**5.3 Oil and gas well inhibitor**

Oil well acidification is performed through injecting hydrochloric acid, soil acid (hydrofluoric acid and hydrochloric acid mixture), or other acid solution into stratum, by means of acidic fracturing equipment. After the dissolution of the rock by the acid solution, the enlargement of the penetration channel of the rock in the reservoir, and the treatment of the blocks in the seepage channel or the cause by artificial cracks, the gas passages will be unblocked to achieve the purpose of increasing oil and gas production. For the acidification of carbonate oil and gas layers, these are the following chemical reactions.

Lime petroleum gas rock formation reacts with hydrochloric acid:

$$\text{CaCO}\_3 + 2\text{HCl} \rightarrow \text{CaCl}\_2 + \text{H}\_2\text{O} + \text{CO}\_2\uparrow\tag{1}$$

Dolomite oil and gas layer reacts with hydrochloric acid:

$$\text{MgCa(CO}\_3\text{)}\_2 + 4\text{HCl} \rightarrow \text{CaCl}\_2 + \text{MgCl}\_2 + 2\text{H}\_2\text{O} + 2\text{CO}\_2\uparrow\tag{2}$$

The reaction of sandstone oil and gas layer with soil acid solution:

$$\text{CaAl}\_2\text{Si}\_2\text{O}\_8 + \text{16HF} \rightarrow \text{CaF}\_2 + 2\text{AlF}\_3 + 2\text{SiF}\_4 + 8\text{H}\_2\text{O} \tag{3}$$

Hydrofluoric acid reacts with carbonate:

$$\text{CaCO}\_3 + 2\text{HF} \rightarrow \text{CaF}\_2 + 8\text{H}\_2\text{O} + \text{CO}\_2\uparrow\tag{4}$$

**171**

*Formulation of Corrosion Inhibitors*

ture must be solved.

*DOI: http://dx.doi.org/10.5772/intechopen.88533*

sion inhibitor research has just started.

the research and development of oil acidification inhibitors.

**5.4 Oil field-produced water treatment inhibitor**

puts higher requirements on corrosion inhibition performance.

rock formations is relatively far, and the effect of acidification of the oil wells for improving the production is better. It is popular of acidizing oil wells with high concentration of hydrochloric acid and increasing oil and gas production. However, the corrosion problem caused by the acidic solution at high tempera-

From the 1960s to the 1970s, the oil wells were shallow, generally between 1000 and 2000 m, and the downhole temperature was not high. The acidizing corrosion inhibitors in oil well mainly contained formaldehyde, urotropine, arsenious acid (arsenic) and other compounds. Later, after the compound test, two or more corrosion inhibitors were compounded, such as urotropine + potassium iodide, urotropine + OP, butynediol + potassium iodide, butynediol + OP, butynediol + potassium iodide + OP, etc. The HCI concentration should be not more than 15% (10% in general) and the well temperature does not exceed 80°C. Due to the low acid concentration and temperature, the composite corrosion inhibitor can make the corrosion rate of carbon steel within the allowable conditions of construction. During this period, the acidification operation is not much, and the acid corro-

After 1970s, the ultra-deep wells were above 6000 m, and the downhole temperature was as high as 180–200°C. It has been discovered that the acidification of oil wells with high concentration of hydrochloric acid can significantly increase the effect of oil and gas production. However, in such high-temperature ultra-deep wells, when the acidification is carried out with concentrated hydrochloric acid solution, the acidification inhibitor must be required to protect the mild steel in such concentrated hydrochloric acid at 200°C. Therefore, it played a driving role for

Currently, a variety of alkyl pyridine and quinoline-based benzyl quaternary ammonium salt substances can well disperse in hydrochloric acid and soil acid solution. They can become clear and transparent brown liquid and show very good corrosion inhibition for carbon steel in hydrochloric acid or soil acid solution. They have certain corrosion inhibition effect on ferric ions and are highly corrosive to H2S. They are the concentrated hydrochloric acid acidification corrosion inhibitors with high-temperature resistance of 180–200°C. The ketone amine aldehyde condensate compounded with alkynol compound has good dissolving and dispersing property in hydrochloric acid. It has good corrosion inhibition effect on carbon steel in a hydrochloric acid solution at 105–180°C. The alkynyl oxymethylamine modified derivative also has good corrosion inhibition effect on carbon steel in hydrochloric acid or soil acid. The combination of a ketone aldehyde amine condensate, an alkyne alcohol and a cationic surfactant and a solvent to prepare a solution, is suitable for 15–28% HCl solution at 130°C, which has been applied in oil fields. Growcock and Lopp [5] developed a well-acidified corrosion inhibitor "PPO" (3-phenyl-2-propynyl alcohol), which is used in high-temperature downholes with 1–9 mol/L hydrochloric acid. The corrosion inhibition effect is as high as 99%. **Table 17** lists the types of corrosion inhibitors commonly used in oil fields.

Metal equipment in oil field water injection systems, such as various heat exchangers, pumps, valves, oil casings, and storage tanks, are corroded by sewage, causing corrosion and perforation of equipment. It will cause serious impact on production and even force the oil well to stop production. In the construction of oil well acidification, the development of ultra-deep wells and extremely deep wells

From Eqs. (3) and (4), CaF2 is formed in the reaction of hydrofluoric acid with sandstone. When the concentration of the acid solution is lowered, it precipitates and blocks the pores. While the acid solution contains HCI, it can suppress or reduce the sinking of CaF2 precipitate. This is why hydrofluoric acid and hydrochloric acid are mixed in the soil acid solution. The commonly used soil acid solution is 7% HCI + 3% HF or 12% HCI + 6% HF, depending on the clay composition of the sandstone reservoir containing silicate, quartz or carbonate.

From Eqs. (1) and (2), the higher the concentration of hydrochloric acid, the stronger the ability to dissolved rocks and the less volume of acid required to dissolve a certain volume of carbonate and the residual acid solution, thus the easier it is to be discharged from the formation and the favorable oil and gas output; in addition, high concentration of hydrochloric acid has a longer chemical activity time. Therefore, the concentrated hydrochloric acid solution is chemically activated before it is consumed, and its distance between the

#### *Formulation of Corrosion Inhibitors DOI: http://dx.doi.org/10.5772/intechopen.88533*

*Water Chemistry*

245 g/m<sup>2</sup>

does not exceed 98 g/m<sup>2</sup>

tion construction.

**5.3 Oil and gas well inhibitor**

layers, these are the following chemical reactions.

Hydrofluoric acid reacts with carbonate:

inhibition of acid has a recognized standard according to indoor evaluation. It is generally required that the amount of corrosion of steel in an acidizing operation

Oil well acidification is performed through injecting hydrochloric acid, soil acid (hydrofluoric acid and hydrochloric acid mixture), or other acid solution into stratum, by means of acidic fracturing equipment. After the dissolution of the rock by the acid solution, the enlargement of the penetration channel of the rock in the reservoir, and the treatment of the blocks in the seepage channel or the cause by artificial cracks, the gas passages will be unblocked to achieve the purpose of increasing oil and gas production. For the acidification of carbonate oil and gas

MgCa (CO3)2 + 4HCl → CaCl2 + MgCl2 + 2 H2O + 2 CO2↑ (2)

From Eqs. (3) and (4), CaF2 is formed in the reaction of hydrofluoric acid with sandstone. When the concentration of the acid solution is lowered, it precipitates and blocks the pores. While the acid solution contains HCI, it can suppress or reduce the sinking of CaF2 precipitate. This is why hydrofluoric acid and hydrochloric acid are mixed in the soil acid solution. The commonly used soil acid solution is 7% HCI + 3% HF or 12% HCI + 6% HF, depending on the clay composition of the

From Eqs. (1) and (2), the higher the concentration of hydrochloric acid, the stronger the ability to dissolved rocks and the less volume of acid required to dissolve a certain volume of carbonate and the residual acid solution, thus the easier it is to be discharged from the formation and the favorable oil and gas output; in addition, high concentration of hydrochloric acid has a longer chemical activity time. Therefore, the concentrated hydrochloric acid solution is chemically activated before it is consumed, and its distance between the

Lime petroleum gas rock formation reacts with hydrochloric acid:

The reaction of sandstone oil and gas layer with soil acid solution:

Dolomite oil and gas layer reacts with hydrochloric acid:

sandstone reservoir containing silicate, quartz or carbonate.

; pitting corrosion shall not occur. Since the 1970s, fracturing acid inhibitors have gradually developed into a variety of varieties. The main types of compounds are amines and their derivatives, pyrenes, acetylenic alcohols, etc., and some nonionic surfactants and alcohol solvents are added for the fabrication of a multicomponent formulation. In order to improve the temperature resistance, iodide or telluride is also used as a synergist, and the well temperature can be as high as 204°C to achieve the degree of corrosion inhibition required for acidifica-

; in deep well operations, it is acceptable to not exceed

CaCO3 + 2HCl → CaCl2 + H2O + CO2↑ (1)

CaAl2 Si2 O8 + 16HF → CaF2 + 2 AlF3 + 2 SiF4 + 8 H2O (3)

CaCO3 + 2HF → CaF2 + 8 H2O + CO2↑ (4)

**170**

rock formations is relatively far, and the effect of acidification of the oil wells for improving the production is better. It is popular of acidizing oil wells with high concentration of hydrochloric acid and increasing oil and gas production. However, the corrosion problem caused by the acidic solution at high temperature must be solved.

From the 1960s to the 1970s, the oil wells were shallow, generally between 1000 and 2000 m, and the downhole temperature was not high. The acidizing corrosion inhibitors in oil well mainly contained formaldehyde, urotropine, arsenious acid (arsenic) and other compounds. Later, after the compound test, two or more corrosion inhibitors were compounded, such as urotropine + potassium iodide, urotropine + OP, butynediol + potassium iodide, butynediol + OP, butynediol + potassium iodide + OP, etc. The HCI concentration should be not more than 15% (10% in general) and the well temperature does not exceed 80°C. Due to the low acid concentration and temperature, the composite corrosion inhibitor can make the corrosion rate of carbon steel within the allowable conditions of construction. During this period, the acidification operation is not much, and the acid corrosion inhibitor research has just started.

After 1970s, the ultra-deep wells were above 6000 m, and the downhole temperature was as high as 180–200°C. It has been discovered that the acidification of oil wells with high concentration of hydrochloric acid can significantly increase the effect of oil and gas production. However, in such high-temperature ultra-deep wells, when the acidification is carried out with concentrated hydrochloric acid solution, the acidification inhibitor must be required to protect the mild steel in such concentrated hydrochloric acid at 200°C. Therefore, it played a driving role for the research and development of oil acidification inhibitors.

Currently, a variety of alkyl pyridine and quinoline-based benzyl quaternary ammonium salt substances can well disperse in hydrochloric acid and soil acid solution. They can become clear and transparent brown liquid and show very good corrosion inhibition for carbon steel in hydrochloric acid or soil acid solution. They have certain corrosion inhibition effect on ferric ions and are highly corrosive to H2S. They are the concentrated hydrochloric acid acidification corrosion inhibitors with high-temperature resistance of 180–200°C. The ketone amine aldehyde condensate compounded with alkynol compound has good dissolving and dispersing property in hydrochloric acid. It has good corrosion inhibition effect on carbon steel in a hydrochloric acid solution at 105–180°C. The alkynyl oxymethylamine modified derivative also has good corrosion inhibition effect on carbon steel in hydrochloric acid or soil acid. The combination of a ketone aldehyde amine condensate, an alkyne alcohol and a cationic surfactant and a solvent to prepare a solution, is suitable for 15–28% HCl solution at 130°C, which has been applied in oil fields. Growcock and Lopp [5] developed a well-acidified corrosion inhibitor "PPO" (3-phenyl-2-propynyl alcohol), which is used in high-temperature downholes with 1–9 mol/L hydrochloric acid. The corrosion inhibition effect is as high as 99%. **Table 17** lists the types of corrosion inhibitors commonly used in oil fields.

#### **5.4 Oil field-produced water treatment inhibitor**

Metal equipment in oil field water injection systems, such as various heat exchangers, pumps, valves, oil casings, and storage tanks, are corroded by sewage, causing corrosion and perforation of equipment. It will cause serious impact on production and even force the oil well to stop production. In the construction of oil well acidification, the development of ultra-deep wells and extremely deep wells puts higher requirements on corrosion inhibition performance.


#### **Table 17.**

*Acidification inhibitors commonly used in oil fields and their application conditions.*

It is possible that the effective corrosion inhibitor for industrial circulating cooling water may be not suitable for the treatment of oil field sewage, which containing large concentration of Cl<sup>−</sup>. The typical oil fields in China, such as Shengli, Zhongyuan, Jianghan, Dagang, and Huabei Oilfield, are with the NaCI up to around 200,000 mg/L in the sewage, which also include CO2, H2S, dissolved oxygen, oil stain and miscellaneous, etc. CT2-7 corrosion inhibitor (the main component is organic amine) is mixed with HEDP and 1227, which is the promising reagent for oil field.

## **6. Results and discussion**

Corrosion inhibitors are classified into inorganic corrosion inhibitors and organic corrosion inhibitors according to their composition. Inorganic corrosion inhibitors passivate the metal on the surface of the anode by its inorganic anion or prevent ions from the anode portion of the metal surface from entering the solution, thereby inhibiting corrosion. The organic corrosion inhibitor mainly forms a precipitation film by the reaction between a reactive group on the organic molecule and a metal ion generated during the etching process and suppresses the electrochemical processes of the anode and the cathode. They have good adsorption to

**173**

**Author details**

China

Yun Chen\* and Wenzhong Yang

\*Address all correspondence to: ychen@njtech.edu.cn

provided the original work is properly cited.

School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing,

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Formulation of Corrosion Inhibitors*

**7. Summary conclusion**

*DOI: http://dx.doi.org/10.5772/intechopen.88533*

the metal surface in the corrosive medium. Many corrosion inhibitors containing heteroatoms rely on functional groups to adsorb on the metal surface. The nitrogen atoms in the corrosion inhibitor become cations after quaternization and are easily adsorbed by the negatively charged metal surface to form a monomolecular protective film. The charge distribution and interfacial properties of the metal surface tend to stabilize the energy state of the metal surface. The process can increase the activation energy of the corrosion reaction, slow down the corrosion rate, and greatly inhibit the discharge of hydrogen ion, inhibit the cathode reaction, and effectively improve the corrosion inhibition efficiency of the corrosion inhibitor.

Corrosion inhibitors play an important role in metal protection engineering and the national economic construction. Judging from the current anticorrosion of equipment and other industrial fields, the use of corrosion inhibitors is an effective and economical anticorrosion method. The research on the theory, testing technology, and calculation method of inhibitor has made certain progress, which has promoted the development and application of new corrosion inhibitors.

In the future, the mechanism of the corrosion inhibitor and the relationship between the molecular structure of the corrosion inhibitor and the corrosion inhibition effect should be further developed. More complete and specific environmental performance assessment methods need to be proposed; neural networks, density functional theory, and other computer science, quantum chemistry, and other research methods should be better applied to the development and evaluation of new corrosion inhibitors, and the new high-efficiency corrosion inhibitors should be designed and synthesized. In addition, promote green chemistry and research on the corrosion inhibitors with low-cost and non-polluting chromium-free, zinc-free, lowphosphorus, and even phosphorus-free which is the promising development direction of water treatment corrosion inhibitor. The corrosion inhibitors can be made from natural raw materials, thereby expanding the application range. Furthermore, researchers should pay more attention to the development of multifunctional corrosion inhibitors used in different working conditions. It should focus on the development of copolymer corrosion inhibitors and other multi-purpose corrosion inhibitors that have the properties of scale inhibition, biocidal, and biodegradability.

*Formulation of Corrosion Inhibitors DOI: http://dx.doi.org/10.5772/intechopen.88533*

*Water Chemistry*

**Main chemical composition Acid-base** 

Pyridine slag quaternary ammonium salt 15–20 HCl 70–90 Coal tar pyridine residue extract 15–20 HCl 80–120 Coal tar pyridine residue extract adding dyeing agent 15–28 HCl 90–180 Pyridine hydrochloride residue and surfactant 15–20 HCl 80–120 Ketoamine aldehyde condensate 15–28 HCl 90–150 Imidazoline 15 HCl 90 Imidazoline plus formaldehyde 15–28 HCl 80–150 Pyridine hydrochloride slag + alkyl sulfonate 15–28 HCl 90 MBT, thiourea, OP, and other pyridine residues 7 HCl + 3 HF 30–70 Benzyl quaternary ammonium salt 15–28 HCl 90–190 Pyridine derivatives, formaldehyde, etc. 15–28 HCl 90–120 Cyclohexanone aniline 15–28 HCl 90–180 Ketoamine condensate 15–28 HCl 90–150 Acetophenone aniline, etc. 15–28 HCl 90–160 Pyridine quaternary ammonium salt, etc. 12 HCl + 6 HF 120 Quinoline quaternary ammonium salt, etc. 12 HCl + 6 HF 150

**concentration (%)**

15–28 HCl 196

**Temperature range (°C)**

**172**

**6. Results and discussion**

Alkylpyridine quaternary ammonium salt and other

components

**Table 17.**

It is possible that the effective corrosion inhibitor for industrial circulating cooling water may be not suitable for the treatment of oil field sewage, which

*Acidification inhibitors commonly used in oil fields and their application conditions.*

Ketoamine aldehyde condensate, alkynol, etc. 15–28 HCl 90–130 Imidazoline derivative 15 HCl 90–100 Imidazoline 15 HCl 90 Pyridine quaternary ammonium salt, etc. 15–28 HCl 90–120

Corrosion inhibitors are classified into inorganic corrosion inhibitors and organic corrosion inhibitors according to their composition. Inorganic corrosion inhibitors passivate the metal on the surface of the anode by its inorganic anion or prevent ions from the anode portion of the metal surface from entering the solution, thereby inhibiting corrosion. The organic corrosion inhibitor mainly forms a precipitation film by the reaction between a reactive group on the organic molecule and a metal ion generated during the etching process and suppresses the electrochemical processes of the anode and the cathode. They have good adsorption to

containing large concentration of Cl<sup>−</sup>. The typical oil fields in China, such as Shengli, Zhongyuan, Jianghan, Dagang, and Huabei Oilfield, are with the NaCI up to around 200,000 mg/L in the sewage, which also include CO2, H2S, dissolved oxygen, oil stain and miscellaneous, etc. CT2-7 corrosion inhibitor (the main component is organic amine) is mixed with HEDP and 1227, which is the promising reagent for oil field.

the metal surface in the corrosive medium. Many corrosion inhibitors containing heteroatoms rely on functional groups to adsorb on the metal surface. The nitrogen atoms in the corrosion inhibitor become cations after quaternization and are easily adsorbed by the negatively charged metal surface to form a monomolecular protective film. The charge distribution and interfacial properties of the metal surface tend to stabilize the energy state of the metal surface. The process can increase the activation energy of the corrosion reaction, slow down the corrosion rate, and greatly inhibit the discharge of hydrogen ion, inhibit the cathode reaction, and effectively improve the corrosion inhibition efficiency of the corrosion inhibitor.
