CORROSION INHIBITOR COMPOSITION, TRANSPORT FLUID MIXTURE, METHOD FOR CHARGING CORROSION INHIBITOR COMPOSITION, WINZE, AND PIPELINE

Abstract

A corrosion inhibitor composition contains an organic long-chain compound having a polar group and hydrophobic silica. In a method for charging a corrosion inhibitor composition, the corrosion inhibitor composition constituted of a first corrosion inhibitor composition containing an organic long-chain compound having a polar group and a second corrosion inhibitor composition containing hydrophobic silica is charged into a fluid mixture including at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid and water.

Description

TECHNICAL FIELD

The present invention relates to a corrosion inhibitor composition, a transport fluid mixture, a method for charging a corrosion inhibitor composition, a winze, and a pipeline.

Priority is claimed on Japanese Patent Application No. 2018-002918, filed Jan. 11, 2018, the content of which is incorporated by reference.

BACKGROUND ART

A material of an oil extraction pipe (tubing) installed inside a casing in order to derive petroleum or natural gas from an oil layer or a gas layer above ground in a producing well such as an oil deposit from which petroleum is produced or a gas deposit from which natural gas is produced is mainly carbon steel or stainless steel. In addition, as a material of a transport pipe in a pipeline constructed to transport petroleum or natural gas from a producing well to a treatment facility or a delivery terminal, the same carbon steel or stainless steel as that for an oil extraction pipe is employed.

In crude oil or natural gas as mined from underground, a corrosive gas such as carbon dioxide or hydrogen sulfide is included together with moisture. Therefore, in an oil extraction pipe in a producing well or a transport pipe in a pipeline, the corrosion of the inner surface by such a wet corrosive gas needs to be taken into account.

As a method for inhibiting the corrosion of metal on an outer surface of a drill pipe used for the mining development of petroleum or natural gas, for example, Patent Document 1 discloses a method in which, in suppressing the local corrosion of metals, an organic inhibitor (inhibitor) such as a long-chain fatty acid and a hydrocarbon oil such as an aromatic hydrocarbon are added.

In addition, Patent Document 2 discloses a method for suppressing the corrosion of iron-based metal by water in which the corrosion rate by water is decreased by adjusting the concentration of silica in water circulating in a pipe made of iron-based metal.

CITATION LIST

Patent Document

Patent Document 1

Japanese Unexamined Patent Application, First Publication No. 2000-219980

Patent Document 2

Japanese Unexamined Patent Application, First Publication No. 2004-132636

SUMMARY OF INVENTION

Technical Problem

Patent Document 1 describes a method in which an amine-based organic compound or lauric acid is used as an inhibitor and added to drilling mud together with a hydrocarbon oil such as iso-octane or xylene, which does not necessarily satisfy the corrosion inhibition of metal on an inner surface of a drill pipe used for the mining development of petroleum or natural gas.

In the method used in Patent Document 2, a corrosion inhibition effect of hydrophilic silica such as sodium silicate or potassium silicate against water is confirmed, but a corrosion inhibition effect against wet corrosive gas including carbon dioxide, hydrogen sulfide, or the like exposed when used in a facility in a producing well such as an oil deposit in which a crude oil component is present in a mixture form or a gas deposit.

The present invention has been made in consideration of the above-described circumstance, and an object of the present invention is to provide a corrosion inhibitor composition, a transport fluid mixture, a method for charging a corrosion inhibitor composition, a winze, and a pipeline which are capable of sufficiently inhibiting corrosion by wet corrosive gas including carbon dioxide or hydrogen sulfide on an inner surface of an oil extraction pipe in a producing well or a transport pipe in a pipeline.

Solution to Problem

The present invention is characterized by having any of the following aspects.

[1] A corrosion inhibitor composition including: an organic long-chain compound having a polar group; and hydrophobic silica.

[2] The corrosion inhibitor composition according to [1] further including: an organic solvent.

[3] A transport fluid mixture including: at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid; water; and a corrosion inhibitor composition containing an organic long-chain compound having a polar group and hydrophobic silica.

[4] The transport fluid mixture according to [3] or [4], in which the organic long-chain compound having a polar group has one or more selected from nitrogen, oxygen, and sulfur.

[5] The transport fluid mixture according to [3] or [4], in which the corrosion inhibitor composition further includes an organic solvent.

[6] The transport fluid mixture according to [5], in which the organic solvent is a liquid phase at a temperature and a pressure that are transport conditions of the transport fluid mixture.

[7] The transport fluid mixture according to [5] or [6], in which the organic solvent is an aromatic compound.

[8] A method for charging a corrosion inhibitor composition including: a corrosion inhibitor composition charging step of charging a corrosion inhibitor composition into a fluid mixture including at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid and water, in which the corrosion inhibitor composition is constituted of a first corrosion inhibitor composition containing an organic long-chain compound having a polar group and a second corrosion inhibitor composition containing hydrophobic silica.

[9] The method for charging the corrosion inhibitor composition according to [8], in which the second corrosion inhibitor composition further includes an organic solvent.

[10] The method for charging the corrosion inhibitor composition according to [8] or [9], in which, in the corrosion inhibitor composition charging step, the first corrosion inhibitor composition and the second corrosion inhibitor composition are separately charged into the fluid mixture.

[11] A winze including: a tubing having an anticorrosive coating formed on an inner surface thereof by the corrosion inhibitor composition according to [1] or [2].

The winze in the present invention is not limited to a producing well such as an oil deposit or a gas deposit and includes a facility having a pipe for which the corrosion of an inner surface by corrosive gas is concerned such as an injection well for injecting gas or water into the underground or an observation well for observing the underground state during the production of crude oil or natural gas.

[12] A pipeline including: a transport pipe having an anticorrosive coating formed on an inner surface thereof by the corrosion inhibitor composition according to [1] or [2].

The pipeline in the present invention is a facility that transports a mined fossil fuel such as petroleum or natural gas and does not refer to a simple assembly of pipes.

Advantageous Effects of Invention

According to the corrosion inhibitor composition of the present invention and the transport fluid mixture containing the corrosion inhibitor composition of the present invention, it is possible to sufficiently inhibit the corrosion of a member having an inner surface to be exposed to a liquid phase including wet corrosive gas such as an oil extraction pipe in a producing well or a transport pipe in a pipeline.

In addition, according to the method for charging the corrosion inhibitor composition of the present invention, it is possible to sufficiently inhibit the corrosion of a member having an inner surface to be exposed to a liquid phase including wet corrosive gas such as an oil extraction pipe in a producing well or a transport pipe in a pipeline by efficiently dispersing hydrophobic silica.

In addition, in the winze and the pipeline of the present invention, an inner surface of an oil extraction pipe or the transport pipe does not easily corrode. Therefore, it is possible to extend the lifetime of the oil extraction pipe or the transport pipe, and it is possible to suppress the operation cost of a facility.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically showing an example of an oil extraction pipe included in a winze of the present invention.

FIG. 2 is a partial enlarged view of FIG. 1.

FIG. 3 is a schematic view showing individual facilities of an oil deposit intended for the production of petroleum.

FIG. 4 is a schematic view showing an example of a producing well of FIG. 3.

FIG. 5 is a schematic view showing another example of the producing well of FIG. 3.

FIG. 6 is a schematic view showing an example of a pipeline system of FIG. 3.

FIG. 7 is a schematic view showing a device for measuring a corrosion rate, which is used in Test 1.

FIG. 8 is a graph showing results (corrosion inhibition percentage) of Test 1.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an example of an embodiment of the present invention will be described in detail, but the present invention is not interpreted to be limited to this embodiment.

Corrosion Inhibitor Composition

A corrosion inhibitor composition of the present embodiment contains an organic long-chain compound having a polar group capable of providing an electron to metal and hydrophobic silica. The corrosion inhibitor composition of the present embodiment preferably further contains an organic solvent.

Hereinafter, the respective components will be described.

Organic Long-Chain Compound

The organic long-chain compound has a polar group capable of providing an electron to metal and a long-chain hydrophobic group and is referred to as an inhibitor.

As the polar group capable of providing an electron to metal, polar groups including one or more elements selected from the group consisting of nitrogen (N), oxygen (O), and sulfur (S) are included. Specifically, as the polar group, a carboxy group and a salt thereof, a hydroxyl group, a group having basic nitrogen (for example, an amino group or the like) and a salt thereof, a sulfonic acid group and a salt thereof, and the like are exemplified. As the salt, an alkali metal salt, an alkaline-earth metal salt, and the like are exemplified.

In a case where the inner surface of an oil extraction pipe or a pipeline is bare metal, a polar group including nitrogen is preferably selected, and, in a case where a passive film is formed on the inner surface of a pipeline, a carboxy group is preferably selected as the polar group.

The number of the polar groups may be one or more in one molecule or may be two or more in one molecule. In a case where the organic long-chain compound has two or more polar groups, the polar groups may be identical to or different from each other in kind.

As the long-chain hydrophobic group, an alkyl group having 8 to 20 carbon atoms, an alkenyl group having 8 to 20 carbon atoms, and the like are exemplified.

When the polar group supplies an electron to metal, the organic long-chain compound is adsorbed to the metal surface and forms a layer (film). Such an organic long-chain compound is also referred to as “absorptive inhibitor” or “filming amine”.

As the organic long-chain compound, for example, sodium N-dodecanoylsarcosinate, dodecylamine, stearic acid, lauric acid, oleic imidazoline, and the like are exemplified.

In addition, a commercially available product may be used as the organic long-chain compound, and, for example, a water-soluble inhibitor (trade name: “EC1304A”) and an oil-soluble and water-dispersive inhibitor (trade name: “EC1103A”) manufactured by Nalco Champion, and the like are exemplified.

These organic long-chain compounds may be used singly or two or more organic long-chain compounds may be jointly used.

In a facility in a producing well such as an oil deposit in which water and a crude oil component are present in a mixture form or a gas deposit, an amine-based organic long-chain compound having a smaller specific gravity than water is not uniformly dispersed in a water phase and has a possibility of weakening a corrosion inhibition effect in the bottom portion of the water phase in a pipeline or the like having a structure in which oil and water separate from each other.

Therefore, hydrophobic nano-fine particles, which are a hydrophobic compound having a larger specific gravity than water, are more preferably used.

In addition, the organic long-chain compound or the like has a high dispersibility in water and can be uniformly dispersed in a transport fluid mixture described below even when the proportion of water in the transport fluid mixture increases.

Hydrophobic Silica

In the present embodiment, the hydrophobic silica forms an anticorrosive coating together with the organic long-chain compound adsorbed to the metal surface.

The hydrophobic silica is obtained by surface-treating the silica surface with a hydrophobic component. As a component for surface-treating the silica surface, a silane coupling agent, polydimethylsiloxane, and the like are exemplified, and there is no particular limitation. The hydrophobic silica used in the present embodiment has a surface that has been surface-treated in advance with a hydrophobic component and is thus not easily precipitated in a strongly alkaline solution or strongly acidic solution in which a divalent or trivalent ion is present and is uniformly dispersed.

As the hydrophobic silica, hydrophobic silica having a larger specific gravity than water is preferably used, and the specific gravity relative to water (4° C.) is preferably 1.8 to 2.4, and the specific gravity is more preferably 2.0 to 2.2. When the specific gravity relative to water is 1.8 or more, the hydrophobic silica is likely to sink in a water phase at the time of using the corrosion inhibitor composition of the present invention in an oil extraction pipe, a pipeline, or the like in a facility in a producing well such as an oil deposit in which water and a crude oil component are present in a mixture form or a gas deposit, and thus it is possible to impart a corrosion inhibition effect to the bottom portion of the water phase even in a pipeline or the like having a structure in which oil and water separate from each other. When the specific gravity relative to water is 2.4 or less, it is possible to decrease the amount of the hydrophobic silica to be precipitated.

An average particle diameter of the hydrophobic silica is preferably 10 to 15 nm in terms of a BET average particle diameter and more preferably 11 to 12 nm in terms of a BET average particle diameter. When the BET average particle diameter is 10 nm or more, it is possible to disperse the hydrophobic silica in the transport fluid mixture without agglomerating the hydrophobic silica, and, when the BET average particle diameter exceeds 15 nm, the hydrophobic silica easily agglomerates due to a hydrophobic interaction, the secondary agglomerated hydrophobic silica is likely to coarsen and is precipitated.

The BET average particle diameter of the hydrophobic silica can be confirmed using a BET method.

In addition, a surface hydrophobilization rate of the hydrophobic silica is preferably high and is preferably 80% to 100%. In the present embodiment, a hydrophobic silica having a surface hydrophobilization rate of 100% is more preferably used. There is a tendency that, as the surface hydrophobilization rate increases, the corrosion inhibition effect is more significantly exhibited.

A method for measuring the surface hydrophobilization rate of the hydrophobic silica is not particularly limited, and the surface hydrophobilization rate can be approximately estimated from a contact angle of methanol with respect to the hydrophobic silica surface.

The content of the hydrophobic silica in the corrosion inhibitor composition is preferably 3 to 60 parts by mass and more preferably 6 to 40 parts by mass with respect to 100 parts by mass of the organic long-chain compound. When the content of the hydrophobic silica is 3 parts by mass or more, the corrosion inhibition effect is further enhanced. There is a tendency that, as the content of the hydrophobic silica increases, the corrosion inhibition effect is further enhanced; however, when the content exceeds 40 parts by mass, the improvement of the effect hits a peak. When the balance between the corrosion inhibition effect and the manufacturing cost is taken into account, the content of the hydrophobic silica is preferably 60 parts by mass or less.

Organic Solvent

The organic solvent can be used to efficiently disperse the hydrophobic silica.

While described below, the transport fluid mixture in an oil extraction pipe, a pipeline, or the like in a facility in a producing well such as an oil deposit in which water and a crude oil component are present in a mixture form or a gas deposit may contain the corrosion inhibitor composition of the present embodiment. As described above, when the corrosion inhibitor composition of the present embodiment is contained in the transport fluid mixture, the organic solvent is preferably a liquid phase at a temperature and a pressure that are the transport conditions of the transport fluid mixture.

The temperature and the pressure of the transport fluid mixture exhibit intrinsic values in an oil deposit and a gas deposit respectively. As the organic solvent that is a liquid phase at the temperature and the pressure, hydrocarbons having 8 to 20 carbon atoms, paraffin, cycloparaben, naphtha, light oil, heavy oil, crude oil, and an aromatic compound such as a monocyclic aromatic hydrocarbon having one aromatic ring in one molecule or a polycyclic aromatic hydrocarbon having two or more aromatic rings in one molecule are exemplified.

As the organic solvent, a monocyclic aromatic hydrocarbon is preferred, and a monocyclic aromatic hydrocarbon having a boiling point of 60° C. to 200° C. under a pressure condition of 0.1 MPa is particularly preferred since the organic solvent is favorably compatible with the organic long-chain compound, is capable of highly dispersing the hydrophobic silica, and more easily exhibits the (corrosion inhibition) effect of the present embodiment. The boiling point of the monocyclic aromatic hydrocarbon is more preferably 70° C. to 180° C. and still more preferably 80° C. to 150° C. under a pressure condition of 0.1 MPa. Since the (corrosion inhibition) effect of the present embodiment is more easily exhibited when the corrosion inhibitor composition is used at a higher temperature and a higher pressure (for example, a temperature higher than 100° C. and a pressure higher than 10 MPa) (that is, the use of the corrosion inhibitor composition in an environment in which a transport pipe in an oil extraction pipe or a pipeline in a producing well is exposed to a high temperature and a high pressure), as the organic solvent, a polycyclic aromatic hydrocarbon is preferably used, and it is possible to select the use of a polycyclic aromatic hydrocarbon and, as the organic long-chain compound, an amine-based compound such as dodecylamine, stearic acid, or oleic imidazoline in combination.

As the monocyclic aromatic hydrocarbon, for example, benzene (boiling point: 80.1° C.), toluene (boiling point: 110.6° C.), xylene (boiling point: 138° C. to 144° C.), ethylbenzene (boiling point: 136° C.), and the like are exemplified. These monocyclic aromatic hydrocarbons may be used singly or two or more monocyclic aromatic hydrocarbons may be jointly used.

As the polycyclic aromatic hydrocarbon, SOLVESSO 100, SOLVESSO 150, and SOLVESSO 200 manufactured by Exxon Mobil Corporation, and the like are exemplified. These polycyclic aromatic hydrocarbons may be used singly or two or more polycyclic aromatic hydrocarbons may be jointly used.

The content of the organic solvent in the corrosion inhibitor composition is preferably 100 to 2,000 parts by mass and more preferably 300 to 1,500 parts by mass with respect to 100 parts by mass of the organic long-chain compound. When the content of the organic solvent is 100 parts by mass or more, the enhancement of the corrosion inhibition effect by the addition of the organic solvent can be obtained. There is a tendency that, as the content of the organic solvent increases, the corrosion inhibition effect is further enhanced; however, when the content exceeds 2,000 parts by mass, the improvement of the effect hits a peak. When the balance between the corrosion inhibition effect and the manufacturing cost is taken into account, the content of the organic solvent is preferably 1,000 parts by mass or less.

Random Component

The corrosion inhibitor composition of the present embodiment may include a random component as necessary as long as the effect of the present embodiment is not impaired.

As the random component, for example, alcohols having a low molecular weight (specifically, having 1 to 10 carbon atoms) such as ethanol and the like are exemplified. When the corrosion inhibitor composition includes the alcohol having a low molecular weight, the dispersibility of the organic long-chain compound in water is further enhanced.

Action and Effect

The corrosion inhibitor composition of the present embodiment contains the organic long-chain compound and the hydrophobic silica and is thus excellent in terms of corrosion inhibition performance. In addition, when containing the organic long-chain compound, the hydrophobic silica, and the organic solvent, the corrosion inhibitor composition of the present embodiment is superior in terms of corrosion inhibition performance.

Particularly, the corrosion inhibitor composition of the present embodiment exhibits an excellent effect even on a pipe inner surface in which the suppression of corrosion with a corrosion inhibitor of the related art is difficult and oil and water separate from each other and which is wetted by water. Therefore, the corrosion inhibitor composition of the present embodiment is capable of sufficiently inhibiting the corrosion of the inner surface of an oil extraction pipe or a transport pipe. The reason for the corrosion inhibitor composition of the present embodiment being excellent in terms of corrosion inhibition performance is considered as follows.

When an anticorrosive coating is formed on, for example, the inner surface of an oil extraction pipe by the corrosion inhibitor composition of the present embodiment, as shown in FIG. 1, an oil extraction pipe 10 having an anticorrosive coating 12 made of the corrosion inhibitor composition formed on an inner surface 11a of a main body 11 is obtained. Specifically, this anticorrosive coating 12 is considered to be formed as described below as schematically shown in FIG. 2.

First, the polar group of the organic long-chain compound is adsorbed to the inner surface 11a of the main body 11, and a layer (hereinafter, referred to as “A layer”) 12a mainly made of the organic long-chain compound is formed. Furthermore, the hydrophobic silica and the organic solvent are tangled with the hydrophobic group of the organic long-chain compound. For example, in the case of charging the hydrophobic silica and the organic solvent together, a layer (hereinafter, referred to as “B layer”) 12b mainly made of the organic solvent and a layer (hereinafter, referred to as “C layer”) 12c mainly made of the hydrophobic silica are formed on the A layer 12a, thereby forming the anticorrosive coating 12. The anticorrosive coating 12 may be formed by forming the C layer 12c on the A layer 12a, and, in FIG. 2, the A layer 12a, the B layer 12b, and the C layer 12c are differentiated from each other in order to schematically show the anticorrosive coating 12 for description, but interfaces between these layers are not clear.

In addition, in the case of forming the A layer 12a, the B layer 12b, and the C layer 12c, the polar group of the organic long-chain compound is adsorbed to the inner surface 11a of the main body 11 to form the A layer 12a, and the organic solvent tangles with the hydrophobic group of the organic long-chain compound to form the B layer 12b, whereby the corrosion inhibition effect of the organic long-chain compound is enhanced, and a corrosion inhibition property is exhibited. It is considered that, when the C layer 12c is formed by using the hydrophobic silica in addition to the organic long-chain compound and the organic solvent, stability improves, and the corrosion inhibition effect is further enhanced, whereby the corrosion inhibition property improves, and the corrosion of the inner surface of an oil extraction pipe or a transport pipe can be sufficiently inhibited.

In the case of forming the anticorrosive coating 12 by forming the C layer 12c on the A layer 12a, the C layer 12c may be formed by the tangling of the hydrophobic silica with the hydrophobic group of the organic long-chain compound or the B layer 12b and the C layer 12c may be formed by the tangling of an organic solvent derived from a crude oil component being communicated in the main body 11 with the hydrophobic group of the organic long-chain compound together with the hydrophobic silica.

The corrosion inhibitor composition of the present embodiment is preferred as a corrosion inhibitor composition for an oil extraction pipe in a producing well for producing petroleum, natural gas, or the like or a transport pipe in a pipeline for transporting petroleum or natural gas in which the inner surface of the transport pipe or the like is exposed to a liquid phase including wet corrosive gas and is, specifically, used to form an anticorrosive coating on the inner surface of an oil extraction pipe or a transport pipe.

Transport Fluid Mixture

A transport fluid mixture of the present embodiment is used to form an anticorrosive coating in an oil extraction pipe or a pipeline.

The transport fluid mixture of the present embodiment is a fluid passing through an oil extraction pipe, a pipeline, or the like in a producing well such as an oil deposit in which water and a crude oil component are present in a mixture form or a gas deposit and contains at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid, water, and the corrosion inhibitor composition.

The hydrocarbon fluid in the present embodiment includes crude oil as mined, natural gas as mined, and, furthermore, corrosive gas such as carbon dioxide or hydrogen sulfide.

The water in the present embodiment may be groundwater as mined or may be water being added to be introduced to an injection well and accelerate the collection of crude oil and natural gas when crude oil, natural gas, and groundwater do not flow from a producing well.

In the transport fluid mixture of the present embodiment, the corrosion inhibitor composition of the present embodiment can be used even in a state in which the water is groundwater alone and the ratio of the hydrocarbon fluid, which is an oil, is high (for example, oil (hydrocarbon fluid):water=95 to 75 parts by mass:5 to 25 parts by mass and also can be used even after water for accelerating the collection of crude oil and natural gas is added. Specifically, the transport fluid mixture can be used even when the ratio between the oil (hydrocarbon fluid):water=10 to 30 parts by mass:90 to 70 parts by mass. This is realized by adjusting the property and specific gravity of the organic long-chain compound and/or the specific gravity of the hydrophobic silica in the corrosion inhibitor composition of the present embodiment.

Method for Charging Corrosion Inhibitor Composition

In the present embodiment, the corrosion inhibitor composition constituted of the first corrosion inhibitor composition including an organic long-chain compound having a polar group and the second corrosion inhibitor composition including hydrophobic silica is charged into the fluid mixture including the hydrocarbon fluid and water. The second corrosion inhibitor composition may contain an organic solvent and a random component added as necessary. In a case where the second corrosion inhibitor composition contains an organic solvent, a dispersion solution may be prepared in advance by mixing the organic solvent and hydrophobic silica.

The first corrosion inhibitor composition and the second corrosion inhibitor composition including hydrophobic silica are preferably charged separately while the order is not limited.

Particularly preferably, it is preferable to charge the first corrosion inhibitor composition and then charge the second corrosion inhibitor composition because the efficiency of the formation of the anticorrosive coating is improved.

Winze and Pipeline

A winze and a pipeline of the present embodiment includes a steel pipe having an anticorrosive coating formed on an inner surface using the above-described corrosion inhibitor composition of the present embodiment as an oil extraction pipe in a producing well or a transport pipe in a pipeline. The inner surface refers to an inside surface of an oil extraction pipe or a transport pipe and is a surface which crude oil or natural gas including wet corrosive gas comes into contact with.

An outer surface of the oil extraction pipe or the transport pipe may be coated with a coating layer as necessary.

As the coating layer coating the outer surface, for example, a coating layer having a structure in which a primer layer, an adhesive layer, and a polyolefin layer are sequentially laminated from an outer surface side is exemplified. The primer layer is formed of, for example, an epoxy resin. The polyolefin layer is formed of at least one of polyethylene and polypropylene and may be a single layer or a multilayer.

FIG. 1 is a cross-sectional view showing an example of an oil extraction pipe included in the winze of the present embodiment. As described above, the oil extraction pipe 10 in this example has the anticorrosive coating 12 made of the corrosion inhibitor composition formed on the inner surface 11a of the main body 11.

The amount of the organic long-chain compound attached to one square meter of the inner surface 11a of the main body 11 is preferably 0.1 to 3 mg.

In addition, the amount of the hydrophobic silica attached to one square meter of the inner surface 11a is preferably 0.4 mg to 0.9 g.

In addition, the amount of the organic solvent attached to one square meter of the inner surface 11a is 20 mg to 3 g.

What has described above is also true for the amounts of the organic long-chain compound, the hydrophobic silica, and the organic solvent attached to one square meter of the inner surface of the pipeline.

Here, an example of a method for forming the anticorrosive coating 12 on the inner surface 11a of the pipe will be described with reference to FIG. 3. FIG. 3 shows an oil deposit intended for the production of petroleum. The oil deposit includes a producing well 20 that mines crude oil from an underground oil layer 1, a separator 31 that separates an impurity such as natural gas or ground water from non-treated crude oil, an oil storage tank 32 that stores the crude oil from which the impurity is separated, and a pipeline system 34 that transports the crude oil from the oil storage tank 32 to a treatment facility 33.

FIG. 4 shows the structure of, particularly, the producing well 20 in the oil deposit. The producing well 20 includes a tubular casing 21 reaching up to the oil layer 1 and a tubing 22 as an oil extraction pipe passing through the inside of the casing 21. A plurality of small holes is formed on a lower end wall surface of the casing 21.

An entry guide 23 that introduces a produced fluid to the inside of the tubing 22 is connected to a lower end of the tubing 22 reaching the oil layer 1. A winze device 24 including equipment (not shown) such as a valve, a pressure meter, a thermometer, and a blowout inhibition device is attached to an upper end portion of the tubing 22 exposed on the ground.

A first tank 25 and a second tank 51 into which the corrosion inhibitor composition of the present embodiment is fed are connected to the winze device 24. The first corrosion inhibitor composition including the organic long-chain compound having a polar group is introduced from the first tank 25, and the second corrosion inhibitor composition including the hydrophobic silica is introduced from the second tank 51. The first tank 25 and the second tank 51 communicate with the tubing 22 through a charging pipe 26. A pump 27 that pressurizes and supplies the corrosion inhibitor composition to the inside of the tubing 22 is provided in the charging pipe 26.

Crude oil present in the oil layer 1 flows to the inside of the tubing 22 from the entry guide 23. In a case where the pressure of the oil layer 1 is high, the crude oil flows from the winze through the tubing 22; however, in a case where the pressure of the oil layer 1 is low, the crude oil is drawn to the ground using a drawing pump or the like, not shown. The crude oil mined from the oil layer 1 through the tubing 22 is transported to the separator 31 through the winze device 24, temporarily kept in the oil storage tank 32 after the separation of an impurity, and then transported to the treatment facility 33 through the pipeline system 34.

As a method for forming the anticorrosive coating on the inner surface of the tubing 22 using the corrosion inhibitor composition, there are a method in which the production of crude oil is temporarily stopped and then the anticorrosive coating is formed and a method in which the anticorrosive coating is formed while continuing the production of crude oil.

First, the method in which the production of crude oil is stopped and then the anticorrosive coating is formed will be described. The valve in the winze device 24 is closed, thereby making the inside of the tubing 22 a space closed except for the portion of the entry guide 23 at the front end. In the inside of the tubing 22 made to be a closed space, natural gas, ground water, and, furthermore, crude oil as mined including corrosive gas such as carbon dioxide or hydrogen sulfide are sealed. A pump 27 is operated while maintaining this state, thereby charging the corrosion inhibitor composition into the inside of the tubing 22. In a producing well in which the pressure of the oil layer 1 is high and crude oil flows, the corrosion inhibitor composition is pressurized at a pressure higher than that of the oil layer 1 while maintaining the sealing of the tubing 22, thereby charging the corrosion inhibitor composition into the inside of the tubing 22.

In a producing well in which the pressure of the oil layer 1 is low and crude oil does not flow, the corrosion inhibitor composition may be supplied to the inside of the tubing 22 while keeping the valve in the winze device 24 opened.

The corrosion inhibitor composition supplied to the inside of the tubing 22 sinks in the inside of the tubing 22, and, in such a process, the respective components of the organic long-chain compound, the organic solvent, and the hydrophobic silica are attached to the inner surface of the tubing 22, whereby the anticorrosive coating 12 constituted of the A layer 12a, the B layer 12b, and the C layer 12c shown in FIG. 2 is formed.

Next, the method in which the anticorrosive coating is formed on the inner surface of the tubing 22 while continuing the production of crude oil will be described. As shown in FIG. 5, a charging pipe (capillary tube) 26 having so sufficient a length that a front end reaches the entry guide 23 is mounted in the inside of the tubing 22, and the pump 27 is operated as necessary, thereby supplying the corrosion inhibitor composition to the inside of the tubing 22.

The corrosion inhibitor composition is charged into the inside of the tubing 22 from the front end of the charging pipe 26 reaching the entry guide 23, circulates in the inside of the tubing 22 together with the crude oil flowing to the ground from the oil layer 1, and, in such a process, the respective components of the organic long-chain compound, the organic solvent, and the hydrophobic silica are attached to the inner surface of the tubing 22, whereby the anticorrosive coating 12 constituted of the A layer 12a, the B layer 12b, and the C layer 12c shown in FIG. 2 is formed.

With the above-described methods, it is also possible to form the anticorrosive coating 12 on the inner surface of the existing tubing 22 in a producing well.

The anticorrosive coating is formed on the inner surface of the pipeline, for example, as described below.

FIG. 6 shows the pipeline system 34 that transports crude oil to the treatment facility 33 (refer to FIG. 3) from the winze device 24 through the separator 31 and the oil storage tank 32. The pipeline system 34 includes a pneumatic transportation facility 35 that pneumatically transports the crude oil temporarily stored in the oil storage tank toward a refinery, a pipeline 36 connecting a number of transport pipes, and a receiving facility 37 that receives the crude oil pneumatically transported through the pipeline 36 in the refinery.

The first tank 25 and the second tank 51 into which the corrosion inhibitor compositions are fed are connected to the winze device 24. The first tank 25 and the second tank 51 are connected to the winze device 24 through the charging pipe 26 and communicate with the pipeline 36 through the separator 31 and the oil storage tank 32. The pump 27 that pressurizes and supplies the corrosion inhibitor composition to the inside of the pipeline 36 through the winze device 24 is provided in the charging pipe 26.

At the time of forming the anticorrosive coating on the inner surface of the pipeline 36 using the corrosion inhibitor composition, when the corrosion inhibitor composition is charged into the inside of the pipeline 36 through the winze device 24 by operating the pump 27, the corrosion inhibitor composition circulates in the inside of the pipeline 36 together with the crude oil, and, in such a process, the respective components of the organic long-chain compound, the organic solvent, and the hydrophobic silica are attached to the inner surface of the pipeline 36, whereby the anticorrosive coating 12 constituted of the A layer 12a, the B layer 12b, and the C layer 12c shown in FIG. 1 is formed.

With the above-described method, it is also possible to form the anticorrosive coating 12 on the inner surface of a transport pipe configuring the existing pipeline 36.

Because the anticorrosive coating is formed using the corrosion inhibitor composition of the present embodiment on the inner surfaces of the tubing and the pipeline, and thus the winze and the pipeline of the present embodiment described above do not easily corrode.

In addition, in the present embodiment, after the anticorrosive coating is formed on the inner surfaces of the tubing and the pipeline, crude oil or natural gas including wet corrosive gas may be circulated by stopping the circulation of the corrosion inhibitor composition.

That is, because the corrosion inhibitor composition of the present embodiment forms an anticorrosive coating, it is not necessary to circulate the corrosion inhibitor composition while an oil extraction pipe or a pipeline in a facility in a producing well such as an oil deposit or a gas deposit is in operation.

EXAMPLES

Hereinafter, the present invention will be more specifically described, but the present invention is not limited thereto.

Test 1

Example 1

A corrosion rate was measured using a device 40 shown in FIG. 7. The device 40 shown in FIG. 7 was equipped with a sealable glass container 41 having a capacity of 1.0 L (glass cell), addition means 42 for adding a chemical to the glass container 41), charging means 43 for charging a gas such as carbon dioxide into the glass container 41, discharging means 44 for discharging the gas from the glass cell 41, electrodes 45, and stirring means 46.

A heater 41a was attached to an outer circumference of the glass cell 41 so as to be capable of holding the temperature of a solution contained in the glass cell 41 constant.

The electrodes 45 included a reference electrode 45a, an action electrode 45b, and a counter electrode 45c. In the present example, carbon steel electrodes were used as the reference electrode 45a and the action electrode 45b, and platinum was used as the counter electrode 45c.

Sodium hydrogen carbonate was added to a sodium chloride aqueous solution having a concentration of 1% by mass (500 mL) such that the concentration reached 400 mg/L, and hydrochloric acid was added thereto such that the pH reached 3.9 at room temperature (25° C.), thereby preparing a test water.

The full amount of the obtained test water was fed into the glass cell 41, a small current was caused to flow between the reference electrode 45a and the action electrode 45b while stirring the test water in an opened state, a potential difference between the electrodes was controlled to a predetermined set potential (10 mV), and a current density flowing between the action electrode 45b and the counter electrode 45c was measured.

The potential was controlled by sweeping the potential from a corrosion potential toward an anode side at a certain potential sweep rate.

The corrosion rate was obtained using a polarization resistance method on the basis of the obtained results of the potential and the current density. This was regarded as a corrosion rate (r₀) at the time of blank. The corrosion rate (r₀) at the time of blank was 44 mpy.

Separately, the same amount of the test water was fed into the glass cell 41, a first corrosion inhibitor composition including an organic long-chain compound and a second corrosion inhibitor composition including an organic solvent and hydrophobic silica were separately added thereto from the addition means 42, and a corrosion rate (r₁) per amount of the corrosion inhibitor composition added was obtained in the same manner as the corrosion rate (r₀) while stirring the components in an opened state.

A corrosion inhibition percentage at the time of blank (that is, before the addition of a corrosion inhibitor) was regarded as 0%, and a corrosion inhibition percentage after the addition of the corrosion inhibitor was obtained using Expression (1) from the corrosion rate (r₀) and the corrosion rate (r₁). The results are shown in FIG. 8.

Corrosion inhibition percentage (%)={(r₀−r₁)/r0}×100   (1)

Laurylamine (concentration: 2×10⁻⁴ mol/L, specific gravity relative to water: 0.8) was used as the organic long-chain compound, xylene was used as the organic solvent, and ORGANOSILICASOL (TOL-ST, (BET average particle diameter: 10 to 15 nm, surface hydrophobilization rate: 100%, specific gravity relative to water: 2.2)) manufactured by Nissan Chemical Corporation was used as the hydrophobic silica.

Specifically, first, the corrosion rate (r₁) at the time of adding only laurylamine (concentration: 2×10⁻⁴ mol/L) (37 mg) was obtained, and the corrosion inhibition percentage was calculated. The corrosion inhibition percentage in the case of adding only laurylamine was 32%.

Next, the corrosion rate (r₁) at the time of adding ORGANOSILICASOL (2 mg) to xylene (0.1 cc, 80 mg) was obtained, and the corrosion inhibition percentage was calculated. The corrosion inhibition percentage at this time was 32%.

Furthermore, xylene (0.1 cc, 80 mg) and ORGANOSILICASOL (2 mg) were added stepwise, the corrosion rates (r₁) were obtained respectively for ratios of (ORGANOSILICASOL (mg)/xylene (cc) being 4 mg/0.2 cc, 6 mg/0.3 cc, 8 mg/0.4 cc, 10 mg/0.5 cc, 12 mg/0.6 cc, and 14 mg/0.7 cc, and the corrosion inhibition percentages were calculated.

The corrosion inhibition percentages were 56%, 66%, 80%, 86%, 89%, and 91% in order, and the results are shown in FIG. 8.

In Example 1, with respect to 100 parts by mass of the organic long-chain compound, the hydrophobic silica was added stepwise in five parts by mass increments, and the organic solvent was added stepwise in 220 parts by mass increments.

Comparative Example 1

First, only laurylamine (concentration: 2×10⁻⁴ mol/L) (37 mg) was added in the same manner as in Example 1.

After that, the corrosion rates (r₁) at the time of adding, instead of the corrosion inhibitor composition of the present invention, only xylene, which was an organic solvent, (0.2 cc, 0.4 cc, 0.6 cc, and 0.7 cc) were obtained, and the corrosion inhibition percentages were calculated.

The corrosion inhibition percentages were 36%, 59%, 62%, and 64% in order, and the results are shown in FIG. 8.

In Comparative Example 1, with respect to 100 parts by mass of the organic long-chain compound, the organic solvent was added stepwise in 440 parts by mass increments.

As is clear from the results in FIG. 8, in Example 1, due to the addition of the corrosion inhibitor composition of the present invention, the corrosion inhibition percentage increased up to approximately 90% compared with that before the addition of the corrosion inhibitor composition (blank). This result showed that, while being a component that easily disperses in a hydrophobic hydrocarbon fluid, the corrosion inhibitor composition of the present invention dispersed even in water and exhibits a corrosion inhibition effect against wet corrosive gas including carbon dioxide or the like.

On the other hand, in Comparative Example 1, the corrosion inhibition percentage increased to a certain extent (approximately 65%) due to the addition of laurylamine, which was an organic long-chain compound, and xylene, which was an organic solvent, but was poorer compared with that in Example 1.

INDUSTRIAL APPLICABILITY

According to the corrosion inhibitor composition of the present invention, it is possible to sufficient inhibit the corrosion of a member having an inner surface to be exposed to a liquid phase including wet corrosive gas such as an oil extraction pipe in a producing well or a transport pipe in a pipeline in a producing well such as an oil deposit or a gas deposit. In addition, according to the corrosion inhibitor composition of the present invention, in a transport fluid mixture passing through an oil extraction pipe in a producing well, a transport pipe in a pipeline, or the like in a producing well such as an oil deposit or a gas deposit, it becomes possible to exhibit a corrosion inhibition effect against wet corrosive gas even when, for example, the content proportion of water becomes high.

REFERENCE SIGNS LIST

10 Oil extraction pipe

11 Main body

12 Anticorrosive coating

20 Producing well

22 Tubing (oil extraction pipe)

23 Entry guide

34 Pipeline system

36 Pipeline (transport pipe)

Claims

1. A corrosion inhibitor composition comprising:

an organic long-chain compound having a polar group; and

hydrophobic silica.

2. The corrosion inhibitor composition according to claim 1, further comprising:

an organic solvent.

3. A transport fluid mixture comprising:

at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid;

water; and

a corrosion inhibitor composition containing an organic long-chain compound having a polar group and hydrophobic silica.

4. The transport fluid mixture according to claim 3,

wherein the organic long-chain compound having a polar group has one or more selected from nitrogen, oxygen, and sulfur.

5. The transport fluid mixture according to claim 3, wherein the corrosion inhibitor composition further includes an organic solvent.

6. The transport fluid mixture according to claim 5, wherein the organic solvent is a liquid phase at a temperature and a pressure that are transport conditions of the transport fluid mixture.

7. The transport fluid mixture according to claim 5, wherein the organic solvent is an aromatic compound.

8. A method for charging a corrosion inhibitor composition comprising:

a corrosion inhibitor composition charging step of charging a corrosion inhibitor composition into a fluid mixture including at least one hydrocarbon fluid selected from the group consisting of a liquid-phase hydrocarbon fluid and a gas-phase hydrocarbon fluid and water,

wherein the corrosion inhibitor composition is constituted of a first corrosion inhibitor composition containing an organic long-chain compound having a polar group and a second corrosion inhibitor composition containing hydrophobic silica.

9. The method for charging the corrosion inhibitor composition according to claim 8, wherein the second corrosion inhibitor composition further includes an organic solvent.

10. The method for charging the corrosion inhibitor composition according to claim 8, wherein, in the corrosion inhibitor composition charging step, the first corrosion inhibitor composition and the second corrosion inhibitor composition are separately charged into the fluid mixture.

11. A winze comprising:

a tubing having an anticorrosive coating formed on an inner surface thereof by the corrosion inhibitor composition according to claim 1.

12. A pipeline comprising:

a transport pipe having an anticorrosive coating formed on an inner surface thereof by the corrosion inhibitor composition according to claim 1.