Film-forming Corrosion Inhibitors Research Articles

Synergistic Gas Hydrate and Corrosion Inhibition Using Maleic Anhydride: N-Isopropylmethacrylamide Copolymer and Small Thiols.

Kinetic gas hydrate inhibitors (KHIs) are often used in combination with film-forming corrosion inhibitors (CIs) in oilfield production flow lines. However, CIs can be antagonistic to KHI performance. In this study, maleic anhydride-co-N-isopropylmethacrylamide copolymer (MA:NIPMAM) and its derivatives were successfully synthesized and tested for gas hydrate and corrosion inhibition. KHI slow constant cooling (1 °C/h) screening tests in high-pressure rocking cells with synthetic natural gas and CO2 corrosion bubble tests in brine were performed in this study. The results revealed that underivatized MA:NIPMAM in water (as maleic acid:NIPMAM copolymer) showed poor KHI performance, probably due to internal hydrogen bonding. However, derivatization of MA:NIPMAM with 3-(dibutylamino)-1-propylamine (DBAPA) to give MA:NIPMAM-DBAPA gave excellent gas hydrate inhibition performance but only weak corrosion inhibition performance. Unlike some KHI polymers, MA:NIPMAM-DBAPA was compatible with a classic fatty acid imidazoline CI, such that neither the KHI polymer performance nor the corrosion inhibition of the imidazoline was affected. Furthermore, excellent dual gas hydrate and corrosion inhibition was also achieved in blends of MA:NIPMAM-DBAPA with small thiol-based molecules. In particular, the addition of butyl thioglycolate not only gave excellent corrosion inhibition efficiency, better than adding the fatty imidazoline, but also enhanced the overall gas hydrate inhibition performance.

Nuclear Magnetic Resonance Analysis of Hydrothermal Reactions of Ethyl- and Octylamine in Sub- and Supercritical Water

Hydrothermal reactions of aliphatic amines have recently gained importance in relation to the application of amines as film-forming corrosion inhibitors for steam-water cycles. The kinetics and mechanism of the hydrothermal reactions of ethylammomiun cation (EtAH+) and n-octylammonium cation (OctAH+) were studied for comparison with the corresponding neutral amines to elucidate their reaction products and pathways at sub- and supercritical temperatures of 300-400 °C as model reactions of aliphatic ammonium cations. We analyzed the reaction of 13C-15N-labeled EtAH+ using NMR spectroscopy and revealed that the initial hydrolysis to ethanol, known as the main path, is followed by the elimination reaction producing ethene and the disproportionation reaction giving diethylammonium cation. The OctAH+ yields octene and octanol, each of which isomerizes to thermodynamically more stable species as the major products. Comparisons were made between the reactions of the neutral amines and ammonium cations to highlight their different reactivity. The hydrolysis, alkene formation, and dehydration of alcohols to alkenes were all found to be accelerated at low pH. The formation of low-molecular-weight organic acids such as acetic acid and formic acid was not observed. These results indicate that the corrosion protection effect of film-forming amines will be maintained under practical conditions with pH values as high as around 9 to 10, and hence side reactions involving byproducts will be suppressed.

N-Vinyl Caprolactam/Maleic-Based Copolymers as Kinetic Hydrate Inhibitors: The Effect of Internal Hydrogen Bonding

Kinetic hydrate inhibitors (KHIs) have been used for over 25 years to prevent gas hydrate formation in oil and gas production flow lines, but they are some of the most expensive oilfield production chemicals. The main component in KHI formulations is a water-soluble polymer with many amphiphilic groups. Usually, in commercial KHI polymers, the hydrophilic part of these groups is the amide group. In addition, KHI polymers are often incompatible with film-forming corrosion inhibitors. Therefore, we sought to find cheaper but effective KHIs that could also act as a flow line corrosion inhibitor. Continuing earlier work from our group with maleic-based polymers, we have now explored maleic acid/N-vinyl caprolactam (MAcid/VCap) copolymers to introduce VCap, a well-known KHI monomer, together with the cheaper MA monomer. KHI performance screening tests were conducted under high pressure with a structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant-cooling test method. Surprisingly, the MAcid/VCap copolymer showed very poor KHI efficacy. GFN2-xTB molecular dynamics simulations revealed that MAcid/VCap exhibits intra-hydrogen bond networks that trap the polymer morphology in the globular form. In this scenario, the caprolactam ring is encapsulated inside the polymer structure due to the intra-hydrogen bonds and the hydrophobic interactions that minimize its ability to interact with the hydrate surfaces, which significantly reduces the MAcid/VCap kinetic inhibition performance. However, the polymer in such globular forms still displays an important amount of its carboxylic groups exposed to water, which explains the water solubility. In contrast to MAcid/VCap copolymers, maleimide derivatives with dibutylamino end groups were effective KHIs and even better with dibutylamine oxide end groups. A terpolymer of MA/VCap reacted with N,N-dibutylaminopropylamine followed by subsequent oxidation of the end groups to dibutylamine oxide and gave the best performance of any maleic-based polymer reported to date. The combination of caprolactam and dibutylamine oxide groups can be thought of as synergism within the same polymer, akin to the excellent synergy of the separate molecules, tributylamine oxide and PVCap.

In Situ Investigation of Under-Deposit Microbial Corrosion and its Inhibition Using a Multi-Electrode Array System.

Carbon steel pipelines used in the oil and gas industry can be susceptible to the combined presence of deposits and microorganisms, which can result in a complex phenomenon, recently termed under-deposit microbial corrosion (UDMC). UDMC and its inhibition in CO2 ambiance were investigated in real-time using a multi-electrode array (MEA) system and surface profilometry analysis. Maps from corrosion rates, galvanic currents, and corrosion potentials recorded at each microelectrode allowed the visualization of local corrosion events on the steel surface. A marine bacterium Enterobacter roggenkampii, an iron-oxidizing, nitrate-reducing microorganism, generated iron deposits on the surface that resulted in pitting corrosion under anaerobic conditions. Areas under deposits displayed anodic behavior, more negative potentials, higher corrosion rates, and pitting compared to areas outside deposits. In the presence of the organic film-forming corrosion inhibitor, 2-Mercaptopyrimidine, the marine bacterium induced local breakdown of the protective inhibitor film and subsequent pitting corrosion of carbon steel. The ability of the MEA system to locally measure self-corrosion processes, galvanic effects and, corrosion potentials across the surface demonstrated its suitability to detect, evaluate and monitor the UDMC process as well as the efficiency of corrosion inhibitors to prevent this corrosion phenomenon. This research highlights the importance of incorporating the microbial component to corrosion inhibitors evaluation to ensure chemical effectiveness in the likely scenario of deposit formation and microbial contamination in oil and gas production equipment.

Multi-functional oilfield production chemicals: maleic-based polymers for gas hydrate and corrosion inhibition

Several chemical problems can occur during the production of oil and gas through flow lines. This includes corrosion, scale deposition and gas hydrate plugging. Three separate chemicals may be needed to treat these issues. Kinetic hydrate inhibitors (KHIs) are used in cold oil or natural gas production flow lines to prevent the formation and plugging of the line with gas hydrates. They are often injected concomitantly with other production chemicals such as corrosion and scale inhibitors. KHIs are specific low molecular weight water-soluble polymers with amphiphilic groups formulated with synergists and solvents. However, many corrosion inhibitors (CIs) are antagonistic to the KHI polymer, severely reducing the KHI performance. It would be preferable and economic if the KHI also could act as a CI. We have explored the use of maleic-based copolymers as KHIs as well as their use as film-forming CIs. KHIs were tested using a natural gas mixture in high pressure rocking cells using the slow constant cooling test method. A terpolymer from reaction of vinyl acetate:maleic anhydride copolymer with cyclohexy lamine and 3,3-di-n-butylaminopropylamine (VA:MA-60% cHex-40% DBAPA), gave excellent performance as a KHI, better than the commercially available poly(N-vinyl caprolactam) (PVCap). CO2 corrosion inhibition was measured by Linear Polarization Resistance (LPR) in a 1 litre CO2 bubble test equipment using C1018 steel coupons. The new terpolymer gave good CO2 corrosion inhibition in 3.6 wt% brine, significantly better than PVCap, but not as good as a commercial imidazoline-based surfactant corrosion inhibitor. The terpolymer also showed good corrosion inhibition efficiency at high salinity conditions, (density 1.12 g/cm3). VA:MA-60% cHex-40% DBAPA shifted the open-circuit potential to more positive values and significantly decreased the corrosion rate.

Mechanism of degradation of propargyl alcohol by acid-catalysed hydrolysis and corrosion inhibition efficiency of propargyl alcohol intermediates for carbon steel in hydrochloric acid

Acetylenic alcohols are one of the most important groups of film-forming corrosion inhibitors for carbon steel in hydrochloric acid (HCl). The inhibition mechanism of acetylenic alcohols has been widely discussed for more than 50 years, however, it is not well-understood, particularly with regard to the chemical degradation reactions of acetylenic alcohols in HCl solution. In the present paper, proton nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) techniques were used to investigate the mechanism and the rate of degradation of propargyl alcohol in 3.6–10.8 M HCl at 20–95 °C. Several water-soluble products, such as 1-hydroxypropan-2-one, 2-chloroprop-2-en-1-ol, 2,2-dichloropropan-1-ol and 2-chloropropane-1,2-diol were formed via the electrophilic acid-catalysed addition of HCl and water to the alkyne. Some intermediates further polymerize to form water-insoluble polymers, such as poly (propargyl alcohol), poly (allyl alcohol) and poly (acrolein). The hydrolysis half-life constants of propargyl alcohol decreased with increasing HCl concentration and temperature. The inhibition efficiency (η) of propargyl alcohol and its precursors for carbon steel in 3.6 M and 7.83 M HCl was studied. The critical role of acrolein intermediates on the corrosion performance of propargyl alcohol in hydrochloric acid was identified. Products of propargyl alcohol hydrolysis, 1-hydroxypropan-2-one and 2-chloroprop-2-en-1-ol are poor corrosion inhibitors. However, acrolein and its reactive intermediates are good corrosion inhibitors with inhibitor efficiency, η in the range from 97.69 ± 0.4 % for fresh acrolein to η = 97.94 ± 0.8 % for aged acrolein.

The role of ferrite-cementite interface in formation of hierarchical film on carbon steel in CO2-saturated brine

Carbon steels with ferrite-pearlite structures are commonly used materials in many industrial operations, and their protection against corrosion often relies on preventative inhibition measures. Film-forming corrosion inhibitors are known to provide protection to carbon steels in oil and gas productions lines for decades. However, the mechanisms of how these protect against corrosion are not known. Corrosion inhibitor films with hierarchical structures can be protective to the steel surface due to their large surface area and interconnected hierarchical porosity. The compounds that contribute to the formation of hierarchical morphology can be components of corrosion inhibitor formulations.This study demonstrates solution deposition of a hierarchically structured film derived from sodium thiosulphate. The film forms on an AISI 1030 carbon steel (UNS G10300) substrate in CO2-saturated sodium chloride containing solution under ambient conditions. We identified that the hierarchical film derived from sodium thiosulphate occurs originally at the interface of ferrite-cementite phase in pearlite and elucidate the role of oxygen in the formation of the hierarchical structures. These findings are expected to facilitate developments of novel corrosion inhibition strategies, through a controlled growth of surface films at metallic substrates for specific applications, including corrosion protection in oil and gas industry, catalysis and energy-storage applications.

Effect of N-methyl-diethanolamine and film forming corrosion inhibitor on gas hydrate, and empirical modeling for degradation

Chemical inhibition is a common solution to hydrate formation in gas pipelines. Monoethylene glycol (MEG) and kinetic hydrate inhibitor (KHI) are the most commonly used hydrate inhibitors, whilst N-methyl-diethanolamine (MDEA) and film forming corrosion inhibitor (FFCI) are usually used as part of a corrosion control program to go alongside these hydrate inhibitors. In this study, the methane hydrate inhibition performance of MDEA and FFCI in the presence and absence of a hydrate inhibitor were assessed. The study found that both MDEA and FFCI may improve the overall hydrate inhibitory performance of the combined solution. When combined with KHI an increase in induction times was found. FFCI may act as a thermodynamic hydrate inhibitor, and thus enhance the hydrate inhibitory performance alongside MEG. Furthermore, two empirical models were developed to cater for MEG and MDEA + MEG degradation effect on hydrate phase equilibrium temperature, as this effect cannot be simulated in flow assurance prediction software. Moreover, these models and previously developed models were combined wholesomely in the form of an algorithm to determine the hydrate phase equilibrium temperature.

Kinetic aspects of Mg-Al layered double hydroxides influencing smart corrosion protective behavior

The objective is to study the influence of Mg–Al layered double hydroxides (LDHs) reconstruction processes on inhibitor release kinetics and anion exchange properties, emphasizing the importance of the knowledge of these physicochemical properties to manage and optimize intelligent corrosion protective action. LDHs were prepared using two reconstruction methods after hydrotalcite (HT) calcination: i) reconstruction in terephthalic acid (HTCTe), followed by substitution of terephthalate by imidazole (HTCTe-Im) and ii) direct reconstruction in imidazole solution (HTC-Im). Imidazole (Im) is a film-forming corrosion inhibitor that was selected due to its molecule features. XRD showed that terephthalate and Im did not influence network parameters of reconstructed LDHs, but HTC-Im presented better crystallinity. Such difference strongly influence the kinetics of Im release and anion exchange process of the two LDHs. Similar corrosion inhibition efficiencies were measured for both particles by weight loss. However, localized corrosion was evidenced for HTC-Im. It was notable the synergistic effect of HTC-Im and HTCTe-Im mixtures due to the large amount of imidazole released by HTCTe-Im and removal of chloride from solution by HTC-Im. Results also suggested an active role of LDH itself on corrosion inhibition, attributed to pH and solubilization of structural components other than Im.

The use of green Bistorta Officinalis extract for effective inhibition of corrosion and scale formation problems in cooling water system

Bistorta Officinalis extract was thoroughly characterized as an effective green inhibitor for prevention of corrosion and scale formation problems in cooling water system. Electrochemical impedance spectroscopy, DC polarization, weight loss measurement and UV–Vis spectroscopy have been conducted to investigate the mechanism and performance of the proposed inhibitor. The results of this study demonstrated the high corrosion inhibition performance of Bistorta Officinalis extract in cooling water. It was revealed that the inhibition action of this extract is due to adsorption of insoluble Fe2+ complexes over the steel surface which obeys the Langmuir adsorption isotherm and behaves as a mixed-type film forming corrosion inhibitor. In addition, the Bistorta Officinalis extract exhibited an excellent scale inhibition performance of 99.5% which make it an ideal material to prevent the scale formation in cooling water. Accordingly, the Bistorta Officinalis extract could be proposed for effective treatment of cooling water systems.

Evaluation of MEG reclamation and natural gas hydrate inhibition during corrosion control switchover

The breakthrough of formation water increases the risk not only of gas hydrate formation but also of corrosion. Switching between corrosion strategies may be necessary as formation water increases the risk of scale formation in the presence of methyl diethanolamine (MDEA), acetic acid, and cations. The switchover from pH stabilization with MDEA to a film-forming corrosion inhibitor (FFCI) was investigated when studying the effect of pH changes on the removal of MDEA, FFCI, acetic acid, and salts in the reclamation unit. The natural gas hydrate inhibitory performance (35 wt%) of the reclaimed monoethylene glycol (MEG) samples were also assessed. The study found that an optimum operating pH for the whole system was not achievable because of the contrasting pH requirements in the pretreatment and reclamation units. The study recommends operating the pretreatment unit at pH > 8 to precipitate out the divalent salts, and injecting acid before the regeneration unit, which allows for the volatile acetic acid to be removed via the reflux drum. We found that FFCI and MDEA accumulation in the reclamation unit resulted in a highly viscous residue (1430.53 mPa-s) and a discoloration (from brown to very dark brown). Further, new natural gas hydrate equilibria data for reclaimed MEG have been reported. The performance of reclaimed MEG varied compared with that of pure MEG, and was lower at the end of the experiment, whereas MDEA showed a hydrate-inhibiting effect.

Operation of a MEG pilot regeneration system for organic acid and alkalinity removal during MDEA to FFCI switchover

The switch over from pH stabilisation using MDEA to film forming corrosion inhibitors (FFCI) may be beneficial following formation water breakthrough during hydrocarbon transportation and processing to prevent scaling at elevated pH and to extend the operational lifespan of a field. Where formation water is present, organic acids including acetic can be expected within MEG regeneration systems and can impose a corrosion risk together with carbon dioxide. A case study was performed to evaluate the potential of simultaneous removal of organic acids and MDEA/alkalinity during the switch over from pH stabilisation to film forming corrosion inhibitors (FFCI). Experimental testing was conducted using a MEG pilot regeneration plant operated by the Curtin Corrosion Engineering Industry Centre. Sufficient removal of organic acids was achieved to prevent accumulation within the MEG regeneration loop and subsequent corrosion issues through distillation by lowering the pH of the rich glycol feed to six to promote removal of organic acids with the water distillate. Simultaneously, removal of MDEA and reduction of lean glycol alkalinity was achieved through the reclamation system to facilitate FFCI switchover more rapidly than a comparative industrial operational methodology.

Effects of Thermally Degraded Monoethylene Glycol with Methyl Diethanolamine and Film-Forming Corrosion Inhibitor on Gas Hydrate Kinetics

Gas hydrate blockage and corrosion are two major flow assurance problems associated with transportation of wet gas through carbon steel pipelines. To reduce these risks, various chemicals are used. Monoethylene glycol (MEG) is injected as a hydrate inhibitor while methyl diethanolamine (MDEA) and film-forming corrosion inhibitor (FFCI) are injected as corrosion inhibitors. A large amount of MEG is used in the field, which imposes the need for MEG regeneration. During MEG regeneration, rich MEG undergoes thermal exposure by distillation to remove the water. This study focuses on analyzing the kinetics of methane gas hydrate with thermally exposed MEG solutions with corrosion inhibitors at 135–200 °C. The study analyses the hydrate inhibition performance of three different solutions at selected concentrations and pressures (50–300 bar), using a PVT cell and isobaric method. Results established that thermally degraded solutions cause hydrate inhibition drop. However, the inhibition drop was found to be lower...

Emerging surface characterization techniques for carbon steel corrosion: a critical brief review.

Carbon steel is a preferred construction material in many industrial and domestic applications, including oil and gas pipelines, where corrosion mitigation using film-forming corrosion inhibitor formulations is a widely accepted method. This review identifies surface analytical techniques that are considered suitable for analysis of thin films at metallic substrates, but are yet to be applied to analysis of carbon steel surfaces in corrosive media or treated with corrosion inhibitors. The reviewed methods include time of flight-secondary ion mass spectrometry, X-ray absorption spectroscopy methods, particle-induced X-ray emission, Rutherford backscatter spectroscopy, Auger electron spectroscopy, electron probe microanalysis, near-edge X-ray absorption fine structure spectroscopy, X-ray photoemission electron microscopy, low-energy electron diffraction, small-angle neutron scattering and neutron reflectometry, and conversion electron Moessbauer spectrometry. Advantages and limitations of the analytical methods in thin-film surface investigations are discussed. Technical parameters of nominated analytical methods are provided to assist in the selection of suitable methods for analysis of metallic substrates deposited with surface films. The challenges associated with the applications of the emerging analytical methods in corrosion science are also addressed.

Corrosion Behavior of API 5L X52 Steel under High Concentrations of H<sub>2</sub>S/CO<sub>2</sub> Gases

In the present work, the susceptibility of API 5L X52 steel to corrosion processes was evaluated in the presence of high contents of hydrogen sulfide and carbon dioxide. Gravimetric tests and surface analyses were carried out to establish both the corrosion rate and damage type exhibited by the metal. The obtained results indicate that the hydrogen sulfide is the most active gas in the corrosion processes that took place, quite above carbon dioxide. The main observed corrosion products were iron sulfides and the typical damage associated with hydrogen sulfide presence was Sulfide Stress Cracking (SSC). The surface damage evidences the presence of cracks with considerable magnitude and metal loss as consequences of the corrosion processes. Likewise, the presence of oxygen in the system modifies the displayed corrosion type, where corrosion products such as iron oxides and reduction in the number and extent of cracks are observed. On the other hand, the addition of a film-forming corrosion inhibitor based on modified imidazolines eliminates completely the development of cracks, although under certain test conditions, it can favor localized pitting corrosion.

CO2 corrosion control in steel pipelines. Influence of turbulent flow on the performance of corrosion inhibitors

Corrosion associated with aqueous environments containing carbon dioxide (CO2) and/or hydrogen sulphide (H2S), is a well-known phenomenon in oil and gas industries. This type of corrosion is of particular importance in transportation through steel pipelines. This transportation process could involve the movement of a complex mixture of gas and liquids. This moving mixture is in close contact with the inner surface of the steel pipelines and corrosion can occur. It has been demonstrated that this corrosion is influenced by flow.In oil and gas industries, film-forming corrosion inhibitors are the main tool used to control inner corrosion in pipelines. The movement of the environment generates mechanical shear stresses on the surface of the steel that can interfere with the formation of the film. This phenomenon is frequently not taken into account in corrosion control strategies and could cause problems. Despite the importance of this, there are few scientific studies available, which can provide control criteria.This work presents some ideas developed in order to understand the influence of flow on the corrosion process, making emphasis in the corrosion process associated with carbon dioxide (CO2).

Efficiency of film-forming corrosion inhibitors in strong hydrochloric acid under laminar and turbulent flow conditions

The effect of fluid velocity on the corrosion rate of low carbon steel in inhibited 4M HCl at 80°C has been examined. When the inhibitor film fully covers the metal surface, the corrosion rate slightly increases with increasing flow velocity which can be attributed to a partial erosion of the inhibitor film. When the inhibitor film coverage is in the lower range, the corrosion takes place at the diffusion limit and an increase in flow velocity results in a strong decrease in corrosion rate due to an increased rate of mass transport of the corrosion inhibitor to the metal surface.

Assessment of Preferential Weld Corrosion of Carbon Steel Pipework in CO2-Saturated Flow-Induced Corrosion Environments

Preferential weld corrosion (PWC) has posed a problem to the oil and gas industry for a number of years. The general consensus from authors is that environmental effects take precedence over the weld chemical composition and microstructure. Therefore, the primary approach is to ensure the correct corrosion inhibitor selection and application to prevent PWC. Although there has been considerable focus directed toward the effect of flow rate on PWC in inhibited carbon dioxide (CO2)-saturated environments, the consideration of a higher, localized turbulence over the weld material and the implications this has on PWC appears minimal. This paper considers this effect by reviewing the performance of a commercially available, film-forming oilfield corrosion inhibitor using a submerged impinging jet (SIJ). The dual nozzle arrangement of the SIJ allowed a carbon steel parent metal and a 1% Ni, 0.25% Mo weld material to be subjected to the same brine chemistry, but different flow conditions. The velocity over the parent metal was kept constant at 7 m/s while the weld material was subjected to velocities of 7, 8.8, and 11.4 m/s to simulate different severities of turbulence. Galvanic current and linear polarization resistance (LPR) measurements were used to assess the weld resistance to PWC. Although the weld was shown to be cathodic to the parent metal, increasing velocity and turbulence at the weld relative to the parent metal was found to reduce the galvanic current, suggesting increased susceptibility of the weld to corrosion. The addition of inhibitor at 100 ppm accentuated this effect and led to a reversal of the galvanic current when the relative velocities were 7 m/s and 11.4 m/s for the parent metal and weld, respectively. The paper discusses the power of this galvanic technique for prediction of the conditions conducive to accentuating PWC.

Effectiveness of corrosion inhibitor films for the conservation of bronzes and gilded bronzes

Corrosion inhibitors, associated or not with protective coatings, may be a good solution for planned conservation activities in the case of bronze and gilded bronze artworks.In this work, alternatives to BTA for the inhibition of bronzes and gilded bronze are investigated. The experimentation includes a screening of many organic substances as film-forming corrosion inhibitors for a copper alloy reproducing the composition and the microstructure of a Renaissance leaded bronze. The results, obtained after exposure to 3.5wt.% NaCl solution or concentrated artificial rain, show that, if proper curing conditions are adopted, excellent protective properties are offered by 3-mercaptopropyl-trimetoxysilane.

Potential for Measurement of Corrosion-Inhibitor-Micelle Presence as an Indicator of Optimum Dose

Summary This paper discusses the principle and proof of concept of a novel corrosion-management tool based on maintaining optimum corrosion-inhibitor dose in an inhibited environment. Film-forming corrosion inhibitors typically contain active ionic surfactant molecules, which adsorb on surfaces and form a protective barrier against corrosion. Upon saturation of surfaces by the inhibitor, the molecules are found in the aqueous phase as micelles or in the oil phase as reverse micelles. The proposed technique is based on the hypothesis that the presence of these micelles in the water phase could be used to indicate the total surface coverage and, therefore, the optimum dose. The technique has been applied in the laboratory simulating an actual inhibited multiphase production system. Fluorescent markers, which are extremely sensitive to micelle presence, have been developed and used during the laboratory testing. Results were compared with those from standard laboratory techniques, including interfacial tension (IFT) and particle-size analyses (diffraction), in order to determine the efficacy for micelle detection. Corrosion bubble tests were also used to determine any link to inhibitor efficiency. IFT results showed complex events occurring with increasing inhibitor concentration. The IFT vs. inhibitor concentration curve was nonclassical, probably because of the multicomponent nature of inhibitor formulations, but suggested micelle formation at approximately 150 ppm. Fluorescence analysis suggested that micelles formed starting at a 150-ppm dose. Particle-size analysis was consistent with micelle presence beyond this concentration. Separate experiments comparing fluorescence with corrosion rates demonstrated an apparent nonlinear variance with inhibitor concentration, supporting the hypothesis. The analytical comparisons supported the underlying principles of this micelle-detection technology. Development of a portable device is under way and will provide an important new tool for proactive corrosion management in the oil field as well as a useful laboratory qualification method.