development and application of a passion fruit seed oil microemulsion as corrosion inhibitor of P110 carbon steel in CO2-saturated brine

One of the most important causes of corrosion in the oil industry is CO2 and the injection of corrosion inhibitors is an economical way to prevent it. Recently, many efforts have been made to develop eco friendly corrosion inhibitors. This work reports the development of ecological microemulsified systems based on passion fruit seed oil applied as corrosion inhibitors for carbon steel pipes P110 in synthetic brine saturated with CO2, at different temperatures and inhibitor concentrations. The inhibition efficiency was investigated by tests of weight loss, linear polarization resistance, electrochemical impedance spectroscopy and polarization curves. The gravimetric measurements showed maximum efficiency of 975 %. The results of the electrochemical tests presented the same trends: increased inhibition efficiency at higher microemulsion concentration and lower efficiency with higher temperature. Based on Electrochemical parameters of polarization tests, the corrosion inhibition efficiency of the microemulsion M8 exceeded 99 % and the presence of the microemulsion promoted a reduction of the anodic and cathodic reactions involved in the corrosion process, characterizing the microemulsion as an adsorption inhibitor. The study of the metal surface morphology by scanning electron microscopy and contact angle measurement confirmed the ability of the microemulsion to form a film to protect the metal against attack by electrolytes.

Efficacy and efficiency of dual electrochemical strategies for remedying rebar corrosion in heterogeneous concrete

Corrosion of rebars continues to be a major concern for the durability of steel reinforced concrete structures. To minimize the risk involved with rebar corrosion in this study two electrochemical remedial strategies, i.e., electrical injection of corrosion inhibitors (EICI) and electrochemical removal of chlorides (ERC), are investigated in this study using an integrated analytical and experimental approach. A mathematical model in the form of a multiphysics, non-linear differential equation was established for evaluating the efficacy and efficiency of a parallel EICI and ERC scheme, aided by three accelerated electrochemical experiments developed for parametric determination and for model validation. Based on the method of three-dimensional microstructure reconstruction, a finite element analysis was applied to solve the mathematical model that couples three key mechanisms of mass transport in the matrix of heterogeneous concrete, including natural diffusion, hydraulic migration and electromigration. The validated mathematical model indicates an optimum current density of 3 A/m2 for implementation. Being able to predict the concentrations of multiple chemical species at arbitrary times and locations in heterogeneous concrete, the developed mathematical model demonstrates to be a powerful tool for evaluating general chemical-deterioration problems and remedial strategies for concrete structures.

Requirement and Calculation of Corrosion Allowance for Piping and Valves in the Oil and Gas Industry

“Acid Gases” refer to two of the undesirable by-products of oil and gas, namely CO2 and H2S$$.$$ The reaction of H2S and other sulphur compounds with water increases the degree of “sour corrosion” by forming sulphuric acid. CO2 corrosion of carbon and alloy steels is designated as “Sweet Corrosion” which is defined as the deterioration of metal components resulting from contact with gas or solutions including both CO2 and water. CO2 corrosion is an important problem in the oil and gas industry due to metal loss and its severe effects in terms of localized corrosion. Accurate prediction and modelling of CO2 corrosion rates for carbon and alloy steel pipes are vital tasks at the basic design phase of oil, gas and petrochemical projects in order to determine whether to consider additional wall thickness for the pipes and valves defined as “Corrosion Allowance (CA)” or to change the pipes’ or valves’ base materials to “Corrosion Resistance Alloys (CRA)”. Other corrosion mitigation approaches such as injecting the corrosion inhibitors and glycol or methanol can reduce the metal loss and CO2 corrosion. This paper proposes a practical model to calculate and select the corrosion allowance for piping and valves in oil and gas industry. Different process parameters such as scaling, fugacity, pH, glycol and corrosion inhibitor injection, water cut, operating pressure and temperature as well as CO2 partial pressure have been applied in the model.

A comparison study of the performance of three electro-migrating corrosion inhibitors in improving the concrete durability and rehabilitating decayed reinforced concrete

Electro-migration (EM) treatment with injection of corrosion inhibitors is regarded as an efficient method to rehabilitate decayed reinforce concrete architectures and structures. In order to explore the advantages of different electrolytes used in this method, three reported nitrogenous electro-migrating inhibitors: guanidine, 1,6-hexamethylenediamine (HMDA) and 3-aminopropyltriethoxysilane (APS) were selected and their effectiveness on reinforced cement mortar durability were compared. APS and HMDA can more efficiently prevent the external aggressive factors (water, chloride and carbonation) rather than guanidine, while guanidine shows advantage in recovering the mortar alkalinity after EM treatment. To select the appropriate electro-migrating corrosion inhibitors, not only the inhibitive effect, but also their effectiveness on removing chloride and re-alkalization and enhancing the resistance to external aggressive factors should be taken into account.

Electrochemical process to improve the durability of concrete structures

Chloride induced corrosion of steel in concrete is a major threat to the construction industry leading to the premature failure of concrete structures. Electrochemical injection of corrosion inhibitor (EICI) into concrete is a promising technique for existing concrete structures, which can serve as a rehabilitative measure to retard or reduce rebar corrosion. An attempt has been made to evaluate the effectiveness of a hybrid inhibitor formulation injected into chloride contaminated concrete. The optimised current density of 0.5A/m2 was found to be a minimum requirement with maximum efficiency. During EICI, the amount of free chloride removed from cover concrete was also tested. The mechanism of inhibitive action was established through FTIR, SEM, EDAX and MIP studies.

The role of surface and subsurface integration in the development of a high-pressure and low-production gas field

Against a background of gradual changes in the global energy consumption structure, clean natural gas still plays an indispensable role in satisfying energy needs. Xushen gas field in Songliao Basin has held the balance in gas-producing areas in China since its exploitation in 2004, especially by “using a gas to supply oil output” strategy in Daqing oilfield. However, the difficulties and beneficial results of development in the field are challenged by the very cold climate, poor reservoir property and high amounts of CO2 in natural gas. An investigation of the heat-tracing measures for preventing the formation of natural gas hydrates and selection of stainless steel pipes and a high-pressure equipment to restrain CO2 corrosion in Xushen gas field operation was carried out recently. In this paper, the hydraulic and thermal characteristics of gas gathering pipelines is studied, including a discussion on the effect of high pressure and low production on the formation of natural gas hydrates during transportation and the determination of technical limits for inhibiting the formation of hydrates under different conditions. Subsequently, the gas production process, including purification and defoaming parameters in a high-pressure and low-production field, is optimized. The results indicate that the surface engineering construction would take up more than 30 % of the total investment in gas field development, especially in high-pressure and low-production areas, and that it would be necessary to design a simplified production process for multi-well gathering and single-well rotation. Meanwhile, the role of surface and subsurface integration would be better played by improving the key production units such as wellbore throttling, gathering pipe heat tracing, corrosion inhibitor injection and gas purification disposal. This study will contribute to obtaining the maximum benefits in green gas field development.

Effect of Electrical Injection of Corrosion Inhibitor on the Corrosion of Steel Rebar in Chloride-Contaminated Repair Mortar

The electrical rehabilitation treatments of repair mortar were performed with tetrabutylammonium bromide salt (TBAB) at an electrical current density of 5 A/m2, using two electrolytes (0.1 M NaOH and 0.1 M Na3BO3solutions), and for two time periods (1 and 4 weeks), respectively. The average organic cation-based inhibitor’s concentration in cement mortars before and after this treatment was quantified using the UV-Vis spectroscopy. The experimental results reveal that the EICI treatment with 0.1 M Na3BO3was more effective in injecting the inhibitor and in improving the chloride penetration resistance and compressive strength of the mortar, relative to using 0.1 M NaOH as electrolyte. In this case, after the 4-week EICI treatment, [TBA+] contents were 2.3 % and 2.4% by mass of cement mortar for uncontaminated and salt-contaminated mortars, respectively. After the 4-week EICI treatment, the apparent diffusion coefficients of chloride anion in cement mortar were decreased by 40% from 1.52 × 10−10 m2/s. The EICI treatment was able to halt the chloride-induced corrosion of the steel rebar by promoting its passivation. The 2-week EICI treatment using sodium hydroxide and sodium borate solutions decreased the corrosion current density of the rebar by 77.8% and 78.5%, respectively, approximately two months after the treatment.

Verification of Corrosion Inhibitor Injection Flow Rates for a Subsea Oil/Gas Field

This paper presents the basic principle and practice involved in verifying that the total amount of corrosion inhibitor injected from topsides is in balance with the total amount injected from the each of the four manifold. Chemical injection metering valves (CIMV) into the respective flowlines for this field. Inadequate inhibition will significantly increase the risk of corrosion of the flowlines. Below target CI injection rates may be experienced during simultaneous injection into multiple subsea manifolds from the CIMV due to: errors in estimating the required injection flow rates and/or setting the CIMV’s; malfunction of the CIMV (e.g., instrumentation or fatigue failure); corrosion inhibitor delivery to the subsea manifolds being highly sensitive against pressure and viscosity fluctuations and thereby resulting in significant flow deviations; variable volumes of production fluids and percentage water cut. Below target injection flow rates will result in increased susceptibility to flowline corrosion while above target injection rates will result in cost penalties. The verification requirements for this subsea field are based on the mass balance principle which requires that the mass of CI injected topsides (input) should be equal to the total mass of CI injected simultaneously into all the subsea manifolds (input). It is recommended that the verification scheme should be implemented initially every 3 months during production by recording the observed CI flow rates (topsides and subsea) in the prepared data sheets, evaluating recorded data and performing corrective actions as required. Based on assessment of historic conformance of actual injection rates with target, further verification may be required during downtime, in order to determine the mass balance status and hence the CIMV performance over the full range of settings (25, 50, 75, and 100%).

Application of electrochemical organic corrosion inhibitor injection to a carbonated reinforced concrete railway viaduct

As a possible means of alleviating carbonation-induced reinforcement corrosion in aging reinforced structures, electrochemical injection of corrosion inhibitors has been proposed. This method involves application of aqueous solutions of organic base corrosion inhibitors onto the concrete surface with controlled current densities passed between anodes placed within the inhibitor solutions and the embedded steel bars acting as cathodes. This present contribution describes a site trial of electrochemical inhibitor injection applied to a 40-year-old carbonated high-speed railway viaduct in Tokyo. The efficiency of inhibitor penetration to the embedded reinforcement and the electrochemical effects brought about by the proposed method are discussed.

Inhibitive Assesment of Stearamide as a Corrosion Inhibitor for Mild Steel in HCl Solution

In this study effect of Stearamide as a corrosion inhibitor for mild steel in hydrochloric acid media was investigated employing various electrochemical techniques include potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and liner polarization resistance (LPR). In view of the fact that Stearamide is an insoluble compound in water, its inhibitive effect was examined by dissolving 10000ppm of it into an organic solvent followed by immersing of steel surface into the solution for 7, 15, 30 and 60 minutes. As a result of the immersion of steel into the solution, the Stearamide was allowed to be adsorbed on the surface and its corrosion inhibition was investigated by moving the sample into a 0.1M HCl solution and employing several electrochemical techniques. Such a method of inhibitor adsorption is regularly used during corrosion inhibitor injection into the gas well tubing. The results of investigation show that Stearamide acts as adsorptive inhibitor, reduces anodic dissolution and also retards the hydrogen evolution reaction via blocking the active reaction sites on the metal surface. Additionally, it was illustrated that Isopropyl alcohol is a more beneficial solvent for Stearamide as compared to demethyl sulfoxide (DMSO). Isopropyl alcohol acts as inhibitor itself and its mixture with Stearamide has synergistic effect on corrosion inhibition. The optimal condition of immersing steel into the solution was 15min immersion of mild steel in both solutions, and the inhibition efficiency was approximately 90% when Isopropyl alcohol was used as the solvent. EIS investigation demonstrates that the thickness of protective layer formed on metal surface by Isopropyl alcohol solution is almost 5 times higher than that formed by DMSO.

Sour Top-of-the-Line Corrosion in the Presence of Acetic Acid

Abstract Under stratified flow and dewing conditions, internal corrosion can occur at the top of horizontal pipelines where continuous injection of corrosion inhibitors does not have a mitigating effect. This research work presents an experimental study of the influence of the presence of hydrogen sulfide (H2S; up to 0.13 bars) and acetic acid (HAc; up to 1,000 ppm) on carbon dioxide (CO2) top-of-the-line corrosion. The study was performed in a 10 cm (4 in) internal diameter flow loop with system conditions constant at 70°C, 2 bars partial pressure CO2, 3 bars total pressure, 5 m/s gas velocity, and a water condensation rate of 0.25 mL/m2/s. A comprehensive analysis on the effect of these parameters (partial pressure of H2S and concentration of acetic acid) on the type of corrosion product film formed at the top of the line is performed.

Electrochemical Chloride Extraction and Electrochemical Injection of Corrosion Inhibitor in Concrete: State of the Knowledge

Article Electrochemical Chloride Extraction and Electrochemical Injection of Corrosion Inhibitor in Concrete: State of the Knowledge was published on April 1, 2009 in the journal Corrosion Reviews (volume 27, issue 1-2).

Assessment of Electrical Injection of Corrosion Inhibitor for Corrosion Protection of Reinforced Concrete

Chloride ingress is the major cause of rebar corrosion that deteriorates reinforced concrete structures in chloride-laden environments. A recently emerged electrochemical technique—the electrical injection of corrosion inhibitor (EICI)—shows its potential in protecting a rebar from chloride attack by driving corrosion inhibitors to the rebar surface under an externally applied electric field. Potential applicability of EICI as a routine electrochemical treatment for corrosion protection is assessed. A comprehensive evaluation of currently available organic cation-based inhibitors was conducted on the basis of the measured corrosion inhibition performance and diffusion coefficient of each inhibitor. With the use of a two-dimensional finite element model, the concentration evolution of the selected inhibitors and chloride were predicted on the rebar surface and in concrete, and the applicability of EICI was examined thereafter. Important aspects of EICI were studied including mainly inhibitor type, magnitude of applied current density, and treatment time. Recommendations about EICI practice were made accordingly.