Research Progress of Common Corrosion Inhibitors in Oil and Gas Field Exploitation|News|UNPChemicals

March 11, 2026

Research Progress of Common Corrosion Inhibitors in Oil and Gas Field Exploitation

What is a corrosion inhibitor in the context of oil and gas field applications?

A corrosion inhibitor for oil and gas fields is a specialized chemical agent added in small quantities to corrosive production environments (containing substances like CO₂, H₂S, and chloride ions) to significantly slow down or prevent the corrosion of metal equipment and pipelines (such as casings, tubing, and transmission lines). It works through various mechanisms: forming a protective adsorption film on the metal surface to isolate corrosive media; chelating with metal ions to stabilize the surface; or acting as anodic/cathodic inhibitors to block electrochemical corrosion reactions. Widely used types include inorganic inhibitors (e.g., silicates, molybdates) and organic inhibitors (e.g., imidazolines, quaternary ammonium salts), and it is a cost-effective and essential technology for maintaining the operational safety and service life of oilfield assets.

Abstract

Corrosion is an inevitable problem in the process of oil and gas field exploitation. Corrosion inhibitors have the advantages of high efficiency, low cost and convenient application, and play an important role in metal anti-corrosion. This paper summarizes the commonly used inorganic and organic corrosion inhibitors and their inhibition mechanisms in oil and gas field exploitation. Inorganic corrosion inhibitors have a long service life, but have disadvantages such as toxicity, poor environmental adaptability, and easy local corrosion due to insufficient protective film. Organic corrosion inhibitors form dense protective films on metal surfaces through chemical adsorption of heteroatoms or unsaturated bonds with metal atoms, achieving anti-corrosion protection. With the continuous improvement of environmental protection requirements, corrosion inhibitors are developing towards green, environmental protection, high efficiency and economical direction, and green environmental protection corrosion inhibitors will inevitably become the research hotspot in the future.

Corrosion has always been an unavoidable problem in oil and gas field exploitation. With the continuous increase of water cut in oilfield development, the comprehensive water cut of oil wells keeps rising, the salinity of produced water increases sharply, and the corrosion phenomenon of pipeline equipment becomes increasingly serious; severe corrosive gas corrosion exists in the exploitation of oil and gas reservoirs containing CO₂ and H₂S; and hydrochloric acid corrosion occurs in the process of rock acidification. In the integrated system of oil, gas and water, the corrosion problems caused by these situations are waiting to be solved. At present, the main methods of oilfield corrosion control are physical and chemical methods. Physical methods generally improve the corrosion resistance of metal itself by using alloy materials or isolate the metal from corrosive media by using non-metallic coatings and linings. However, physical methods have disadvantages such as high cost of alloy materials, easy damage of anti-corrosion coating and short effective period. Therefore, the relatively economical and effective chemical dosing method for oilfield corrosion prevention is to use corrosion inhibitors.

Up to now, corrosion inhibitors have made great progress. There are many kinds of corrosion inhibitors, which can be divided into inorganic corrosion inhibitors, organic corrosion inhibitors and biological corrosion inhibitors according to their composition. Inorganic corrosion inhibitors dominated by chromate and nitrite, organic corrosion inhibitors dominated by quaternary ammonium salt and imidazoline, and biological corrosion inhibitors dominated by chitosan and starch.

Inorganic corrosion inhibitors have been applied earlier, but they have high requirements for the application environment. Inorganic corrosion inhibitors may even aggravate corrosion and scaling under inappropriate pH or salinity conditions. In addition, inorganic corrosion inhibitors generally have high toxicity and are prone to cause environmental problems. Organic corrosion inhibitors contain a large number of lone pair electrons, which can form chemical adsorption with metal surfaces, and their corrosion inhibition rate is higher than that of inorganic corrosion inhibitors, so they have been favored by researchers. Especially, compounding quaternary ammonium organic corrosion inhibitors with surfactants can achieve obvious corrosion inhibition effect.

At the end of the 20th century, with the development of research on corrosion inhibitors, the sources of corrosion inhibitors have become increasingly extensive. Based on the needs of environmental protection, corrosion inhibitors are developing towards low or even non-toxic biological corrosion inhibitors. Corrosion inhibitors have experienced the iterative upgrading from inorganic to organic, and will continue to develop towards green environmental protection, high efficiency and economy in the future.

At present, inorganic and organic corrosion inhibitors are mainly used in oil and gas field exploitation. Therefore, this paper reviews these two types of corrosion inhibitors.

1 Inorganic Corrosion Inhibitors

Inorganic corrosion inhibitors protect the metal substrate by forming oxide films or precipitation films on the metal surface. Common inorganic corrosion inhibitors can be divided into 5 types, and their advantages, disadvantages and corrosion inhibition mechanisms are shown in Table 1.

Table 1 Advantages, Disadvantages and Corrosion Inhibition Mechanisms of Inorganic Corrosion Inhibitors

Type	Advantages	Disadvantages	Corrosion Inhibition Mechanism
Chromate	Relatively low price, fast film formation, wide applicable temperature range	Toxic and carcinogenic, susceptible to water quality conditions	Forms oxide film, inhibits anode reaction
Phosphate	Good chemical stability, low price, non-toxic	Easy to hydrolyze, hydrolysis products form scale with divalent metal ions, water eutrophication	Forms precipitation film and orthophosphate, inhibits cathode reaction
Nitrite	Low price, good water solubility	Corrosion inhibition effect greatly affected by Cl⁻ and SO₄²⁻, toxic, has environmental impact	Forms oxide film, inhibits anode reaction
Silicate	Low price, no adverse impact on environment	Slow film formation, easy to form porous film, forms silicon scale	Forms precipitation film, inhibits anode reaction
Molybdate	Low toxicity, suitable for high temperature and high pH conditions	Large dosage, high economic cost when used alone	Forms oxide film, inhibits anode reaction

1.1 Chromate Corrosion Inhibitors

Chromate or dichromate-based corrosion inhibitors were first used in anti-corrosion engineering. Chromate and dichromate belong to anodic corrosion inhibitors with strong oxidizing properties, which mainly react with metal ions to form oxides covering the anode end, inhibiting the anodic metal dissolution reaction. Due to the toxicity and carcinogenicity of chromate, and its corrosion inhibition effect is greatly affected by system concentration and pH, its field application is greatly limited.

1.2 Phosphate Corrosion Inhibitors

Traditional phosphate corrosion inhibitors generally use polyphosphate as the main component. Polyphosphate can not only react with metal surface through electrostatic action to form precipitation film, but also play a role in corrosion inhibition and scale inhibition, and is easy to hydrolyze into orthophosphate which can inhibit cathodic reaction. However, when the concentration of divalent metal ions in water is high, the products after polyphosphate hydrolysis will react with divalent metal ions to form precipitation and scaling. In addition, traditional phosphate corrosion inhibitors will also bring problems such as water eutrophication.

1.3 Nitrite Corrosion Inhibitors

Nitrite corrosion inhibitor is a common oxidation film-forming corrosion inhibitor, usually using NaNO₂ as the main component. NaNO₂ can react strongly with carbon steel metal surface to form a dense passivation film, thereby preventing corrosion reaction. Nitrite corrosion inhibitors not only have excellent anti-corrosion performance, but also have the advantages of low price and good water solubility. The dosage of nitrite corrosion inhibitor is related to the concentration of Cl⁻ and SO₄²⁻ in produced water. When the concentration of Cl⁻ and SO₄²⁻ is high and the dosage of nitrite corrosion inhibitor is insufficient, steel corrosion will be accelerated and pitting corrosion is easy to form. In addition, nitrite can be decomposed by acidic substances or bacteria, so it is not suitable for low pH systems and open cooling water systems. Moreover, nitrite is toxic and will cause harm to human body and aquatic organisms.

1.4 Silicate Corrosion Inhibitors

Silicate corrosion inhibitors have the characteristics of abundant resources, non-toxicity, low price, no breeding of bacteria, etc., and are a kind of "environmentally friendly" corrosion inhibitors, generally with Na₂SiO₃ as the main component. After silicate is dissolved in water, it will interact strongly with metal surface to form a dense silicon-oxygen stable film to exert corrosion protection. In addition, silicate will form negatively charged colloidal particles after dissolving in water, which can adsorb positive ions in water to form an electric double layer, and the existence of potential makes crystal nuclei not easy to form, thus achieving the purpose of corrosion inhibition.

1.5 Molybdate Corrosion Inhibitors

The corrosion inhibition mechanism of molybdate is similar to that of chromate, belonging to anodic corrosion inhibitors. Compared with chromate corrosion inhibitors, molybdate corrosion inhibitors have the advantages of extremely low toxicity and little environmental pollution, and have good corrosion inhibition effect under high temperature and high pH conditions. However, molybdate corrosion inhibitors have the problem of large dosage and high economic cost when used alone, so they are usually compounded with phosphate corrosion inhibitors by using the synergistic effect between chemicals.

2 Organic Corrosion Inhibitors

Inorganic corrosion inhibitors have a long application history, but the protective films they form are not dense enough or have poor adhesion, which are prone to local corrosion, environmental pollution or poor environmental adaptability, so their field application is greatly limited. Organic corrosion inhibitors have strong adsorption capacity with metal surface and good corrosion inhibition effect, so they are widely used.

Organic corrosion inhibitors have both hydrophilic and hydrophobic groups at the same time. Hydrophilic groups usually contain unsaturated double bonds, triple bonds or polar groups with high electronegativity such as N, S or -OH; hydrophobic groups usually contain long alkyl chains. Hydrophilic groups adsorb on the metal surface, change the charge distribution on the metal surface, achieve corrosion protection, and can also increase the solubility of compounds to further improve corrosion inhibition performance; while hydrophilic groups adsorb for corrosion protection, hydrophobic groups can form a water-repellent protective film, further hindering the corrosion reaction of metals.

2.1 Imidazoline Corrosion Inhibitors

Imidazoline is an important nitrogen-containing heterocyclic compound, also known as diimidazoline, which has a wide range of biological activities and bactericidal properties, and is widely used in oilfield exploitation and chemical industry as corrosion inhibitors and bactericides. Imidazoline molecules are generally composed of three parts: a five-membered heterocyclic ring containing N atoms, a branch chain R1 with functional groups connected to N, and a long carbon chain branch chain R2. Imidazoline corrosion inhibitors mainly exert corrosion inhibition effect through imidazoline ring and hydrophobic groups. The adsorption sites are mainly N and O heteroatoms with lone pair electrons and π electrons (double bonds conjugated with metal d-orbitals), which makes the corrosion inhibitor molecules provide electrons to the empty d-orbitals of metals (forming coordination bonds), and can also accept electrons provided by metals to form stronger chemical bonds, forming a dense protective film on the metal surface; at the same time, long carbon chains are arranged in space to form a large-area hydrophobic water film.

Yang Huaiyu et al. synthesized 14 alkyl imidazoline compounds with different carbon chain hydrophobic branches and different active group hydrophilic chains, and systematically studied the relationship between imidazoline molecular structure change and corrosion inhibition performance. The results showed that in imidazoline compounds, except for the central imidazoline ring, the change of branch chain length at 1 and 2 positions has a great influence on its corrosion inhibition performance. Yan Wanxin et al. selected two hydrophobic branches with different lengths, and analyzed the influence of branch chain length on adsorption effect through molecular dynamics simulation. The results showed that with the increase of hydrophobic branch chain length, its electron supply capacity is enhanced, which promotes the adsorption of imidazoline molecules on steel surface, confirming the important role of hydrophobic branch chains in corrosion protection.

Yang Jiang et al. synthesized a new type of gemini imidazoline corrosion inhibitor with good corrosion inhibition effect on C1018 carbon steel under 100 ℃ and 0.1 MPa CO₂ conditions. Solomon et al. synthesized imidazoline derivative N-(2-(2-trialkyl-4,5-dihydro-1H-imidazol-1-yl)ethyl)benzamide (NTETD). The results showed that in 15% hydrochloric acid medium, 300 mg/L NTETD corrosion inhibitor had a corrosion inhibition rate of 93.0% on carbon steel; the adsorption of NTETD on steel surface was confirmed by using energy dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. Ghanbari et al. evaluated the corrosion inhibition performance of benzimidazole and 2-methylbenzimidazole and 2-aminobenzimidazole in 1 mol/L phosphoric acid solution by using electrochemical impedance and DC polarization technology, and the corrosion inhibition rates were 69.5%, 62.1% and 51.3% respectively. Imidazoline corrosion inhibitors have attracted the attention of major oil fields at home and abroad due to their advantages of low toxicity and good adaptability to acidic environments. However, imidazoline aqueous solution is unstable in high temperature environment and is prone to hydrolysis reaction to form amides, reducing corrosion inhibition effect, which seriously hinders its application in high temperature oil and gas fields.

2.2 Quaternary Ammonium Salt Corrosion Inhibitors

Quaternary ammonium salt, also known as quaternary ammonium cation and quaternary ammonium base, has four C atoms directly connected to N atoms through covalent bonds, and anions are connected to N atoms through ionic bonds under the action of alkylation reagents. The unique structure of quaternary ammonium salt endows it with emulsification, dispersion, cohesion, wetting, sterilization and anti-corrosion properties, and is widely used in oilfield industry and chemical industry. Quaternary ammonium salt can dissociate larger organic cations and smaller inorganic anions in solution. Cations contain N atoms with high electron density and hydrophobic carbon chains. N atoms can form chemical adsorption with empty d-orbitals of metals, and hydrophobic carbon chains are arranged on the metal surface to form a hydrophobic water film. In addition, quaternary ammonium salt can produce physical adsorption with negatively charged cathode regions of metals, so that the electrostatic repulsion of H⁺ in the acid solution is close to the metal surface, achieving anti-corrosion effect.

In terms of anti-corrosion, simple quaternary ammonium salt cannot reduce the corrosion rate of metals in high-temperature and high-concentration corrosive media, so the use of single quaternary ammonium salt is limited, and mixed quaternary ammonium salt or gemini quaternary ammonium salt corrosion inhibitors are usually used.

Kowsari et al. prepared an imidazoline-based quaternary ammonium salt, and tested the corrosion inhibition performance of imidazoline-based ionic liquid (TSIL) corrosion inhibitor on carbon steel in 1 mol/L HCl solution by using electrochemical impedance spectroscopy (EIS) and dynamic potential polarization curve. The results showed that when the TSIL mass concentration was 100 mg/L and soaked for 2 h, the corrosion inhibition rate reached 93.5%. El Hajjaji et al. investigated the anti-corrosion performance of thiazole quaternary ammonium salts with different alkyl chain lengths. The results showed that increasing the length of alkyl chains can improve its coverage on the metal surface, thereby improving the corrosion inhibition rate of the corrosion inhibitor. In recent years, gemini quaternary ammonium salt corrosion inhibitors have become a research hotspot in corrosion prevention. Gemini quaternary ammonium salt corrosion inhibitors are compounds formed by sharing 1 ion connection between 2 quaternary ammonium salt molecules. Huang Hongbing et al. first applied the quaternary ammonium salt corrosion inhibitor CT2-4 to Sichuan gas fields. As early as 2001, El Achouri et al. studied the corrosion inhibition performance of gemini quaternary ammonium salts, and synthesized 3 gemini quaternary ammonium salt corrosion inhibitors by reacting long carbon chain alkylamines with different lengths with epichlorohydrin. All 3 corrosion inhibitors could achieve more than 90% corrosion inhibition performance on carbon steel in hydrochloric acid medium. In addition, Hegazy et al. used molecular orbital theory simulation and other means to make a theoretical demonstration of the adsorption of gemini quaternary ammonium salts on carbon steel surface.

However, quaternary ammonium salt corrosion inhibitors have certain defects in practical application. The molecular weight of quaternary ammonium salt itself is relatively large. In many studies, the addition amount of quaternary ammonium salt corrosion inhibitor is usually measured in mol/L, so the dosage of quaternary ammonium salt corrosion inhibitor is relatively large, making the agent cost higher.

2.3 Thiourea Corrosion Inhibitors

Thiourea is a class of organic compounds containing imide or methylimide characteristic groups, and its special functional endows thiourea and its complexes with biological and chemical activity, making them widely used in medicine, analytical chemistry and catalytic materials. Thiourea corrosion inhibitors have developed to a certain extent in anti-corrosion protection in recent years due to their advantages of low price, easy synthesis, water solubility, environmental protection and various types.

Thiourea corrosion inhibitors mainly exert corrosion inhibition effect through imide groups. On the one hand, imide groups can provide lone pair electrons through heteroatom N, and can also form stable chemical bonds with metal surfaces through C=N double bonds providing π electrons and empty d-orbitals, forming a stable adsorption film; on the other hand, in acidic corrosion media, imide groups are easily protonated to form -C=NH⁺-, and the anions in the medium are enriched on the metal surface to make the metal surface potential negative, and the corrosion inhibitor is adsorbed on the metal surface through electrostatic action.

Tan Xianchu et al. synthesized a thiourea using benzaldehyde and hydrazine hydrate as raw materials. The research showed that this thiourea had good corrosion inhibition rate on N80 steel in 5% hydrochloric acid medium, and the thermodynamic data calculated in the corrosion inhibition process proved that thiourea was a mixed corrosion inhibitor dominated by anodic corrosion inhibition. Salman et al. synthesized 2 double-chain thioureas for the first time. The research showed that in 5 mmol/L phosphoric acid environment, the corrosion inhibition rates of both double-chain thioureas could reach 93.0%, and the adsorption form was Langmuir adsorption isotherm. Wei Xiaojing et al. synthesized 2 double-chain thiourea corrosion inhibitors XFJ-1 and XFJ-2 by solvent method. In 90 ℃ and 15% hydrochloric acid environment, the corrosion inhibition rates of XFJ-1 and XFJ-2 with 1% mass fraction were 82.9% and 99.5% respectively. In addition, similar to quaternary ammonium salt corrosion inhibitors, thiourea corrosion inhibitors also have the problems of large dosage and high cost.

2.4 Alkynol Corrosion Inhibitors

Alkynol compounds are excellent nonionic surfactants and steel corrosion inhibitors. Alkynol compounds have polar groups such as -OH and C≡C, and their main corrosion inhibition mechanism is similar to that of imidazoline corrosion inhibitors. In addition, the C≡C functional groups of alkynol corrosion inhibitors adsorb on the metal surface and can also undergo chain polymerization to form dimers, trimers and even multi-polymers to deposit into films, which significantly enhances their corrosion inhibition performance.

Tu Sheng et al. synthesized bromo-N-n-octyl-4-(4-hydroxy-2-alkynyl)pyridine (P-8), bromo-N-dodecyl-4-(4-hydroxy-2-alkynyl)pyridine (P-10) and bromo-N-dodecyl-4-(4-hydroxy-2-alkynyl)pyridine (P-12) by covalently bonding alkylpyridine and propargyl alcohol. 3 alkynol corrosion inhibitors were studied. The research showed that all 3 corrosion inhibitors had strong corrosion inhibition effect on X70 steel in 20% hydrochloric acid, and when the concentration of P-12 was 9×10⁻² mol/L, the corrosion inhibition rate reached 99.0%.

3 Conclusion and Prospect

Aiming at the corrosion problem of oil and gas field pipelines, adding chemical corrosion inhibitors is a common treatment method. After reviewing the corrosion inhibitors used in oil and gas fields, it can be found that: ① Inorganic corrosion inhibitors have the disadvantages of toxicity and poor environmental adaptability, and are gradually being replaced in oil and gas production applications; ② Organic corrosion inhibitors have well solved the problems of toxicity of inorganic corrosion inhibitors, and by virtue of their advantages of strong adsorption capacity with metal surfaces and good corrosion inhibition effect, they have gradually occupied a dominant position.

The further development of corrosion inhibitors in oil and gas field exploitation needs to focus on the following issues: ① In-depth study of the adsorption behavior, action mechanism and synergistic effect between corrosion inhibitors of corrosion inhibitor molecules on steel surface, and guide the design and development of new corrosion inhibitor molecules based on this; ② Use non-toxic or low-toxic, widely sourced and low-cost natural compounds or degradable raw materials to develop economical and efficient environmentally friendly corrosion inhibitors, and improve their application scale; ③ Facing the requirements of higher efficiency, more multi-functional and more environmental protection, developing new low-toxic and residual-free environmentally friendly corrosion inhibitors is the focus and development direction of future research.