WO2023080168A1

WO2023080168A1 - Chemical liquid for recovering crude oil

Info

Publication number: WO2023080168A1
Application number: PCT/JP2022/041039
Authority: WO
Inventors: 雅也柏原; 貴広大堀; 裕丈北川; 智村上
Original assignee: 日産化学株式会社
Priority date: 2021-11-04
Filing date: 2022-11-02
Publication date: 2023-05-11

Abstract

[Problem] To provide a chemical liquid that is for recovering crude oil, that has excellent salt resistance at high temperature and/or high salt concentration, and that exhibits a high crude oil recovery rate. [Solution] This chemical liquid for recovering crude oil is characterized by containing: a cationic silane compound; an aqueous silica sol having an average particle size of 3-500 nm; and at least one cationic surfactant.

Description

Crude oil recovery chemical

The present invention is used in surfactant flooding among the flooding methods for recovering crude oil by injecting it into the oil reservoir of an inland or offshore oil field ("Enhanced Oil Recovery", hereinafter abbreviated as "EOR"). It relates to a chemical solution for crude oil recovery that is excellent in salt resistance and has a high crude oil recovery rate.

The method of recovering (extracting) crude oil from oil reservoirs employs a three-stage method: primary, secondary, or tertiary recovery (or EOR (enhanced recovery)), in which different recovery methods are applied in chronological order. ing.
The primary recovery method includes the natural oil extraction method, which uses the natural pressure and gravity of the oil reservoir, and the artificial oil extraction method, which uses artificial oil extraction technology such as pumps. The maximum recovery rate is said to be about 20%. Secondary recovery methods include the water flooding method and the oil layer pressure maintenance method, in which water or natural gas is injected to restore oil reservoir pressure and increase oil production after production declines in the primary recovery method. Even if these primary and secondary recoveries are combined, the crude oil recovery rate is about 40%, and most of the crude oil remains in the underground oil layer. Therefore, in order to recover more crude oil, and to recover more crude oil from the oil reservoir where crude oil has already been recovered from the easy recovery part, the tertiary recovery method, that is, the EOR flooding method, is used to enhance crude oil recovery. A method to do so is proposed.

EOR flooding methods include thermal flooding, gas flooding, microbial flooding, and chemical flooding. Chemical flooding is a technology that increases the efficiency of crude oil extraction by injecting a chemical solution according to the purpose into the oil layer, lowering the interfacial tension between the oil layer and the fluid, and improving the fluidity of the crude oil itself. It is classified into polymer flooding method, surfactant flooding method, micelle flooding method, etc., depending on the chemical used.

Surfactant flooding reduces the interfacial tension between crude oil and water by injecting a series of fluids, including a surfactant-based solution, into the reservoir, causing it to become trapped in the reservoir by capillary action. This is an offensive method that extracts the crude oil by flowing it.
In this flooding method, for example, alkylarylsulfonates are used alone as surfactants, or alkylarylsulfonates are used together with cosurfactants and/or adjuvants. Alkyl aryl sulfonates are commonly used not only because they can lower the interfacial tension between oil and water, but also because they exhibit different phase behavior when used with different salt concentrations, as described below. there is That is, at low salt concentrations the alkylaryl sulfonate tends to stay in the aqueous phase, but at high salt concentrations it tends to stay in the oil phase. At mid-point salt concentrations, microemulsions are formed and significant amounts of oil and brine are present in the microemulsion phase, which is known to exhibit high crude oil recovery.
A specific alkylxylene sulfonate has also been proposed as an EOR surfactant having a low interfacial tension (see Patent Document 1).

The micelle flooding method is a method of making a microemulsion from water and crude oil, injecting the microemulsion called a micelle solution into an underground reservoir, and recovering the petroleum. (see Patent Documents 2 to 4). Surfactants used in this method include petroleum sulfonate, alkylallylsulfonate, alkanesulfonate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyhydric alcohol fatty acid ester, alkyltrimethyl Various anionic, nonionic, and cationic surfactants such as ammonium salts are disclosed. Also disclosed is a micelle solution for oil recovery containing an internal olefin sulfonate having 10 to 30 carbon atoms and an α-olefin sulfonate having 10 to 30 carbon atoms (see Patent Document 5).

In the conventional polymer flooding method, Micellar slag (a mixture of petroleum product sulfonates, auxiliaries, salt water and oil) and polymer are both injected, and a stable and high crude oil recovery rate is achieved. In order to achieve this, there has been proposed a crude oil recovery agent comprising a water-soluble polymer and a nonionic surfactant comprising a reaction product of a fatty acid and an alkanolamine and an amide compound which is an alkylene oxide adduct thereof. (See Patent Document 6).

On the other hand, as a method for improving the recovery of crude oil, gas, and water from hydrocarbon reservoirs or oil wells, a 1-100 nm oil mixed in a wetting agent consisting of a hydrocarbon carrier fluid consisting of water or an α-olefin sulfonate is used. A method of injecting nanoparticles (such as silicon dioxide) into hydrocarbon reservoirs or oil wells has been disclosed (see US Pat. In this paper, oil droplets adhering to the rock surface can be obtained by injecting nanoparticles mixed in a wetting agent consisting of water or a hydrocarbon carrier fluid into a hydrocarbon reservoir or oil well to increase the separation pressure. Disclosed is a method for efficiently stripping the
In addition, as a crude oil recovery chemical solution excellent in high temperature salt resistance used in surfactant flooding, a crude oil recovery chemical solution containing a silane compound, an aqueous silica sol, an anionic surfactant, and a nonionic surfactant is disclosed. (See Patent Document 8). In this document, in anticipation of an improvement in the effect of removing crude oil from the rock surface, the oil recovery rate is improved by adding fine particles such as aqueous silica sol (colloidal silica) to the chemical solution for crude oil recovery. .

Japanese Patent No. 5026264 U.S. Pat. No. 3,506,070 U.S. Pat. No. 3,613,786 U.S. Pat. No. 3,740,343 Japanese Patent Publication No. 1-35157 Japanese Patent Publication No. 5-86989 U.S. Publication No. 2010/0096139 WO2019/054414

In order to further demonstrate the effect of improving the recovery rate of crude oil using fine particles such as nanoparticles and colloidal silica described above, it is necessary to stabilize the particles in a chemical solution containing nanoparticles without aggregating or denaturing them. is required. Since underground hydrocarbon reservoirs and the like to which such chemical solutions are applied are under high temperature, chemical solutions containing nanoparticles are required to have heat resistance. When the chemical solution is prepared or used, it may come into contact with not only low-salinity salt water but also high-salinity salt water. .

Also, until now, in order to improve the crude oil recovery of chemical solutions for crude oil recovery, the presence of an anionic surfactant that has the effect of peeling off crude oil adhering to rocks such as sandstone or carbonate in underground or seabed oil reservoirs is indispensable. However, anionic surfactants have poor high-temperature salt resistance and decompose in a short period of time when injected into an oil layer with a high temperature and high salt concentration. Colloidal silica, which is expected to have the above-mentioned oil recovery effect, has poor high-temperature salt resistance when used alone, and when it is injected into a high-temperature, high-salinity oil phase, it gels in a short time, and the oil recovery effect cannot be sufficiently exhibited. As shown in Patent Document 8, although improvements in high-temperature salt resistance of crude oil recovery chemicals have been studied, there is a demand for chemicals having salt resistance at higher temperatures or at higher salinity concentrations.

The present invention provides a chemical solution for oil recovery used in the EOR flooding method in which a chemical solution is injected into the oil layer of an inland or offshore oil field to recover crude oil, and has excellent salt resistance at higher temperatures and/or high salinity concentrations. An object of the present invention is to provide a crude oil recovery chemical with a high recovery rate.

As a result of intensive studies by the present inventors in order to solve the above problems, they focused on cationic surfactants, and found a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants. is superior in heat resistance and salt resistance at high temperatures exceeding 100°C, and salt resistance at high salinity concentrations exceeding 10% by mass, compared to conventional chemical solutions using anionic surfactants. It was found that the chemical solution for crude oil recovery has excellent crude oil recoverability.

That is, as a first aspect, the present invention relates to a chemical liquid for crude oil recovery, characterized by containing a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants. .
As a second aspect, the crude oil according to the first aspect, wherein the aqueous silica sol includes silica particles in which at least part of the cationic silane compound is bonded to the surface of at least part of the silica particles in the sol. It relates to a recovery chemical.
As a third aspect, the cationic silane compound is at least one compound selected from the group consisting of a silane coupling agent having an amino group, an alkoxysilane having an amino group, a silazane having an amino group, and a siloxane having an amino group. It relates to the crude oil recovery chemical solution according to the first aspect or the second aspect.
As a fourth aspect, it relates to the crude oil recovery chemical solution according to any one of the first to third aspects, further comprising an amphoteric surfactant.
As a fifth aspect, it relates to the crude oil recovery chemical solution according to any one of the first to fourth aspects, further comprising a nonionic surfactant.
As a sixth aspect, the aqueous silica sol is contained in an amount of 0.01% by mass to 50% by mass, in terms of silica solid content, based on the total mass of the crude oil recovery chemical solution. It relates to a crude oil recovery chemical according to any one of the aspects.
As a seventh aspect, any one of the first to sixth aspects, wherein the silane compound is contained at a mass ratio of 0.001 to 10.0 with respect to the silica solid content of the aqueous silica sol. 3. It relates to the chemical solution for crude oil recovery described in the above item.
As an eighth aspect, the crude oil recovery according to any one of the first to seventh aspects, wherein the cationic surfactant is selected from the group consisting of alkylamine salts, quaternary ammonium salts and alkylpyridinium salts. related to liquid medicines.
As a ninth aspect, the first aspect to the eighth aspect, wherein the cationic surfactant is contained at a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. It relates to the crude oil recovery chemical solution according to any one of the above.
As a tenth aspect, any one of the fourth aspect to the ninth aspect, wherein the amphoteric surfactant is selected from the group consisting of carboxybetaine salts, 2-alkylimidazoline derivative types, glycine types and amine oxide types. It relates to the described crude oil recovery chemical.
As an eleventh aspect, the fourth aspect to the tenth aspect, wherein the amphoteric surfactant is contained at a mass ratio of 0.001 or more to less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. any one of the above relates to a chemical solution for crude oil recovery.
As a twelfth aspect, the nonionic surfactant has an HLB value of 3.0 or more and 20.0 or less, and
from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyalkylene alkylamines, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters and fatty acid alkanolamides To be elected,
It relates to the crude oil recovery chemical solution according to any one of the fourth to eleventh aspects.
As a thirteenth aspect, the fifth aspect to the twelfth aspect, wherein the nonionic surfactant is contained at a mass ratio of 0.001 or more to less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. It relates to a crude oil recovery chemical according to any one of the aspects.
As a fourteenth aspect, a method for recovering crude oil from underground hydrocarbon-containing formations, comprising:
(a) a step of forcing a crude oil recovery chemical containing a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants into an underground layer;
(b) recovering the crude oil from the production well together with the chemical injected into the underground layer;
about a method comprising
As a fifteenth aspect, in the chemical solution for crude oil recovery, the cationic surfactant is contained in the chemical solution for crude oil recovery in a mass ratio of 0.001 or more to less than 0.4 with respect to the silica solid content. relates to the method according to the fourteenth aspect, wherein
As a sixteenth aspect, it relates to the method according to the fourteenth aspect or the fifteenth aspect, wherein the crude oil recovery chemical further contains an amphoteric surfactant.
As a seventeenth aspect, it relates to the method according to any one of the fourteenth to sixteenth aspects, wherein the crude oil recovery chemical further contains a nonionic surfactant.

The chemical solution for crude oil recovery of the present invention is particularly excellent in heat resistance and salt resistance at high temperatures exceeding 100° C. and salt resistance at high salinity concentrations exceeding 10% by mass. It is a stable chemical that does not cause problems such as gelation even when it is diluted with salt water of high salt concentration and injected into the oil reservoir of an inland or offshore oil field.
Here, salt water is water containing cations such as sodium ions, calcium ions, and magnesium ions, and anions such as chloride ions, carbonate ions, and sulfate ions. ) and formation water (assumed to be used in underground oil reservoirs of inland oil fields).
In addition to the crude oil stripping effect of the cationic surfactant, the crude oil recovery chemical solution of the present invention is expected to improve the crude oil stripping effect from the rock surface due to the wedge effect of the nanosilica particles contained in the chemical solution, resulting in high recovery. It is a crude oil recovery chemical that can recover crude oil at a high rate.

The chemical solution for crude oil recovery targeted by the present invention is often recovered several months after being injected into the underground or seabed oil reservoir. The chemical solution is exposed to salt water containing low to high concentrations of sodium ions, calcium ions, chloride ions, etc. at temperatures as high as 100°C for several months, so it is stable even in unusually harsh environments. Therefore, it is required that the oil recovery effect can be demonstrated.

The crude oil recovery chemical solution of the present invention is characterized by containing a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants.
The chemical solution for crude oil recovery of the present invention exhibits excellent salt resistance at high temperatures and/or high salinity concentrations in salt water such as seawater and formation water containing sodium chloride, calcium chloride, etc. as main components. It can be expected that it will be a chemical solution for crude oil recovery that is excellent in That is, the chemical solution for crude oil recovery of the present invention can be a chemical solution that is excellent in one or both of salt resistance at high temperatures and salt resistance at high salinity concentrations.
Each component will be described in detail below.

<Aqueous silica sol>
Aqueous silica sol refers to a colloidal dispersion system in which an aqueous solvent is used as a dispersion medium and colloidal silica particles are used as a dispersoid, and can be produced by a known method using water glass (aqueous sodium silicate solution) as a raw material. The average particle size of the aqueous silica sol refers to the average particle size of colloidal silica particles as dispersoids.

In the present invention, unless otherwise specified, the average particle size of the aqueous silica sol (colloidal silica particles) refers to the specific surface area measured by the nitrogen adsorption method (BET method) or the Sears method particle size.
The specific surface area diameter (average particle diameter (specific surface area diameter) D (nm)) obtained by measurement by the nitrogen adsorption method (BET method) is obtained from the specific surface area S (m ² /g) measured by the nitrogen adsorption method, It is given by the formula D(nm)=2720/S.
The Sears method particle size is determined according to the literature: G.W. Sears, Anal. Chem. 28(12), 1981, 1956, Rapid Measurement of Colloidal Silica Particle Size. Specifically, the specific surface area of colloidal silica is obtained from the amount of 0.1N-NaOH required to titrate colloidal silica corresponding to 1.5 g of SiO ₂ from pH 4 to pH 9, and the equivalent diameter (specific surface area diameter).
In the present invention, the average particle size of the aqueous silica sol (colloidal silica particles) by the nitrogen adsorption method (BET method) or the Sears method is 3 to 500 nm, or 3 to 300 nm, or 3 to 150 nm, or 3 to 100 nm, or 3 to 30 nm. can be
If the average particle size is smaller than 3 nm, the chemical becomes unstable, which is not preferable. On the other hand, if the average particle size is larger than 500 nm, the pores of the sandstone or carbonate rock existing in the underground oil field layer may be blocked, which is not preferable because the oil recovery performance is deteriorated.

Then, the silica particles of the silica sol in the chemical solution are determined by measuring the average particle size (DLS average particle size) by the dynamic light scattering method, to determine whether the silica particles in the aqueous silica sol are in a dispersed state or in an aggregated state. can determine if there is
The DLS average particle size represents the average value of the secondary particle size (dispersed particle size), and the DLS average particle size in a completely dispersed state is the average particle size (nitrogen adsorption method (BET method) or Sears It is said to be about twice as large as the specific surface area measured by the method, which represents the average value of primary particle diameters). Then, it can be determined that the silica particles in the aqueous silica sol are aggregated as the DLS average particle size increases.
For example, as an example of an aqueous silica sol, an aqueous silica sol manufactured by Nissan Chemical Co., Ltd.: Snowtex (registered trademark) ST-O has an average particle size (BET method) of 10 to 11 nm, and a DLS average particle size of 15 to 20 nm. As shown in Examples described later, the crude oil recovery chemical solution containing this aqueous silica sol and its salt resistance evaluation sample (salt-containing chemical solution) had a DLS average particle size of 25 nm or less. indicates that the silica particles are almost dispersed.

If the chemical solution has good salt resistance at high temperature or high salt concentration, the DLS average particle size after the salt tolerance test is almost the same as the DLS average particle size of the chemical solution. If the ratio of DLS average particle size/chemical solution is 8.0 or less, it indicates that the same dispersion state as that of the chemical solution is maintained even after the salt tolerance test. However, when the chemical solution has poor salt tolerance at high temperature or high salt concentration, the DLS particle size after the salt tolerance test becomes very large, indicating an aggregation state.
In the crude oil recovery chemical solution of the present invention, after performing a high temperature salt resistance test (for example, at 120 ° C. and a salt concentration of 3% by mass for 60 hours), the DLS average particle size after the salt resistance test / the average particle size before the test If the ratio is 1.5 or less (the rate of change in average particle size is 150% or less), it can be judged that the salt resistance at high temperatures is very good.
In addition, in the crude oil recovery chemical solution of the present invention, after conducting a high salt concentration salt resistance test (for example, at room temperature, at a salt concentration of 17% by mass for 7 days), the DLS average particle size after the salt resistance test / the average before the test If the particle size ratio is 1.5 or less (the rate of change in the average particle size is 150% or less), it can be judged that the salt resistance is very good under high salt concentrations.

In the present invention, a commercially available product can be used as the aqueous silica sol. Aqueous silica sol having a silica concentration of 5 to 50% by mass is generally commercially available and is easily available, which is preferable.
As the aqueous silica sol, both alkaline aqueous silica sol and acidic aqueous silica sol can be used, but acidic aqueous silica sol is more preferable.
Commercially available acidic aqueous silica sols include Snowtex (trade name) ST-OXS, ST-OS, ST-O, ST-O-40, ST-OL, ST-OYL, and ST-OZL. -35, MP-4540M (manufactured by Nissan Chemical Industries, Ltd.), and the like.
The silica solid content concentration in the aqueous silica sol to be used is preferably 5 to 55% by mass.
Here, the silica solid content concentration is a value obtained by a calcination method. Specifically, the mass of the calcined residue obtained by calcining the aqueous silica sol at 1000 ° C. for 30 minutes or more is the mass of the aqueous silica sol. is the value obtained by dividing Further, the mass of the firing residue is called "silica solid content".

In the present invention, the aqueous silica sol is preferably contained in an amount of 0.01% by mass to 50.0% by mass, more preferably in terms of silica solid content, based on the total mass of the chemical solution for crude oil recovery. 10.0% by mass to 25.0% by mass, for example 15.0% by mass to 25.0% by mass.

In the crude oil recovery chemical solution of the present invention, at least part of the surface of the silica particles in the aqueous silica sol may be bonded with at least part of the cationic silane compound described later.
In the present invention, "at least part of the cationic silane compound binds to at least part of the surface of the silica particles" means that the cationic silane compound is bound to at least part of the silica particle surface. Well, that is, in addition to the embodiment in which the silane compound is bonded to the surface of the silica particles, the embodiment in which the silane compound partially covers the surface of the silica particles, and the silane compound covers the entire surface of the silica particles. It encompasses aspects.
The particle size of the silica particles in the aqueous silica sol to which the cationic silane compound is bound to the surface can be easily measured by a commercially available device as the dynamic light scattering particle size described above.

<Cationic silane compound>
The crude oil recovery chemical solution of the present invention is characterized by containing a cationic silane compound. The inclusion of the cationic silane compound significantly improves the salt resistance of the aqueous silica sol at high temperatures and/or high salinity concentrations, thereby maintaining the crude oil recovery effect.
Preferred cationic silane compounds include silane coupling agents having amino groups as organic functional groups, alkoxysilanes having amino groups, silazanes having amino groups, and siloxanes having amino groups.

Examples of the silane coupling agent having an amino group include 3-(2-(2-aminoethylamino)ethylamino)propyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N -2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrichlorosilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-amino propylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, etc. is mentioned.

In the chemical solution for crude oil recovery of the present invention, at a ratio of cationic silane compound/aqueous silica sol (silica: SiO ₂ ) = 0.001 to 10.0 in mass ratio with respect to silica solid content in the aqueous silica sol It is preferable that the above silane compound is added. More preferably, it is added at a ratio in which the same mass ratio is 0.05 to 5.0.
If the mass ratio of the cationic silane compound to the silica solid content in the aqueous silica sol is less than 0.001, the chemical solution may have poor salt resistance at high temperatures and/or high salt concentrations, which is not preferred. Even if the same mass ratio is more than 10.0, that is, if a large amount of the silane compound is added, no further improvement in the effect can be expected.

As described above, in the crude oil recovery chemical solution of the present invention, at least part of the cationic silane compound may be bound to a part of the surface of the silica particles in the aqueous silica sol. Silica particles having a cationic silane compound bonded to at least a part of the surface include, for example, silica particles having the surface coated with the silane compound. By using silica particles having a cationic silane compound bonded to at least a part of the surface, for example, silica particles having the surface coated with the silane compound, it is possible to improve the salt resistance of crude oil recovery chemicals at high temperatures and/or high salinity concentrations. It is possible to further improve the performance.
Therefore, in a preferred embodiment, the crude oil recovery chemical solution of the present invention comprises silica particles in which at least a portion of the cationic silane compound is bonded to at least a portion of the surface of the silica particles in the aqueous silica sol. including.

Silica particles in which at least part of the cationic silane compound is bonded to at least part of the surface (hereinafter also referred to as "silica particles surface-treated with a silane compound" in this specification) is an aqueous silica sol. After adding the silane compound to the aqueous silica sol at a ratio of 0.001 to 10.0 by mass of the silane compound with respect to the silica solid content, for example, heat treatment at 50 to 100 ° C. for 1 hour to 20 hours. can be obtained by doing
At this time, the amount of surface treatment with the cationic silane compound, that is, the silane compound bound to the silica particle surface is preferably about 0.1 to 15 particles per 1 nm ² of the silica particle surface.
If the heat treatment temperature is less than 50°C, the rate of partial hydrolysis of the cationic silane compound will be slow and the efficiency of the surface treatment will be poor.
When the heat treatment time is less than 1 hour, the partial hydrolysis reaction of the cationic silane compound is insufficient. No need to lengthen the heating time.

<Cationic surfactant>
One or more cationic surfactants are used in the crude oil recovery chemical solution of the present invention. For example, 1 to 3 cationic surfactants, or 2 to 5 cationic surfactants, or 1 to 2 cationic surfactants, or 2 cationic surfactants can be combined.
In addition, a chemical solution containing two or more kinds of cationic surfactants has a preferable effect of stabilizing the surfactant itself by interpenetrating the surfactants and forming denser micelles (packing effect). can get. Therefore, the cationic surfactant becomes more stable and the oil recovery effect is maintained.

Cationic surfactants include alkylamine salts, quaternary ammonium salts, and alkylpyridinium salts.

Examples of the alkylamine salts include monoalkylamine salts having one alkyl group having 7 to 20 carbon atoms, and alkyl having one alkyl group having 7 to 20 carbon atoms and having 1 to 8 carbon atoms. dialkylamine salts having one group, trialkylamine salts having one or two alkyl groups having 7 to 20 carbon atoms and other alkyl groups having 1 to 8 carbon atoms, and the like. .

Examples of the quaternary ammonium salts include quaternary ammonium chlorides, bromides, iodides, and trifluoromethanesulfonates.
More specifically, quaternary ammonium salts include alkyltrimethylammonium chlorides and dialkyldimethylammonium chlorides having one or two alkyl groups of 7 to 20 carbon atoms; alkyl groups of 7 to 20 carbon atoms; Alkyltrimethylammonium bromide and dialkyldimethylammonium bromide having 1 or 2; Alkyltrimethylammonium iodide and dialkyldimethylammonium iodide having 1 or 2 alkyl groups having 7 to 20 carbon atoms; 7 carbon atoms ammonium alkyltrimethylsulfate, ammonium alkyldimethylethylsulfate, ammonium dialkyldiethylsulfate having 1 or 2 alkyl groups of up to 20; alkylbenzalkonium chloride having an alkyl group of 7 to 20 carbon atoms (also known as alkyldimethylbenzylammonium chloride), etc. is mentioned.
Examples of alkyltrimethylammonium chlorides having 7 to 20 carbon atoms include octyltrimethylammonium chloride, lauryltrimethylammonium chloride, hexadecyltrimethylammonium chloride and stearyltrimethylammonium chloride.
Examples of alkyltrimethylammonium bromides having 7 to 20 carbon atoms include octyltrimethylammonium bromide, lauryltrimethylammonium bromide, hexadecyltrimethylammonium bromide and stearyltrimethylammonium bromide.
Alkyldimethylethylammonium sulfates having 7 to 20 carbon atoms are, for example, octyldimethylethylammonium sulfate (also known as octyldimethylethylammonium sulfate), lauryldimethylethylammonium sulfate (also known as lauryldimethylethylammonium sulfate), palmityldimethylethylammonium sulfate (also known as palmityl dimethylethylammonium sulfate) and the like.
Alkylbenzalkonium chlorides having an alkyl group of 7 to 20 carbon atoms (also known as alkyldimethylbenzylammonium chloride) include, for example, lauryldimethylbenzylammonium chloride.

Examples of the alkylpyridinium salts include chlorides, bromides, iodides, and trifluoromethanesulfonates. More specifically, pyridinium salts include alkylpyridinium chloride having an alkyl group of 1 to 8 carbon atoms; alkylpyridinium bromide having an alkyl group of 1 to 8 carbon atoms; Alkylpyridinium iodide having an alkyl group and the like can be mentioned. Pyridinium chloride having an alkyl group of 1 to 8 carbon atoms includes, for example, methylpyridinium chloride, ethylpyridinium chloride, propylpyridinium chloride, butylpyridinium chloride and butylmethylpyridinium chloride.

In the crude oil recovery chemical solution of the present invention, the cationic surfactant is preferably contained in a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content in the aqueous silica sol. If it is less than 0.001, the salt resistance of the chemical solution at high temperature and/or at high salt concentration is lowered, which is not preferable. Even if it is 0.4 or more, it is not preferable because the salt resistance of the chemical solution at high temperature and/or at high salt concentration is lowered.

<Other surfactants>
The crude oil recovery chemical solution of the present invention may contain an amphoteric surfactant and/or a nonionic surfactant, which will be described later, in addition to the above cationic surfactant. In the present invention, in addition to the cationic surfactant, by making a chemical solution containing either one or both of an amphoteric surfactant and a nonionic surfactant, the cationic surfactant and the amphoteric surfactant and / or Nonionic surfactants interpenetrate with each other to form denser micelles, which provides a more favorable effect of stabilizing the surfactant itself. Therefore, the cationic surfactant, the amphoteric surfactant and/or the nonionic surfactant are stabilized, and the crude oil recovery effect is maintained.

<Amphoteric Surfactant>
In addition to the cationic surfactants described above, one or more amphoteric surfactants may be used in the crude oil recovery chemical solution of the present invention.
For example, amphoteric surfactants include carboxybetaine salts, 2-alkylimidazoline derivative types, glycine types, amine oxide types, and the like.

Carboxybetaine salts include alkylbetaines having 8 to 20 carbon atoms, fatty acid amidopropylbetaines, and the like.
Examples of the alkylbetaine having 8 to 20 carbon atoms include betaine alkyldimethylaminoacetate having 8 to 20 carbon atoms, such as betaine lauryldimethylaminoacetate and betaine stearyldimethylaminoacetate.
Fatty acid amidopropyl betaines include cocamidopropyl betaine, cocamidopropyl hydroxysultaine, and the like.

2-alkylimidazoline derivative types include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaines having 8 to 20 carbon atoms, such as N-lauroyl-N′-carboxymethyl-N '-hydroxyethylethyleneimidazolinium betaine, N-cocoyl-N'-carboxymethyl-N'-hydroxyethylethyleneimidazolinium betaine, 2-cocoyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, 2 -lauryl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, 2-undecyl-N,N,N-(hydroxyethylcarboxymethyl)-2-imidazolinium betaine and the like.

Examples of the glycine type include alkyldiethylenetriaminoacetic acid and dialkyldiethylenetriaminoacetic acid having 8 to 20 carbon atoms.

Amine oxide types include alkylamine oxides having 8 to 20 carbon atoms, such as coconut oil alkyldimethylamine N-oxide, lauryldimethylamine N-oxide, and oleyldimethylamine N-oxide.

In the crude oil recovery chemical solution of the present invention, the amphoteric surfactant is preferably contained in a ratio of 0.001 or more and less than 0.4 with respect to the silica solid content in the aqueous silica sol, that is, silica particles. If it is less than 0.001, the salt resistance of the chemical solution at high temperature and/or at high salt concentration is lowered, which is not preferable. Even if it is 0.4 or more, it is not preferable because the salt resistance of the chemical solution at high temperature and/or at high salt concentration is lowered.

<Nonionic surfactant>
In addition to the cationic surfactants described above, one or more nonionic surfactants may be used in the crude oil recovery chemical solution of the present invention. For example, 1 to 5 nonionic surfactants, or 1 to 4 nonionic surfactants, or 1 to 3 nonionic surfactants, or a combination of 1 to 2 nonionic surfactants , or one nonionic surfactant can be used.

In the present invention, nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyalkylene alkylamines, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, It is selected from sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters and fatty acid alkanolamides.

For example, polyoxyethylene alkyl ethers include polyoxyethylene dodecyl ether (polyoxyethylene lauryl ether), polyoxyethylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene behenyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene isodecyl ether and the like.
Polyoxyalkylene alkyl ethers include polyoxyalkylene lauryl ether, polyoxyalkylene tridecyl ether and the like.
Polyoxyethylene alkylphenyl ethers include polyoxyethylene styrenated phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tribenzylphenyl ether and the like.
Polyoxyalkylenealkylamines include polyoxyethylenehexylamine, polyoxypropylenehexylamine, polyoxyethyleneoctylamine, polyoxypropyleneoctylamine, polyoxyethylenedecylamine, polyoxypropylenedecylamine, polyoxyethylenedodecylamine, Polyoxypropylene dodecylamine, polyoxyethylene oleylamine, polyoxypropylene oleylamine, polyoxyethylene laurylamine, polyoxypropylene laurylamine, polyoxyethylene stearylamine, polyoxypropylene stearylamine, polyoxyethylene beef tallow amine, polyoxypropylene beef tallow amines and the like, but are not limited to these;
Alkyl glucosides include decyl glucoside and lauryl glucoside.
Polyoxyethylene fatty acid esters include polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, polyethylene glycol diolate, polypropylene glycol diolate, and the like.
Sorbitan fatty acid esters include sorbitan monocaprylate, sorbitan monolaurate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan There are monosesquioleates and their ethylene oxide adducts.
Polyoxyethylene sorbitan fatty acid esters include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene Examples include ethylene sorbitan trioleate and polyoxyethylene sorbitan triisostearate.
Fatty acid alkanolamides include coconut oil fatty acid diethanolamide, beef tallow fatty acid diethanolamide, lauric acid diethanolamide, and oleic acid diethanolamide.
Furthermore, polyoxyalkyl ethers or polyoxyalkyl glycols such as polyoxyethylene polyoxypropylene glycol, polyoxyethylene fatty acid ester, polyoxyethylene hydrogenated castor oil ether, sorbitan fatty acid ester alkyl ether, alkyl polyglucoside, sorbitan monooleate, sho Sugar fatty acid esters and the like can also be used.
Among the nonionic surfactants, polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers are more preferable because they have good salt resistance at high temperature and/or high salt concentration of chemical solutions.

The HLB value of a nonionic surfactant is a numerical value that represents the balance between hydrophobicity and hydrophilicity. HLB = 0 for a substance without a hydrophilic group, and HLB = 20 for a substance with only a hydrophilic group without a hydrophobic group. .
In the present invention, it is preferable to use a nonionic surfactant having an HLB value of 3.0 or more and 20.0 or less. From the viewpoint of salt tolerance at high temperature and/or high salt concentration of the chemical solution, it is more preferable to use a nonionic surfactant with an HLB value of 10.0 or more and 20.0 or less. Furthermore, from the viewpoint of human health and environmental safety, use a nonionic surfactant with an HLB value of 14.0 or more and 20.0 or less, which is not harmful to the aquatic environment for a long time and has no concerns about so-called endocrine disruptors. is more preferable. Also, when using two or more types of nonionic surfactants with different HLB values, the HLB value of the mixture obtained from the weight average of the HLB value and the blending ratio is adjusted to 10.0 or more and 20.0 or less. preferably.
When the HLB value is less than 3.0, the hydrophobicity of the nonionic surfactant is strong, so in the prepared chemical solution, the aqueous silica sol and the cationic surfactant and the nonionic surfactant do not mix and separate into two layers. Therefore, it is not preferable.

In the crude oil recovery chemical solution of the present invention, the nonionic surfactant is preferably contained in a mass ratio of 0.001 or more to less than 0.4 with respect to the silica solid content in the aqueous silica sol. . By blending in the above ratio, crude oil recoverability can be improved.
It should be noted that both chemical solutions containing only one type of nonionic surfactant and chemical solutions containing two to five types of nonionic surfactants have excellent salt resistance at high temperatures and/or high salinity concentrations, Good crude oil recovery is obtained.

<Other ingredients>
Water-soluble polymers such as hydroxyethylcellulose and its salts, hydroxypropylmethylcellulose and its salts, carboxymethylcellulose and its salts, pectin, guar gum, xandhan gum, tamarind gum, carrageenan, etc. may be further added to increase the viscosity of the liquid medicine. .

The chemical solution for crude oil recovery of the present invention is obtained by using an aqueous silica sol and a cationic silane compound in combination. It is considered that the chemical solution has improved compatibility between the silica particles and the surfactant in the aqueous silica sol. Furthermore, by combining one or more cationic surfactants, it is believed that a crude oil recovery chemical solution with excellent salt resistance at high temperatures and/or high salinity concentrations can be obtained.

<Crude oil recovery method>
The crude oil recovery chemical of the present invention is useful as a crude oil recovery chemical for recovering crude oil from production wells by injecting it into underground formations from injection wells in order to recover crude oil from underground hydrocarbon-containing layers. The injection well and the production well may be the same.
That is, the crude oil recovery chemical of the present invention is used in a method for recovering crude oil from underground hydrocarbon-containing layers. A method of recovering crude oil can be implemented including the step of recovering crude oil from a production well together with the chemical solution injected into the formation. A method for recovering said crude oil is also subject of the present invention.
The crude oil recovery method of the present invention is carried out by including the cationic surfactant in the crude oil recovery chemical solution in a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content. obtain.
The chemical solution for crude oil recovery of the present invention can be used either acidic or alkaline.

The following will describe in more detail based on Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited by these Examples.

(measuring device)
Analysis of the aqueous silica sol prepared in Synthesis Example (pH value, electrical conductivity, DLS average particle size), and analysis of chemical solutions produced in Examples and Comparative Examples (pH value, electrical conductivity, viscosity, DLS average particle size (diameter), and samples prepared using the chemical solution after salt tolerance test at high temperature or high salt concentration were analyzed using the following equipment.
- DLS average particle size (dynamic light scattering particle size): A dynamic light scattering particle size measuring device, Zetasizer Nano (manufactured by Spectris Co., Ltd., Malvern Division) was used.
- pH: A pH meter (manufactured by Toa DKK Co., Ltd.) was used.
- Electric conductivity: An electric conductivity meter (manufactured by Toa DKK Co., Ltd.) was used.
- Viscosity: A B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) was used.
· Surface tension: A surface tension meter DY-500 (manufactured by Kyowa Interface Science Co., Ltd.) was used.
•Silica solid content: Determined from the calcination residue obtained by calcining the aqueous silica sol at 1000°C for 30 minutes or more. Also, the value obtained by dividing the mass of the firing residue by the mass of the aqueous silica sol was defined as the silica solid content concentration.
- Silane compound bond amount: Organic trace element analyzer CHNS/O analyzer (PerkinElmer Japan Co., Ltd.) or TN measuring device TN-2100V Total Nitrogen Analyzer (Mitsubishi Chemical Analytech Co., Ltd.) was used.

[Evaluation of chemical solution for crude oil recovery]
(Silane compound bond amount evaluation-1)
<Washing>
2 g of the aqueous silica sol and 4 g of pure water produced in Synthesis Examples 1 to 3 described later were added to a 15 mL centrifugal filter unit Amicon Ultra 15 (Merck Co., Ltd.), and centrifuged at a centrifugal force of 2770 G for 20 minutes. bottom. After centrifugation, the liquid discharged to the bottom of the unit is discarded, and the same mass of pure water as the discarded liquid is added to the concentrated aqueous silica sol on the filter for re-dispersion, and then again at a rotation speed of 3,000 G. Centrifuged for 20 minutes. The above operations were repeated four times in total to obtain an aqueous silica sol from which excess silane compounds (not bonded to the silica sol) and lactic acid added during sol preparation were removed.
<Measurement of nitrogen content>
The amount of nitrogen in the washed aqueous silica sol was measured with a TN measuring device, and the amount of binding of the silane compound was calculated by the following formula from the obtained amount of nitrogen.

(Silane compound bond amount evaluation-2)
<Washing>
2 g of the aqueous silica sol produced in Synthesis Example 4 described later and 4 g of pure water were placed in a 15 mL centrifugal filter unit Amicon Ultra 15 (Merck Inc.) and centrifuged at a centrifugal force of 2770 G for 20 minutes. After centrifugation, the liquid discharged to the bottom of the unit is discarded, and the same mass of pure water as the discarded liquid is added to the concentrated aqueous silica sol on the filter for re-dispersion, and then again at a rotation speed of 3,000 G. Centrifuged for 20 minutes. The above operations were repeated four times in total to obtain an aqueous silica sol from which excess silane compounds (not bonded to the silica sol) and lactic acid added during sol preparation were removed.
<Measurement of carbon content>
The washed aqueous silica sol was dried by heating at 100° C. and pulverized in a mortar to obtain silica sol powder. The carbon content of the obtained silica sol powder was measured with an organic trace element metal analyzer, and the binding amount of the silane compound was calculated from the obtained carbon content by the following equation.

(Salt resistance evaluation -1)
After putting 2408 g of pure water into a 3 L polyethylene container, 92 g of seawater powder (trade name: Marine Art SF-1, manufactured by Tomita Pharmaceutical Co., Ltd.) was added to prepare salt water 1. After putting a stirrer into a 200 mL styrene bottle, each chemical solution produced in the following examples or comparative examples, pure water and salt water 1 were added while stirring with a magnetic stirrer to obtain a salt concentration of 3% by mass and a silica concentration of 0.5. 150 g of the mixed liquid was prepared so as to be mass % and stirred for 1 hour. This was used as salt water test sample 1 for evaluating the heat resistance and salt resistance of the chemical solution in salt water 1 . The resulting salt water test sample 1 (salt resistance evaluation sample) was evaluated for pH, electric conductivity, and DLS average particle size of aqueous silica sol (silica particles) in the sample.
80 g of the above salt water test sample 1 is placed in a 120 mL Teflon (registered trademark) container that can be sealed, and after sealing, the Teflon (registered trademark) container is placed in a dryer at 120 ° C. and held at 120 ° C. for a predetermined time. The appearance, pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the salt water test sample 1 were evaluated.
The evaluation of high-temperature salt resistance is carried out after holding at 120 ° C. for a predetermined time (after 60 hours), and determining salt resistance based on the measurement results of the DLS average particle size of the aqueous silica sol (silica particles) in the sample (below <Salt resistance Judgment> See) and evaluation of appearance.

(Salt resistance evaluation -2)
After putting 826 g of pure water into a 1 L polystyrene container, 103 g of sodium chloride, 60 g of calcium chloride, 11 g of magnesium chloride, and 0.4 g of sodium sulfate were added to prepare salt water 2 (salt concentration: 17.4%). After putting a stirrer in a 200 mL styrene bottle, each chemical solution produced in the following examples or comparative examples, pure water, and salt water 2 with a salt concentration of 17.4% were added while stirring with a magnetic stirrer to obtain a salt concentration of 17 mass. %, and 150 g of a mixed liquid was prepared so that the silica concentration was 0.5% by mass, and stirred for 1 hour. This was used as salt water test sample 2 for evaluating the salt resistance of the chemical solution in salt water 2 (high salt concentration). The resulting salt water test sample 2 (salt resistance evaluation sample) was evaluated for pH, electric conductivity, and DLS average particle size of aqueous silica sol (silica particles) in the sample.
The salt water test sample 2 was allowed to stand at room temperature for a predetermined time, and the appearance, pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the sample were evaluated.
The evaluation of salt tolerance at a high salt concentration (salinity concentration of 17% by mass) is based on the measurement results of the DLS average particle size of the aqueous silica sol (silica particles) in the sample after being held at room temperature for a predetermined time (7 days). (see <Determination of Salt Tolerance> below) and appearance.
<Determination of salt tolerance>
A: The ratio of the DLS average particle size after the salt tolerance test/the DLS average particle size before the test is 1.5 or less.
B: The ratio of the DLS average particle size after the salt resistance test/the DLS average particle size before the test is 1.6 to 8.0.
C: The ratio of the DLS average particle size after the salt tolerance test/the DLS average particle size before the test is 8.1 or more. Alternatively, the silica sol was gelled to form a white precipitate, and the DLS particle size could not be measured.
The results of the salt tolerance test show that A is the most favorable, followed by B and C in that order.

[Preparation of chemical solution for crude oil recovery: preparation of aqueous sol]
(Synthesis example 1)
Aqueous silica sol (Snowtex (registered trademark) ST-O manufactured by Nissan Chemical Co., Ltd., silica solid content concentration = 20.5% by mass, BET method average particle size 11.0 nm, DLS average particle size 17.2 nm) and 400 g of a magnetic stirrer were added, and then 91.0 g of lactic acid (manufactured by Kanto Chemical Co., Ltd., purity 92%) was added to the silica in the aqueous silica sol while stirring with a magnetic stirrer. Stir at room temperature for 30 minutes. After that, 52.1 g of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.) was added while stirring. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the aqueous silica sol was heated to 60° C. while refluxing, held at 60° C. for 4 hours, and then cooled. After cooling to room temperature, the aqueous sol was taken out.
The mass ratio of the silane compound to the silica solid content in the aqueous silica sol was 0.64, the silica solid content = 17.5 mass%, pH = 3.6, electrical conductivity = 903 µS / cm, DLS average particle size = 22.2 nm. 543.1 g of an aqueous sol containing an aqueous silica sol surface-treated with a silane compound (hereinafter referred to as an aqueous silica sol produced in Synthesis Example 1) was obtained.
When the amount of bonding of the silane compound (N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane) was calculated according to the silane compound bonding amount evaluation-1, 1.2 units were bonded per 1 nm ² of silica sol. .

(Synthesis example 2)
400 g of aqueous silica sol (Snowtex (registered trademark) ST-OXS manufactured by Nissan Chemical Industries, Ltd., silica solid content concentration = 10.4 mass%, Sears method average particle size 5.1 nm) and magnetic stirring in a 1 L glass eggplant flask. After adding the ingredients, 10.2 g of lactic acid (manufactured by Kanto Kagaku Co., Ltd., purity 92%) was added to the silica in the aqueous silica sol while stirring with a magnetic stirrer, and the mixture was stirred at room temperature for 30 minutes. After that, 5.9 g of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.) was added while stirring. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the aqueous silica sol was heated to 60° C. while refluxing, held at 60° C. for 4 hours, and then cooled. After cooling to room temperature, the aqueous sol was taken out.
The mass ratio of the silane compound to the silica solid content in the aqueous silica sol was 0.14, silica solid content = 10.4 mass%, pH = 3.7, electrical conductivity = 1140 µS / cm, DLS average particle size = 26.6 nm. 416.1 g of an aqueous sol containing an aqueous silica sol surface-treated with a silane compound (hereinafter referred to as an aqueous silica sol produced in Synthesis Example 2) was obtained.
When the amount of bonding of the silane compound (N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane) was calculated according to the evaluation of the bonding amount of silane compound, it was found to be 1.0 bonding per 1 nm ² of silica sol.

(Synthesis Example 3)
400 g of aqueous silica sol (Snowtex (registered trademark) ST-OL manufactured by Nissan Chemical Industries, Ltd., silica solid content concentration = 20.5 mass%, BET method average particle size 43 nm) and a magnetic stirrer were added to a 1 L glass eggplant flask. After the addition, 24.8 g of lactic acid (manufactured by Kanto Kagaku Co., Ltd., purity 92%) was added to the silica in the aqueous silica sol while stirring with a magnetic stirrer, and the mixture was stirred at room temperature for 30 minutes. After that, 14.2 g of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.) was added while stirring. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the aqueous silica sol was heated to 60° C. while refluxing, held at 60° C. for 4 hours, and then cooled. After cooling to room temperature, the aqueous sol was taken out.
The mass ratio of the silane compound to the silica solid content in the aqueous silica sol was 0.17, silica solid content = 19.8 mass%, pH = 3.7, electrical conductivity = 870 μS / cm, DLS average particle size = 26.6 nm. 439.1 g of an aqueous sol containing an aqueous silica sol surface-treated with a silane compound (hereinafter referred to as an aqueous silica sol produced in Synthesis Example 3) was obtained.
When the amount of bonding of the silane compound (N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane) was calculated according to the silane compound bonding amount evaluation-1, 1.0 bonding per 1 nm ² of silica sol was found. .

[Preparation of chemical solution for crude oil recovery]
(Example 1)
A stirrer was placed in a 120 mL styrene bottle, and 75.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 4.3 g of pure water while stirring with a magnetic stirrer, 0.4 g of a cationic surfactant hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) is added and completely dissolved. The chemical solution of Example 1 was produced by stirring to . At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 1 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 2)
Example 1, except that the amount of pure water added was 3.3 g, and 1.4 g of lauryltrimethylammonium chloride (Cathiogen (registered trademark) TML manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added as a cationic surfactant. The chemical liquid of Example 2 was produced by the same operation. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 2 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 3)
Example 1 except that the amount of pure water added was 3.3 g, and 1.3 g of cetyltrimethylammonium chloride (Cathiogen (registered trademark) TMP manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added as a cationic surfactant. The chemical solution of Example 3 was produced by the same operation. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 3 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 4)
The amount of pure water added was 3.9 g, and 0.8 g of lauryldimethylbenzylammonium chloride (Daiichi Kogyo Seiyaku Co., Ltd. Cathiogen (registered trademark) BC-50) was added as a cationic surfactant. The chemical solution of Example 4 was prepared in the same manner as in Example 1. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 4 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, the sample was taken out, and high-temperature salt resistance-1 was evaluated according to <Determination of Salt Tolerance>.

(Example 5)
The amount of pure water added was 3.9 g, and 0.8 g of lauryldimethylethylammonium ethyl sulfate (Daiichi Kogyo Seiyaku Co., Ltd. Cathiogen (registered trademark) ES-L) was added as a cationic surfactant. A chemical solution of Example 5 was produced in the same manner as in Example 1. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 5 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 6)
The amount of pure water added was 3.9 g, and 0.8 g of octyldimethylethylammonium ethylsulfate (Daiichi Kogyo Seiyaku Co., Ltd. Cathiogen (registered trademark) ES-O) was added as a cationic surfactant. A chemical solution of Example 6 was produced in the same manner as in Example 1. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 6 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 7)
Except that the amount of pure water added was 4.1 g, and 0.6 g of palmityldimethylethylammonium ethyl sulfate (Cathiogen (registered trademark) ES-P manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added as a cationic surfactant. , the chemical solution of Example 7 was produced in the same manner as in Example 1. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 7 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 8)
A stirrer was placed in a 100 mL eggplant flask, and 50.5 g of the aqueous silica sol produced in Synthesis Example 1 was added. 2.0 g of pure water was added while stirring with a magnetic stirrer. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the temperature of the aqueous sol was raised to 60°C while refluxing. , 99+%) was added and stirred until completely dissolved. Subsequently, as a nonionic surfactant, polyoxyethylene styrenated phenyl ether (Noigen (registered trademark) EA-157 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with HLB = 14.3 was diluted with pure water to obtain an active ingredient of 70%. After adding 0.9 g of the obtained mixture while stirring at 60° C., it was held at 60° C. for 1 hour to prepare a chemical solution of Example 8. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03, and the mass ratio of the nonionic surfactant to the silica solid content of the aqueous silica sol was 0.07. The pH and electrical conductivity of the chemical solution of Example 8 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 9)
Example 8 except that the amount of pure water added was 1.1 g, and 1.1 g of stearyltrimethylammonium chloride (Daiichi Kogyo Seiyaku Co., Ltd. Cathiogen (registered trademark) TMS) was added as a cationic surfactant. A chemical solution of Example 9 was prepared by the same operation. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 9 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 10)
A stirrer was placed in a 120 mL styrene bottle, and 28.2 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 1.4 g of pure water while stirring with a magnetic stirrer, 0.08 g of hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) as a cationic surfactant was added and completely dissolved. Stir until smooth. Subsequently, 0.27 g of betaine lauryldimethylaminoacetate (Amogen (registered trademark) SH manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was administered as an amphoteric surfactant to prepare a drug solution of Example 10. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.016, and the mass ratio of the amphoteric surfactant to the silica solid content of the aqueous silica sol was 0.016. The pH and electrical conductivity of the chemical solution of Example 10 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 11)
A stirrer was placed in a 120 mL styrene bottle, and 28.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 0.93 g of pure water while stirring with a magnetic stirrer, 0.08 g of hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) as a cationic surfactant was added and completely dissolved. Stir until smooth. Subsequently, 0.27 g of betaine lauryldimethylaminoacetate (Amogen (registered trademark) SH manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was administered as an amphoteric surfactant. After that, as a nonionic surfactant, polyoxyethylene styrenated phenyl ether (Noigen (registered trademark) EA-157 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with HLB = 14.3 is diluted with pure water to make the active ingredient 70%. 0.47 g of the obtained mixture was added and stirred at room temperature for 1 hour to prepare a chemical solution of Example 11. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.016, the mass ratio of the amphoteric surfactant to the silica solid content of the aqueous silica sol was 0.016, and the nonionic surfactant to the silica solid content of the aqueous silica sol was The surfactant mass ratio was 0.07. The pH and electrical conductivity of the chemical solution of Example 11 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 12)
Using the chemical solution prepared in Example 1, salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt tolerance at high salinity concentrations according to <Determination of Salt Tolerance>. .

(Example 13)
A stirrer was placed in a 120 mL styrene bottle, and 75.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 4.5 g of pure water while stirring with a magnetic stirrer, 0.2 g of a cationic surfactant hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) is added and completely dissolved. Stir until Subsequently, 0.7 g of lauryltrimethylammonium chloride (Cathiogen (registered trademark) TML manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added to prepare a chemical solution of Example 13. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 13 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 14)
A stirrer was placed in a 100 mL eggplant flask, and 75.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. 3.3 g of pure water was added while stirring with a magnetic stirrer. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the temperature of the aqueous sol was raised to 60°C while refluxing. , 99+%) was added and stirred until completely dissolved. Subsequently, 0.9 g of polyoxyalkylenealkylamine (Puremeal (registered trademark) CF-60 manufactured by Sanyo Kasei Co., Ltd.) as a nonionic surfactant with HLB = 13.6 was added while stirring at 60 ° C., A chemical solution of Example 14 was produced by holding at 60° C. for 1 hour. At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03, and the mass ratio of the nonionic surfactant to the silica solid content of the aqueous silica sol was 0.07. The pH and electrical conductivity of the chemical solution of Example 14 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 15)
A stirrer was placed in a 120 mL styrene bottle, and 77.2 g of the aqueous silica sol produced in Synthesis Example 2 was added. After adding 2.4 g of pure water while stirring with a magnetic stirrer, 0.4 g of a cationic surfactant hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) is added and completely dissolved. The chemical solution of Example 15 was produced by stirring to . At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.05. The pH and electrical conductivity of the chemical solution of Example 15 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Example 16)
A stirrer was placed in a 120 mL styrene bottle, and 76.9 g of the aqueous silica sol produced in Synthesis Example 3 was added. After adding 2.7 g of pure water while stirring with a magnetic stirrer, 0.4 g of a cationic surfactant hexadecyltrimethylammonium bromide (Hexadecyltrimethylammonium bromide, 99+%, manufactured by ACROS ORGANICS Co., Ltd.) is added and completely dissolved. The chemical solution of Example 16 was produced by stirring to . At this time, the mass ratio of the cationic surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH and electrical conductivity of the chemical solution of Example 16 and the DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution were evaluated.
A salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt resistance at high salinity concentrations according to <Determination of Salt Tolerance>.

(Example 17)
Using the chemical solution prepared in Example 13, salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt tolerance at high salinity concentrations according to <Determination of Salt Tolerance>. .

(Example 18)
Using the chemical solution prepared in Example 14, a salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt tolerance at high salinity concentrations according to <Determination of Salt Tolerance>. .

(Example 19)
Using the chemical solution prepared in Example 15, a salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt tolerance at high salinity concentrations according to <Determination of Salt Tolerance>. .

(Synthesis Example 4)
Aqueous silica sol (Snowtex (registered trademark) ST-O manufactured by Nissan Chemical Industries, Ltd., silica concentration = 20.5% by mass, BET method average particle size 11.0 nm, DLS average particle size 17.0 nm) was added to a 500 mL glass eggplant flask. 2 nm) and a magnetic stirrer, and then 3-glycidoxypropyltrimethoxysilane (3-glycidoxypropyltrimethoxysilane ( 31.8 g of Dynasylan GLYMO manufactured by Evonik was added. Subsequently, a cooling pipe through which tap water was run was installed at the top of the eggplant flask, and the temperature of the aqueous sol was raised to 60° C. while refluxing, held at 60° C. for 3 hours, and then cooled. After cooling to room temperature, the aqueous sol was taken out.
Silane with a mass ratio of silane compound to silica in the aqueous sol of 0.16, silica solid content = 21.0 mass%, pH = 2.7, electrical conductivity = 415 μS / cm, DLS average particle size = 21.5 nm 248.6 g of an aqueous sol containing an aqueous silica sol surface-treated with a compound (hereinafter referred to as an aqueous silica sol produced in Synthesis Example 4) was obtained.
When the bonding amount of the silane compound (3-glycidoxypropyltrimethoxysilane) was calculated according to the silane compound bonding amount evaluation- ² , 1.5 bonding per 1 nm 2 of silica sol was found.

(Comparative example 1)
A stirrer was placed in a 120 mL styrene bottle, and 101.0 g of the aqueous silica sol produced in Synthesis Example 4 was added while stirring with a magnetic stirrer. After adding 15 g of pure water, 0.96 g of anionic surfactant sodium α-olefin sulfonate (Neogen (registered trademark) AO-90 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added and stirred until completely dissolved. . Subsequently, 0.36 of an anionic surfactant sodium dodecyl sulfate (Shinoline (registered trademark) 90TK-T, manufactured by Shin Nippon Rika Co., Ltd.) was added and stirred until completely dissolved. Subsequently, as a nonionic surfactant, polyoxyethylene styrenated phenyl ether (Noigen (registered trademark) EA-157 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with HLB = 14.3 was diluted with pure water to obtain an active ingredient of 70%. 2.07 g of the resulting mixture was added to prepare a chemical solution of Comparative Example 2. At this time, the mass ratio of the anionic surfactant to the silica solid content of the aqueous silica sol was 0.03, and the mass ratio of the nonionic surfactant to the silica solid content of the aqueous silica sol was 0.07. The pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution of Comparative Example 1 were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Comparative example 2)
A stirrer was placed in a 120 mL styrene bottle, and 75.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 3.2 g of pure water while stirring with a magnetic stirrer, amphoteric surfactant betaine lauryldimethylaminoacetate (Amogen (registered trademark) SH, active ingredient 30%, Daiichi Kogyo Seiyaku Co., Ltd.). 1.4 g was added and stirred until completely dissolved to prepare a chemical solution of Comparative Example 2. At this time, the mass ratio of the amphoteric surfactant to the silica solid content of the aqueous silica sol was 0.03. The pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution of Comparative Example 2 were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Comparative Example 3)
A stirrer was placed in a 120 mL styrene bottle, and 75.3 g of the aqueous silica sol produced in Synthesis Example 1 was added. After adding 2.0 g of pure water while stirring with a magnetic stirrer, amphoteric surfactant betaine lauryldimethylaminoacetate (Amogen (registered trademark) SH, active ingredient 30%, Daiichi Kogyo Seiyaku Co., Ltd.). 1.4 g was added and stirred until completely dissolved. After that, as a nonionic surfactant, polyoxyethylene styrenated phenyl ether (Noigen (registered trademark) EA-157 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with HLB = 14.3 is diluted with pure water to make the active ingredient 70%. 1.3 g of the resulting mixture was added and stirred at room temperature for 1 hour to prepare a chemical solution of Comparative Example 3. At this time, the mass ratio of the amphoteric surfactant to the silica solid content of the aqueous silica sol was 0.03, and the mass ratio of the nonionic surfactant to the silica solid content of the aqueous silica sol was 0.07. The pH, electrical conductivity, and DLS average particle size of the aqueous silica sol (silica particles) in the chemical solution of Comparative Example 3 were evaluated.
A salt water test sample 1 was prepared according to Salt Tolerance Evaluation-1, held at 120° C. for 60 hours, then taken out and evaluated for high temperature salt resistance according to <Determination of Salt Tolerance>.

(Comparative Example 4)
Using the chemical solution prepared in Comparative Example 1, a salt water test sample 2 was prepared according to Salt Tolerance Evaluation-2, allowed to stand at room temperature for 7 days, and then evaluated for salt tolerance at high salinity concentrations according to <Determination of Salt Tolerance>. .

Table 1 (Tables 1-1, 1-2, and 1-3) shows physical properties of chemical solutions and salt resistance evaluation samples (salt water test samples) and salt resistance test results of Examples and Comparative Examples.
The types (codes) of cationic surfactants, amphoteric surfactants and nonionic surfactants in the table are as follows.
<Cationic surfactant>
・CTAB: Hexadecyltrimethylammonium bromide "Hexadecyltrimethylammonium bromide, 99+%", active ingredient 99% or more, ACROS ORGANICS Co., Ltd.
・ LTAC: Lauryltrimethylammonium chloride “Cathiogen (registered trademark) TML”, active ingredient 30.0%, Daiichi Kogyo Seiyaku Co., Ltd.
・RTMAC1: cetyltrimethylammonium chloride “Cathiogen (registered trademark) TMP”, active ingredient 30%, Daiichi Kogyo Seiyaku Co., Ltd.
・RTMAC2: Stearyltrimethylammonium chloride “Cathiogen (registered trademark) TMS”, active ingredient 25%, Daiichi Kogyo Seiyaku Co., Ltd.
・RDMBnAC: Lauryldimethylbenzylammonium chloride “Cathiogen (registered trademark) BC-50”, active ingredient 50%, Daiichi Kogyo Seiyaku Co., Ltd.
・ RDMEAS1: Lauryl dimethylethyl ammonium ethyl sulfate “Cathiogen (registered trademark) ES-L”, active ingredient 50%, Daiichi Kogyo Seiyaku Co., Ltd.
・ ODMEAS: Octyldimethylethylammonium ethylsulfate “Cathiogen (registered trademark) ES-O”, active ingredient 50%, Daiichi Kogyo Seiyaku Co., Ltd.
・ RDMEAS2: Palmityldimethylethylammonium ethylsulfate “Cathiogen (registered trademark) ES-P”, active ingredient 70%, Daiichi Kogyo Seiyaku Co., Ltd.
<Anionic surfactant>
・ AOS: sodium α-olefin sulfonate “Neogen (registered trademark) AO-90”, active ingredient 36.3%, Daiichi Kogyo Seiyaku Co., Ltd.
・ SDS: Sodium dodecyl sulfate “Shinoline (registered trademark) 90TK-T”, active ingredient 96.0%, New Japan Chemical Co., Ltd.
<Amphoteric Surfactant>
・RDMAAcB: Lauryldimethylaminoacetic acid betaine “Amogen (registered trademark) SH”, active ingredient 30%, Daiichi Kogyo Seiyaku Co., Ltd.
<Nonionic surfactant>
・ EA-157: Polyoxyethylene styrenated phenyl ether "Noigen (registered trademark) EA-157", 100% active ingredient, Daiichi Kogyo Seiyaku Co., Ltd.
・ PM-CF60: Polyoxyalkylene alkylamine “Puremeal (registered trademark) CF-60”, 100% active ingredient, Sanyo Kasei Co., Ltd.

[Evaluation of crude oil recoverability-1]
Using the crude oil recovery chemicals of Examples 1, 9, and Comparative Example 1, and using crude oil and Berea sandstone, crude oil recovery evaluation was performed assuming an underground oil layer.
The chemical solution for crude oil recovery was adjusted to have a silica concentration of 0.5% by mass with salt water having a salt concentration of 4% by mass, and this was used as a sample for evaluating crude oil recovery performance.
Medium Sour Russian Urals REBCO Crude Oil purchased from ONTA was used as the crude oil.
Berea sandstone samples dried at 60° C. for 1 day were used with a permeability of about 100 mD, a pore volume of about 5 mL, a length of 2 inches and a diameter of 1 inch.

A Berea sandstone sample is immersed in a salt water solution with a salt concentration of 4% by mass in a vacuum container, and the pressure inside the container is reduced using a vacuum pump to saturate the Berea sandstone sample with the salt water. to obtain the salt water saturation rate. The salt water saturation rate was calculated based on the following formula. The salt water specific gravity is 1.028 g/cm ³ .

A Berea sandstone sample saturated with salt water was set in a core holder of a sweep method oil recovery device SRP-350 (manufactured by Vinci). After raising the temperature of the core holder to 50°C, crude oil was injected into the Berea sandstone sample while applying a lateral pressure of 800 psi to the Berea sandstone sample using a hydraulic pump, and then the Berea sandstone sample was removed from the core holder and transferred to a pressure bottle. . After that, the pressure bottle containing the Berea sandstone sample was filled with crude oil and allowed to stand at 50° C. for 60 days to obtain an aged sample. The oil saturation of the aged samples was determined gravimetrically. The oil saturation rate was calculated based on the following formula. Crude oil has a specific gravity of 0.878 g/cm ³ .

After setting the oil-saturated Berea sandstone sample again in the core holder of the sweep method oil recovery device SRP-350, salt water with a salt concentration of 4% by mass was injected into the Berea sandstone sample at a flow rate of 0.2 mL / min and discharged. The volume of crude oil was used to determine the salt-swept oil recovery rate.
Subsequently, the crude oil recovery performance evaluation sample of the example or comparative example prepared as described above was injected into the Berea sandstone sample at a flow rate of 0.2 mL / min, and the volume of discharged crude oil was chemically swept to recover oil. asked for a rate.
Table 2 shows the oil recovery rate results of Examples and Comparative Examples.

As shown in Table 1 (Tables 1-1, 1-2, and 1-3), the chemical solutions of Examples 1 to 11 and 13 to 15 were all heated in salt water at 120°C for a long time. No layer separation or gelation was observed afterward. Also, regarding the DLS average particle size of the aqueous silica sol (silica particles) in the sample, the ratio of the DLS average particle size after the salt resistance test to the DLS average particle size of the chemical solution is 1.5 or less, and the silica sol is not deteriorated. It was confirmed that the chemical solution is stable and has excellent high-temperature salt resistance.

On the other hand, an anionic silane compound is used instead of a cationic silane compound as the silane compound, and AOS and SDS, which are anionic surfactants, and EA, which is a nonionic surfactant, are used instead of cationic surfactants as surfactants. Comparative Example 1 using -157, a cationic silane compound as the silane compound, Comparative Example 2 using only the amphoteric surfactant RDMMAcB, the amphoteric surfactant RDMMAcB and the nonionic surfactant In Comparative Example 3 using a certain EA-157, a large amount of white gel was formed in the high-temperature salt resistance evaluation, and the high-temperature salt resistance was very poor.

In addition, Example 12 (chemical solution prepared in Example 1) in Table 1 (Table 1-2), Example 16 in Table 1-3, Example 17 (chemical solution prepared in Example 13), Example 18 ( As shown in Example 14 (chemical solution prepared in Example 14) and Example 19 (chemical solution prepared in Example 15), the chemical solution used in this example was kept in salt water with a salt concentration of 17% by mass for a long time. No layer separation or gelation was observed. Also, regarding the DLS average particle size of the aqueous silica sol (silica particles) in the sample, the ratio of the DLS average particle size after the salt resistance test to the DLS average particle size of the chemical solution is 1.5 or less, and the silica sol is not deteriorated. It was confirmed from this example that the chemical solution is stable and has excellent salt resistance at high salt concentrations.

On the other hand, an anionic silane compound is used instead of a cationic silane compound as the silane compound, and AOS and SDS, which are anionic surfactants, and EA, which is a nonionic surfactant, are used instead of cationic surfactants as surfactants. In Comparative Example 4 using -157 (chemical solution prepared in Comparative Example 1), a large amount of white gel was formed in the salt tolerance evaluation, and the salt tolerance at high salinity concentrations was very poor.

In addition, as shown in Table 2, the chemical solutions of Examples 1 and 9 were found to have an oil-increasing effect after saltwater sweeping with respect to the oil recovery rate of the chemical solution (oil recovery rate of chemical solution sweeping). It should be noted that although the chemical solutions of Examples show results equivalent to or lower than those of Comparative Example 1 in terms of the oil recovery rate of the chemical solution (oil recovery rate of chemical sweeping), the chemical solutions of Examples according to the present invention are high-temperature and It is a chemical solution that aims to improve salt resistance to high salinity concentrations (see Table 1 (Tables 1-1 to 1-3)), and is extremely excellent in that it achieves both salt resistance and improved oil recovery rate. It can be called a chemical solution.

From the above results, the crude oil recovery chemical solution of the present invention has excellent high-temperature salt resistance at high temperatures exceeding 100 ° C. and / or salt resistance at high salinity concentrations exceeding 10 mass%, and has a high oil-increasing effect. It was confirmed that it is a high-performance crude oil recovery chemical.

Claims

A chemical liquid for crude oil recovery, comprising a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants.
2. The chemical liquid for crude oil recovery according to claim 1, wherein the aqueous silica sol contains silica particles in which at least a portion of the cationic silane compound is bonded to at least a portion of the surface of the silica particles in the sol.
The cationic silane compound is at least one compound selected from the group consisting of a silane coupling agent having an amino group, an alkoxysilane having an amino group, a silazane having an amino group, and a siloxane having an amino group. The chemical solution for crude oil recovery according to claim 1 or 2.
4. The crude oil recovery chemical solution according to any one of claims 1 to 3, further comprising an amphoteric surfactant.
5. The crude oil recovery chemical solution according to any one of claims 1 to 4, further comprising a nonionic surfactant.
Any one of claims 1 to 5, wherein the aqueous silica sol is contained in an amount of 0.01% by mass to 50% by mass based on the total mass of the crude oil recovery chemical in terms of silica solid content. 1. The chemical solution for crude oil recovery according to item 1.
The crude oil according to any one of claims 1 to 6, wherein the silane compound is contained at a mass ratio of 0.001 to 10.0 with respect to the silica solid content of the aqueous silica sol. Recovery chemical.
wherein said cationic surfactant is selected from the group consisting of alkylamine salts, quaternary ammonium salts, and alkylpyridinium salts;
The chemical liquid for crude oil recovery according to any one of claims 1 to 7.
9. Any one of claims 1 to 8, wherein the cationic surfactant is contained at a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. The chemical liquid for crude oil recovery described in the paragraph.
The amphoteric surfactant for crude oil recovery according to any one of claims 4 to 9, wherein the amphoteric surfactant is selected from the group consisting of carboxybetaine salt, 2-alkylimidazoline derivative type, glycine type and amine oxide type. chemical solution.
Any one of claims 4 to 10, wherein the amphoteric surfactant is contained at a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. Chemicals for crude oil recovery.
The nonionic surfactant has an HLB value of 3.0 or more and 20.0 or less, and
from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyalkylene alkylamines, alkyl glucosides, polyoxyethylene fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters and fatty acid alkanolamides To be elected,
The chemical solution for crude oil recovery according to any one of claims 5 to 11.
Any one of claims 5 to 12, wherein the nonionic surfactant is contained at a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content of the crude oil recovery chemical. 1. The chemical solution for crude oil recovery according to item 1.
A method of recovering crude oil from underground hydrocarbon-bearing formations comprising:
(a) a step of forcing a crude oil recovery chemical containing a cationic silane compound, an aqueous silica sol having an average particle size of 3 to 500 nm, and one or more cationic surfactants into an underground layer;
(b) recovering the crude oil from the production well together with the chemical injected into the underground layer;
method including.
15. The chemical liquid for crude oil recovery, wherein the cationic surfactant is contained in the chemical liquid for crude oil recovery in a mass ratio of 0.001 or more and less than 0.4 with respect to the silica solid content thereof. The method described in .
16. The method of claim 14 or 15, wherein the crude oil recovery chemical further contains an amphoteric surfactant.
17. The method of any one of claims 14-16, wherein the crude oil recovery chemical further comprises a non-ionic surfactant.