JP6179470B2 - Underground treatment composition - Google Patents

Description

  The present invention relates to a composition for treating an underground layer having high salt resistance and excellent water stopping properties.

  Natural resources such as gas, oil, and water that are present in the underground layer or area are usually recovered by drilling the drilling hole to the underground layer while circulating the drilling fluid through the drilling hole. For oil and gas recovery, fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid ), Stimulation fluid, sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid ), Drilling fluids, frac-packing fluids, water conformance fluids, or gravel packing fluids, etc. Is done.

  Additives such as anti-mudging agents, specific gravity agents, dispersants, surfactants, viscosity modifiers, thickeners, etc. are added to the underground layer treatment fluid. For bentonite, mica, slaked lime, and carbosi for the purpose of reducing friction, cooling bits, carrying out crushed rocks, preventing water and mud during excavation, and preventing collapsing of pit walls It is prepared by dispersing xymethyl cellulose, silicone resin, etc. in a liquid carrier such as water or an organic solvent.

  When clay minerals are contained in the stratum to be excavated, problems such as swelling and collapse occur in response to water in the well treatment fluid. Therefore, there is a prescription in which a large amount of salt is added to the well treatment fluid in order to suppress hydration swelling of the clay mineral. In addition, in a place where fresh water is difficult to obtain, a dispersion solvent having a high salt concentration such as seawater is used, and salt resistance is required for additives for well treatment fluids. In addition, the cementing fluid contains a large amount of calcium ions derived from the cement component.

  On the other hand, fine cellulose fibers (Patent Document 1) and cellulose nanowhiskers (Patent Document 2) produced by an acid hydrolysis method are known as components of the thickener in such applications. Moreover, the composition for the underground layer process containing nanocrystalline cellulose is proposed (patent document 3). Furthermore, in recent years, an innovative method for producing nano-sized fine cellulose fibers while maintaining the crystallinity of cellulose has been developed (Non-patent Document 1). In this method, after introducing an aldehyde group or a carboxyl group to the surface of the cellulose fiber, fine cellulose fiber is generated by mechanical treatment. In addition to high crystallinity, fine cellulose fibers obtained by this method can be obtained as long fibers as compared to cellulose nanowhiskers, and can be a highly viscous gel in water. It has been proposed to use fine cellulose fibers produced by this method as a thickener for cosmetics or a thickener for excavation (Patent Documents 4 and 5).

US Pat. No. 6,348,436 US2013 / 0196883 US2013 / 0274149 JP 2010-37348 A (Patent No. 5296445) US2013 / 0035263

Saito T & al.Homogeneous suspentions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose.Biomacromolecules 2006, 7 (6), 1687-91

However, the surface of the fine cellulose fiber described above is anionized and easily reacts with cations present in the salt water to cause aggregation. As a result, effects such as thickening and water stopping properties are not sufficient. In addition, fine cellulose fibers not subjected to surface modification are not sufficiently refined, and as a result, the viscosity increase is insufficient.
An object of the present invention is to provide a composition for treating an underground layer having high salt resistance and excellent water-stopping property.

  The present inventors diligently studied to solve the above problems. As a result, it has been found that by blending cation-modified fine fiber cellulose into a fluid as a composition for treating an underground layer, it maintains a high viscosity in the presence of salt and exhibits excellent water-stopping properties. It came to complete.

That is, according to the present invention, the following inventions are provided.
[1] A composition for treating an underground layer containing fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g.
[2] The composition according to 1, wherein the fiber width of the fine cellulose fibers is 200 nm or less.
[3] The composition according to 1 or 2 for use by adding to an alkaline underground fluid.
[4] The composition according to any one of 1 to 3, which has salt resistance.
[5] The composition according to any one of 1 to 4, which has a water-stopping property.
[6] Fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid, stimulation fluid (Stimulation fluid), sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid, drilling fluid 1 to 5 for use in addition to (drilling fluid), frac-packing fluid, water conformance fluid, or gravel packing fluid The composition according to item.
[7] A fluid for underground layer treatment, comprising the composition according to any one of 1 to 6, wherein the solid content concentration of the cellulose fiber is 0.05 to 2% by mass.
[8] The composition according to any one of 1 to 6, and a weighting agent, a viscosity modifier, a dispersant, a flocculant, a mud prevention agent, a pH control agent, a friction reducing agent, a hydration expansion controlling agent, Including any selected from the group consisting of emulsifiers, surfactants, biocides, antifoams, scale inhibitors, corrosion inhibitors, temperature stabilizers, resin coating agents, crack supports, salts, and proppants, Fluid for underground layer treatment.
[9] A fluid for treating an underground layer, comprising the composition according to any one of 1 to 6 and an anionic additive.
[10] The underground layer treatment fluid according to 9, wherein the anionic additive is a mineral.
[11] The fluid according to any one of 7 to 10, which is a fracturing fluid, mud water, or a cementing fluid.
[12] A method for treating an underground layer using the composition according to any one of 1 to 6 or the fluid according to any one of 7 to 11.
[13] A method for producing petroleum resources, wherein the composition according to any one of 1 to 6 or the fluid according to any one of 7 to 11 is used.
[14] A method for producing an underground layer treatment fluid, comprising adding an aqueous dispersion of fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g to the fluid.
[15] The method according to any one of 1 to 7, comprising a step of concentrating or drying a dispersion of fine cellulose fibers and redispersing the obtained concentrated solution or dried product in an aqueous solvent to obtain a redispersion. A method for producing the composition described.
[16] The production method according to 15, wherein the concentration is performed by a concentration agent and / or a dryer.

The present invention also provides the following.
[1] Use of a composition containing fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g in the treatment of an underground layer.
[2] The use according to 1, wherein the fine cellulose fiber has a fiber width of 200 nm or less.
[3] The use according to 1 or 2, wherein the composition is used by adding it to an alkaline underground fluid.
[4] The use according to any one of 1 to 3, wherein the composition has salt resistance.
[5] The use according to any one of 1 to 4, wherein the composition has a water-stopping property.
[6] The composition is divided into fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid. ), Stimulation fluid, sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid ), Drilling fluid, frac-packing fluid, water conformance fluid, or gravel packing fluid, any of 1-5 Or use according to item 1.
[7] Use of the composition defined in any one of 1 to 6 in an underground layer treatment fluid, wherein a solid content concentration of cellulose fibers in the fluid is 0.05 to 2% by mass. use.
[8] A weighting material, a viscosity modifier, a dispersant, a flocculant, an anti-mudging agent, a pH control agent, a friction reducing agent, a hydration expansion control agent of the composition defined in any one of 1 to 6 Any one selected from the group consisting of an emulsifier, a surfactant, a biocide, an antifoaming agent, a scale inhibitor, a corrosion inhibitor, a temperature stabilizer, a resin coating agent, a crack support material, a salt, and a proppant. Use in subsurface fluids.
[9] Use of the composition defined in any one of 1 to 6 and an anionic additive in a fluid for underground layer treatment.
[10] The use according to 9, wherein the anionic additive is a mineral.
[11] The use according to any one of 7 to 9, wherein the fluid is a fracturing fluid, a muddy water, or a cementing fluid.

The present invention further provides the following.
[1] A method for treating an underground layer, wherein the underground layer is treated with a composition containing fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g.
[2] The method according to 1, wherein the fine cellulose fiber has a fiber width of 200 nm or less.
[3] The method according to 1 or 2, wherein the composition is used after being added to an alkaline underground fluid.
[4] The method according to any one of 1 to 3, wherein the composition has salt resistance.
[5] The method according to any one of 1 to 4, wherein the composition has a water-stopping property.
[6] The composition is divided into fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid. ), Stimulation fluid, sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid ), Drilling fluid, frac-packing fluid, water conformance fluid, or gravel packing fluid, any of 1-5 The method according to claim 1.
[7] A method for treating an underground layer, comprising the composition defined in any one of 1 to 6 and treating the underground layer with a fluid having a solid content concentration of cellulose fibers of 0.05 to 2% by mass. .
[8] The composition according to any one of 1 to 6, and a weighting agent, a viscosity modifier, a dispersant, a flocculant, a mud prevention agent, a pH control agent, a friction reducing agent, a hydration expansion controlling agent, Fluid containing any one selected from the group consisting of emulsifiers, surfactants, biocides, antifoams, scale inhibitors, corrosion inhibitors, temperature stabilizers, resin coating agents, crack supports, salts, and proppants In the underground layer processing method.
[9] A method for treating an underground layer, wherein the underground layer is treated with a fluid containing the composition defined in any one of 1 to 6 and an anionic additive.
[10] The method for treating an underground layer according to 9, wherein the anionic additive is a mineral.
[11] The method according to any one of 7 to 10, wherein the fluid is a fracturing fluid, a muddy water, or a cementing fluid.

  According to the present invention, a composition for treating an underground layer having high salt resistance and excellent water-stopping properties is provided.

Hereinafter, the present invention will be described in more detail. Note that the descriptions of materials, methods, numerical ranges, and the like described in this specification are only examples of embodiments of the invention, and are intended to limit the scope of the invention to the materials, methods, numerical ranges, and the like. It is not a thing. Nor does it exclude the use of other materials, methods and numerical ranges.
The range “X to Y” includes both end values. “%” Represents a ratio based on mass, unless otherwise specified.

[Fine cellulose fiber-containing composition]
In this invention, the fine cellulose fiber which has a cationic group obtained by carrying out the chemical process and the fibrillation process of a cellulose raw material can be used.

<Fine cellulose fiber>
Examples of cellulose raw materials include paper pulp, cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw, and bagasse, cellulose isolated from sea squirts and seaweed, etc., but are not particularly limited. . Among these, paper pulp is preferable in terms of availability, but is not particularly limited. Paper pulp includes hardwood kraft pulp (bleached kraft pulp (LBKP), unbleached kraft pulp (LUKP), oxygen bleached kraft pulp (LOKP), etc.), softwood kraft pulp (bleached kraft pulp (NBKP), unbleached kraft pulp) (NUKP), oxygen bleached kraft pulp (NOKP), etc.). Also, chemical pulp such as sulfite pulp (SP) and soda pulp (AP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), groundwood pulp (GP), thermomechanical pulp (TMP) , BCTMP), etc., non-wood pulp made from cocoons, cocoons, hemp, kenaf, etc., and deinked pulp made from waste paper, but are not particularly limited. Among these, kraft pulp, deinked pulp, and sulfite pulp are preferable because they are more easily available, but are not particularly limited. A cellulose raw material may be used individually by 1 type, and may be used in mixture of 2 or more types.

  In the present invention, the term “cellulose fiber” includes coarse cellulose fibers and fine cellulose fibers unless otherwise specified.

  The average fiber width of coarse cellulose fibers (sometimes simply referred to as coarse fibers) is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, as observed with an electron microscope.

  The average fiber width of fine cellulose fibers (sometimes simply referred to as fine fibers) is preferably 2 to 1000 nm, more preferably 2 to 100 nm, and more preferably 2 to 50 nm, as observed with an electron microscope. More preferably, it is 2 nm or more and less than 10 nm, but is not particularly limited. When the average fiber width of the fine cellulose fiber is less than 2 nm, the physical properties (strength, rigidity, dimensional stability) as the fine cellulose fiber are not exhibited because the cellulose molecule is dissolved in water. Here, it can be identified in the diffraction profile obtained from the wide angle X-ray diffraction photograph using CuKα (λ = 1.5418４) monochromatized with graphite that the fine cellulose fiber has the I-type crystal structure. Specifically, it can be identified by having typical peaks at two positions near 2θ = 14-17 ° and 2θ = 22-23 °.

  Measurement of the fiber width of the cellulose fiber by electron microscope observation is performed as follows. An aqueous suspension of cellulose fibers having a concentration of 0.05 to 0.1% by mass is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to obtain a sample for TEM observation. When a wide fiber is included, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50000 times depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.

(1) One straight line X is drawn at an arbitrary location in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.

  The width of the fiber that intersects with the straight line X and the straight line Y is visually read from the observation image that satisfies the above conditions. In this way, at least three sets of images of the surface portion that do not overlap each other are observed, and the width of the fiber intersecting with the straight line X and the straight line Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read. The average fiber width of cellulose fibers (sometimes simply referred to as “fiber width”) is an average value of the fiber widths read in this way.

  Although the fiber length of a fine cellulose fiber is not specifically limited, 1-1000 micrometers is preferable, 5-800 micrometers is more preferable, and 10-600 micrometers is especially preferable. When the fiber length is less than 1 μm, it is difficult to form a fine fiber sheet. If it exceeds 1000 μm, the slurry viscosity of the fine fibers becomes very high and it becomes difficult to handle. The fiber length can be obtained by image analysis using TEM, SEM, or AFM.

<Chemical treatment>
The method of chemical treatment of the cellulose raw material is not particularly limited as long as it is a method capable of obtaining fine fibers. Examples thereof include, but are not limited to, treatment with a compound capable of forming a covalent bond with a functional group in cellulose or a fiber raw material.

  The treatment with a compound having a quaternary ammonium group described in JP 2011-162608 A is a method of reacting a hydroxyl group in a fiber with a cationizing agent having a quaternary ammonium group to cation-modify the fiber. It is.

  The solid content concentration of the pulp subjected to the cationization reaction step is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass. If the solid content concentration of the pulp is within the above range, the reaction efficiency between the cellulose and the cationizing agent is increased, and fine cellulose fibers can be produced at a lower cost. When the pulp solid content concentration is less than the lower limit, it is difficult to set the solid content concentration of the pulp during the cationization reaction described later to a predetermined value or more.

Although an example of the method of manufacturing a cationized fine cellulose fiber is described below, the method of cationization is not limited to the following.
(Cationization reaction process)
The cationization reaction step in the present embodiment is a step of obtaining a cationized pulp by adding a cationizing agent and an alkali compound to the pulp and reacting them. Specifically, a cationized pulp is obtained by reacting a cationizing agent with a hydroxy group of cellulose contained in the pulp in the presence of an alkali compound.

As the cationizing agent, one having a quaternary ammonium group and a group that reacts with a hydroxy group of cellulose can be used. Examples of the group that reacts with the hydroxy group of cellulose include an epoxy group, a functional group having a halohydrin structure, a vinyl group, and a halogen group.
Specific examples of the cationizing agent include glycidyltrialkylammonium halides such as glycidyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride or halohydrin type compounds thereof.

  The addition amount of the cationizing agent is not particularly limited, but the addition amount of the cationizing agent per 1 g of the pulp dry mass is preferably 0.3 to 10 mmol, and preferably 0.9 to 4.8 mmol. More preferably, it is 1.6-3.0 mmol. If the addition amount of the cationizing agent is not less than the lower limit, the yield of fine cellulose fibers can be further increased. However, when the upper limit is exceeded, it becomes difficult to make the solid content concentration of the pulp during the cationization reaction equal to or higher than a predetermined value. In addition, the cost of the cationizing agent increases.

  The alkali compound used in the cationization step contributes to the promotion of the cationization reaction. The alkali compound may be an inorganic alkali compound or an organic alkali compound.

Examples of inorganic alkali compounds include alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal carbonates or alkaline earth metal carbonates, alkali metal phosphates or alkaline earth metal phosphoric acids. Salt.
Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, and potassium hydroxide. Examples of the alkaline earth metal hydroxide include calcium hydroxide.
Examples of the alkali metal carbonate include lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, and sodium hydrogen carbonate. Examples of the alkaline earth metal carbonate include calcium carbonate.
Examples of the alkali metal phosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of alkaline earth metal phosphates include calcium phosphate and calcium hydrogen phosphate.

Examples of the organic alkali compounds include ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates, and phosphates. For example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, Tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4-aminopyridine, ammonium carbonate, ammonium hydrogen carbonate, diammonium hydrogen phosphate, etc. Can be mentioned.
The said alkali compound may be single 1 type, and may combine 2 or more types.

Among the above alkali compounds, sodium hydroxide and potassium hydroxide are preferable because the cationization reaction is more likely to occur and the cost is low.
Although the quantity of an alkali compound changes according to the kind of alkali compound, it shall be in the range of 1-10 mass% with respect to a pulp absolute dry mass, for example.

  Since the cationizing agent and the alkali compound can be easily added to the pulp, it is preferable to form a solution. The solvent used for the solution may be either water or an organic solvent, but a polar solvent (polar organic solvent such as water or alcohol) is preferable, and an aqueous solvent containing at least water is more preferable.

In this production method, it is preferable that the solvent substance amount per 1 g of the pulp dry mass at the start of the cationization reaction is 5 to 150 mmol. The substance amount of the solvent is more preferably 5 to 80 mmol, and further preferably 5 to 60 mmol. When the amount of the solvent substance per 1 g of pulp dry mass at the start of the cationization reaction is higher than the upper limit, the reaction between the cationizing agent and a solvent such as water competes with the reaction between the cationizing agent and cellulose. The reaction efficiency is reduced, and the yield of fine cellulose fibers is reduced. On the other hand, when the amount of the solvent substance per 1 g of the pulp dry mass at the start of the cationization reaction is less than the lower limit, the cationizing agent does not easily penetrate into the pulp, and the cationization reaction hardly occurs.
In order to set the solid content concentration of the pulp during the cationization reaction within the above range, for example, a pulp having a high solid content concentration (that is, low moisture content) may be used. Moreover, it is preferable to reduce the amount of solvent contained in the solution of the cationizing agent and the alkali compound.

The reaction temperature in the cationization step is preferably in the range of 20 to 200 ° C, more preferably in the range of 40 to 100 ° C. If the reaction temperature is not less than the lower limit, sufficient reactivity can be obtained, and if the reaction temperature is not more than the upper limit, the reaction can be easily controlled. In addition, there is an effect of suppressing coloring of the pulp after the reaction.
The time for the cationization reaction varies depending on the type of pulp and cationizing agent, the pulp solid content concentration, the reaction temperature, etc., but is usually in the range of 0.5 to 3 hours.

  The cationization reaction may be performed in a closed system or an open system. Further, the solvent may be evaporated during the reaction, and the amount of the solvent substance per 1 g of the pulp dry mass at the end of the reaction may be lower than that at the start of the reaction.

<Washing process>
The washing step is a step of washing the cationized pulp to remove the remaining cationizing agent, alkali compound, and pulp decomposition products.
Specifically, in the washing step, various washing machines usually used for washing pulp, for example, a filter washing machine, a drum washing machine, a belt washing machine, a diffuser washing machine, a filter press, a screw press, and the like may be used. it can. Among these, a press washer such as a filter press or a screw press is preferable because of excellent dewaterability after washing.

<Acid addition process>
The acid addition step is a step of adding an acid to the cationized pulp washed in the washing step. When it has an acid addition process, the defibration property in a refinement | miniaturization process becomes higher, and the yield of a fine cellulose fiber becomes higher.
The acid added to the cationized pulp may be an inorganic acid or an organic acid. Specific examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid, hydrofluoric acid, boric acid and the like.
Specific examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, benzoic acid, oxalic acid, malonic acid, succinic acid, maleic acid, carboxylic acid such as citric acid, and methanesulfonic acid, Examples thereof include sulfonic acids such as benzenesulfonic acid and tosylic acid. It is preferable to make pH of a cationized pulp into 1-9 by an acid addition process, and it is more preferable to set it as 3-5. When the pH is set to the upper limit value or less, the effect of improving the defibration effect by adding an acid can be further improved. Moreover, when pH is made into the said upper limit or less, the addition amount of an acid increases and it becomes easy to add the anion which forms an acid as a counter ion to the cationic group introduce | transduced into the cellulose. When an anion that forms an acid is added to a cationic group introduced into cellulose, the electrostatic repulsion between the celluloses becomes larger, and it is considered that the defibration property becomes higher from that point.
On the other hand, if the pH is less than the lower limit, the device used for miniaturization may be corroded.
Further, in the acid addition step, when an excess acid is added, a washing step may be included once again before the miniaturization step described later.

<Defibration process>
The chemically treated fine fibers obtained above can be defibrated in the defibrating process. In the defibrating process, the fiber is usually defibrated using a defibrating apparatus to obtain a fine fiber-containing slurry, but the processing apparatus and the processing method are not particularly limited.
As the defibrating apparatus, a high-speed defibrator, a grinder (stone mill type pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type pulverizer, a ball mill, a bead mill, or the like can be used. Alternatively, as a defibrating apparatus, a device for wet grinding such as a disk type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater should be used. You can also. The defibrating apparatus is not limited to the above.

  Preferable defibrating methods include, but are not limited to, a high-speed defibrator, a high-pressure homogenizer, and an ultrahigh-pressure homogenizer that are less affected by the grinding media and less worried about contamination.

  In the defibrating process, it is preferable to dilute the fiber raw material with water and an organic solvent alone or in combination to form a slurry, but there is no particular limitation. As the dispersion medium, in addition to water, a polar organic solvent can be used. Preferable polar organic solvents include, but are not limited to, alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butyl alcohol. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether and tetrahydrofuran (THF). The dispersion medium may be one type or two or more types. Further, the dispersion medium may contain a solid content other than the fiber raw material, such as urea having hydrogen bonding property.

Specific examples for producing cationized fine cellulose fibers are described in more detail below. The cationized pulp to be refined is usually dispersed in a dispersion medium to form a dispersion. In the case of a dispersion, the solid content concentration of the cationized pulp dispersion is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass. If the solid content concentration of the cationized pulp dispersion is set to the lower limit value or more, the efficiency of the fine processing is improved, and if the solid content concentration is set to the upper limit value or less, blockage in the micro processing apparatus can be prevented.
Examples of the dispersion medium for dilution include water, an organic solvent, and a mixture of water and an organic solvent.

  In the refinement step, the fine cellulose fibers are defibrated so that the average fiber width is 2 to 1000 nm, preferably 2 to 100 nm, more preferably 2 to 50 nm, still more preferably 2 to 30 nm, and particularly preferably 2 to 15 nm. And refine. In order to set the average fiber width of the fine cellulose fibers in the above range, the defibration time, the shearing force applied to the cationized pulp for defibration, and the like may be appropriately adjusted.

<Other embodiments>
In the manufacturing method of the said embodiment, although it had the washing | cleaning process and the acid addition process, a washing | cleaning process and an acid addition process are arbitrary processes, You may abbreviate | omit at least one. That is, a micronization process may be performed after the cationization process, a micronization process may be performed after the washing process, or an acid addition process may be performed after the cationization process.

<Cation group amount>
The amount of cationic groups introduced into the cellulose fiber used in the present invention is not particularly limited. For example, 0.1 g to 2.0 mmol / g can be used per 1 g (dry weight) of cellulose fiber, and 0.15 to 1.8 mmol / g is preferable. This is because such an amount can suppress aggregation and maintain a dispersed state even when added to a high salt concentration underground layer treatment fluid. The amount of cationic groups introduced can be quantified by measuring the amount of nitrogen contained in the cellulose fiber using a trace nitrogen analyzer (for example, TN-110 manufactured by Dia Instruments). In this case, the cation group substance amount (mmol / g) per unit mass is obtained by dividing the nitrogen content (g) per gram of fine cellulose fiber containing a cation group by the number of nitrogen atoms contained in the cation group and the atomic weight of nitrogen. Is required.

<Characteristics of composition>
The composition for underground layer treatment containing the fine cellulose fiber having a cationic group obtained as described above has high salt resistance and excellent water-stopping property.
The underground layer treatment composition having salt resistance means that the viscosity of the fluid can be maintained when mixed with a well treatment fluid containing salt. The viscosity of the muddy water to be maintained means that the measured value when measured by the following method is 850 mPa · s or more. The viscosity is preferably 950 mPa · s or more, more preferably 20000 mPa · s or more.

Viscosity measurement:
Dilute with water so that the fiber solids content is 0.4% by mass, add 50 g of bentonite (for example, Kunigel V1, Kunimine Kogyo Co., Ltd.) to 1000 mL of the diluted solution, stir well, and let stand. Make a well-hydrated mud solution. Next, NaCl is added in an amount of 15% by mass and CaCl _{2 is} 2% by mass, and sodium hydroxide is further added so as to have a pH of 12, and the solid content of the fiber is 0.4% by mass. obtain. The viscosity of the obtained liquid is measured at 25 ° C. using a B-type viscometer (for example, analog viscometer T-LVT manufactured by BLOOKFIELD) at a rotation speed of 3 rpm (3 minutes).

  That the composition for underground layer treatment has high water-stopping means that the amount of drainage when the following water-stopping test is performed is 30 ml or less. The amount of drainage is preferably 20 ml or less, more preferably 10 ml or less.

Water-stop test:
The above-described 200 mL of high salt concentration / alkaline mud water with a fiber solid content of 0.4% by mass at 25 ° C. using an API standard filtration tester for 30 minutes at room temperature for 3 kg / cm ² G Measure the amount of drainage when pressure is applied.

  In general, the case where the pH is more than 8.0 and 11.0 or less may be called weak alkalinity. However, in the present invention, the term “alkaline” means that the pH exceeds 8.0, preferably Means when the pH exceeds 11.0. In the context of the present invention, the term “high salt concentration” refers to a case where the salt is contained in an amount of 1% by mass or more, more preferably 3% by mass or more (in the total amount when plural kinds of salts are contained).

[Use]
<Use as composition>
The composition for underground layer treatment containing the fine cellulose fiber having a cationic group of the present invention (simply referred to as “the composition for underground layer treatment containing the fine cellulose fiber of the present invention” or “the composition of the present invention”). Can be used for various purposes that take advantage of such properties, since the properties of the fluid can be variously modified by adding to the fluid. Although the use purpose (use) of the composition containing the fine cellulose fiber of the present invention is not particularly limited as long as it relates to the underground layer treatment, for example, the following can be mentioned.

  The composition containing the fine cellulose fiber of the present invention exhibits excellent salt resistance and does not decrease in viscosity even in a fluid having a high salt concentration. Therefore, the composition is increased in an inhibitory mud or a fracturing fluid to which a large amount of salt is added. Can be used as a sticking agent.

  Since the composition containing the fine cellulose fiber of the present invention can also exhibit excellent water-stopping properties, it can be used as an anti-sludge agent and a dehydration regulator in an underground layer treatment fluid.

  Since the composition containing the fine cellulose fiber of the present invention has thixotropic properties, it can exhibit excellent pit wall forming ability when used in muddy water. Further, when used as a cementing fluid, cement press-in can be facilitated. Therefore, it can be used as a pit wall forming agent or a cementing regulator.

  The composition containing the fine cellulose fibers of the present invention can also exhibit an emulsifying function by capturing oil droplets between the fine fiber networks in the underground layer treatment fluid, and therefore can be used as an emulsifier. I can expect. Specifically, it can be used for the use of an emulsion-based underground layer treatment fluid or the stabilization of an emulsion substance blended in the underground layer treatment fluid. The composition containing the fine cellulose fiber of the present invention can be used even in an environment of high temperature, for example, up to 300 ° C. The decomposition temperature of the fine cellulose fiber is 300 ° C., and because it has high crystallinity and does not have a melting point or a glass transition point, there is no settling like a general resin. Therefore, it can be used even in high deep water wells.

  The composition containing the fine cellulose fiber of the present invention can be used by being dispersed in an appropriate dispersion medium. The dispersion medium is not particularly limited as long as it can disperse fine cellulose fibers, and water, organic solvent, oil (for example, light oil, mineral oil, synthetic oil, edible oil, non-edible oil) or the like may be used. it can.

  The composition containing the fine cellulose fiber of the present invention can be in various forms such as a solid, a slurry, a dried product, and a concentrated (including gelled) product. Since it is dispersed in an aqueous dispersion medium when used, it may be processed to facilitate dispersion. When concentrating, the method is not particularly limited, and examples thereof include a method of adding a concentrating agent to a liquid containing fine fibers, a method using a commonly used dryer, and the like. Moreover, a well-known method, for example, the method described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used.

  The fine cellulose fiber contained in the composition of the present invention can be decomposed using a breaker. By decomposing it, it is possible to control the viscosity and prevent it from remaining in the underground layer. As the breaker, various components capable of decomposing cellulose fibers can be used. Examples include, but are not limited to, oxidizing agents such as ammonium persulfate and sodium persulfate, acids such as hydrochloric acid and sulfuric acid, and enzymes such as cellulase.

  The fine cellulose fiber contained in the composition of the present invention can be crosslinked with the aim of improving the viscosity effect and the like. As the crosslinking agent, various components capable of crosslinking the cellulose fiber can be used. Examples include, but are not limited to, borate, potassium hydroxide, nitrate, zirconium, titanium and the like.

<Fluid>
As described above, the composition of the present invention can be used for thickening prevention, mud prevention, dewatering control, emulsification, pit wall formation, cementing control, and resistance to temperature, acid, alkali and salt. Therefore, it can be used by adding to various fluids used in underground layer processing, for example, well drilling. Such fluids include fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid ), Stimulation fluid, sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid ), Drilling fluid, frac-packing fluid, water conformance fluid, gravel packing fluid and the like.

  When the composition containing the fine cellulose fiber of the present invention is contained in a fluid and used, the content is not particularly limited as long as the intended effect is exhibited. Typically, the fluid may contain cellulose fibers at a solids concentration (as the total amount of cellulose fibers) in the range of 0.005 to 10% by weight, preferably 0.01 to 5% by weight. More preferably, the solid content concentration of the cellulose fiber in the fluid is 0.05 to 2% by mass from the viewpoint of sufficiently exhibiting salt resistance and waterstop.

<Other components in the fluid>
In addition to the composition containing the fine cellulose fiber of the present invention, the fluid provided by the present invention may contain various components added to the fluid for conventional underground formation treatment. Examples of ingredients added include minerals, weighting agents, viscosity modifiers, dispersants, flocculants, anti-mudging agents, dehydration regulators, pH control agents, friction reducers, hydration expansion control agents, emulsifiers, surface activity Include, but are not limited to, agents, biocides, antifoams, scale inhibitors, corrosion inhibitors, temperature stabilizers, resin coating agents, crack supports, salts and proppants. Moreover, the component added may be not only one type but also two or more types.

  The cationized fine cellulose fibers coexist with an anionic additive to bond with each other, and it can be expected that the viscosity is controlled and the water stoppage is improved. Examples of the anionic additive include, but are not limited to, thickeners such as carboxymethylcellulose, xanthan gum, and guar gum, anionic minerals, anionic surfactants, and the like.

  When an anionic mineral coexists with a cationic fine cellulose fiber, they are bonded to each other, and an improvement in viscosity and an improvement in the strength of the mud wall film can be expected. Examples of the anionic mineral include, but are not limited to, bentonite (montmorillonite), kaolinite, halloysite, metahalloysite, illite, vermiculite, montmorillonite, chlorite, allophane, and humus.

  The weighting material is used for increasing the specific gravity of the fluid and preventing the stability of the bare pit wall and the ejection of gas, water and the like. Minerals such as barite and hematite can be used as the weighting material, but are not limited thereto.

  Viscosity modifiers are also called gelling agents, thickeners, and mud adjusters, and are used to optimize the viscosity of fluids. In addition to minerals such as bentonite, attabargite, sepiolite, and synthetic sukumite, water-soluble natural and synthetic polymers are used as components for this purpose. One preferred example of the water-soluble polymer is derived from a natural polysaccharide. Specific examples of viscosity modifiers include guar gum and guar gum derivatives, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, glyoxal-added hydroxypropylmethylcellulose, carboxymethylcellulose, and carboxyl as natural products or derived from natural products Water-soluble cellulose derivatives such as ethyl cellulose, gum arabic, alginic acid and its esters, alginate, elemi resin, gati gum, carrageenan, caraya gum, carob bean gum, thickening polysaccharide, tamarind gum, tragacanth gum, starch glycolate, starch salt, Examples include far cerulean, glucose, glucose polysaccharides, sucrose, xanthan gum, But it is not limited to these. Examples of the synthetic polymer include, but are not limited to, hydrolyzed polyacrylamide (PHPA polymer), polyvinyl alcohol, and polyacrylate polymer.

  The anti-sludge agent is used to prevent the underground layer treatment fluid from flowing out. Sawdust, straw, cellophane, cement, pulp fiber, polylactic acid, polyglycolic acid, polyarylate and the like can be used as the anti-sludge agent, but are not limited thereto.

  Dehydration modifiers are used to reduce dehydration and to enhance the protection of the walls. Examples of the dehydration regulator include, but are not limited to, sulfonated asphalt derivatives, starch derivatives, polyarylate, polyanionic cellulose-based polymers, and the like.

  An emulsifier is used to disperse in one liquid the other liquid, which is usually difficult to mix with it. As an emulsifier, glycerin ester, saponin, sucrose fatty acid ester, lecithin, polyethylene glycol, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyldodecyl ether, Polyoxyethylene decyl tetradecyl ether, polyoxyethylene behenyl ether, ethyl caprate, cetyl palmitate, stearyl stearate, cetyl octanoate, hexyldecyl isostearate, octyl isononanoate, dodecyl isononanoate, glyceryl stearate, glyceryl palmitate , Tri (caprylic acid capric acid) glycerin, sorbitan monostearate, sorbitan oleate, Propylene glycol tearate, propylene glycol oleate, propylene glycol laurate, glycol stearate, glycol dioleate, polyethylene glycol monostearate, polyoxyethylene glycol isostearate, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor Examples include, but are not limited to, oils, polyoxyethylene sorbitan fatty acid esters, and dimethylconcopolyols.

  Propant is a solid of about 0.5 mm, and is used to prevent the crack from being closed by being pushed into the crack during fracturing or the like. Examples of proppants include, but are not limited to, sand, glass beads, ceramic particles and resin-coated sand.

(muddy water)
One preferred embodiment is mud used during well drilling, comprising a composition containing the fine cellulose fibers of the present invention. The cellulose fiber content in the muddy water is not particularly limited as long as the intended effect is exhibited. The muddy water contains cellulose fibers at a solid content concentration (as the total amount of cellulose fibers), for example, 0.004 to 40% by mass, preferably 0.04 to 4% by mass, and preferably 0.08 to 2% by mass. More preferably.

  The mud used for well excavation is generally used to remove the moat from the bottom of the well and transport it to the ground. The mud also controls the pressure in the well to prevent unintended flow of fluid into the well and ejection to the ground, and protects the well wall to prevent the collapse of the underground layer. It also reduces the friction with the walls and cools downhole equipment. It also has the role of providing underground information by transporting moat and gas. The muddy water includes bentonite muddy water, lignosulfonate muddy water, KCl polymer muddy water, oil-based muddy water, and the like, and various muddy waters are provided by this embodiment.

  In general, bentonite mud is inexpensive and easy to handle, but it is weak against salt and cement and easily gelled. In order to supplement these determinations, carboxymethylcellulose or the like may conventionally be added, but the present invention can provide bentonite mud with higher performance.

  According to this embodiment, a dispersion mud containing the composition containing the fine cellulose fiber of the present invention is provided. Such muddy water may contain a conventional lignosulfonate (sometimes referred to as lignin sulfonic acid), lignite (humic acid derivative), a pH adjuster (for example, sodium hydroxide), and a weighting agent as a dispersant. The dispersion mud provided by this embodiment has a mudstone protection function, easy control of viscosity and specific gravity, temperature (usually lignosulfonate mud is used at a temperature of about 175 ° C., lignite mud is used at a temperature of about 190 It can be expected that the yield strength of salt, cement, etc. is further enhanced compared to conventional lignosulfonate mud.

  The mud provided by this embodiment can also be configured as KCl mud. It is known that K ions are very excellent in the action of suppressing the swelling and dispersion of clays. On the other hand, it has been used in combination with chitansan gum and partially hydrolyzed polyacrylamide (PHPA) polymer, which can exhibit thickening and protective colloid properties even in liquids containing a large amount of K ions because of its cohesive strength. It was. In the present embodiment, a composition containing fine cellulose fibers provided by the present invention can be used together with or in place of the chitansan gum and PHPA. The KCl mud provided by the present embodiment has a mudstone protection function, ease of control of viscosity and specific gravity, and proof strength due to salt, cement, etc., as compared with the conventional KCl-polymer mud. I can expect.

  The muddy water provided by this embodiment can also be configured as an oil-based muddy water. The oil-based muddy water includes an invert emulsion oil mud, which is an oil mud having an oil content of 95% or more, and a water-in-oil emulsion prepared using 15 to 35% water and an emulsifier. In general, oil-based mud is less susceptible to hydration and swelling of the mudstone layer, high-temperature stability, lubricity, prevention of productivity failure due to water intrusion into the oil layer, and metal corrosion less than water-based mud. There are advantages such as little deterioration due to corruption. By this embodiment, it can be expected that an improved oil-based mud is provided while taking advantage of these characteristics.

(Fracturing fluid)
One preferred embodiment is a fracturing fluid used in hydraulic fracturing comprising a composition containing the fine cellulose fibers of the present invention. The fracturing fluid is added with a high concentration of salt to prevent the collapse of the formation. Furthermore, in order to promote the crosslinking reaction of thickeners such as guar gum, it may be adjusted to be highly alkaline. Since the fine cellulose fiber of the present invention is excellent in salt resistance and alkali resistance, it is suitable for a fracturing fluid. The content of the cellulose fiber in the fracturing fluid is not particularly limited as long as the intended effect is exhibited. The fracturing fluid contains cellulose fibers at a solid content concentration (as the total amount of cellulose fibers), for example, 0.002 to 20% by mass, preferably 0.02 to 2% by mass, and preferably 0.04 to 1% by mass. % Content is more preferable.

  The fracturing fluid generally contains about 90 to 95% by mass of water or an organic solvent as a solvent or dispersion medium, and about 5 to 9% by mass of proppant (support). Further, in some cases, it contains about 0.5 to 1% by mass of various additives such as gelling agents, scale inhibitors, acids for dissolving rocks, friction reducing agents and the like. These components and additives can also contain the fracturing fluid provided by this embodiment in a similar range.

  In addition to the stable dispersion of proppant in the fracturing fluid, the fine cellulose fibers can be used for flexible viscosity control by further improving the viscosity due to the crosslinking reaction or by decomposing after use to lower the viscosity of the fluid. it can. It can also be used as a degradable anti-sludge agent in a fracturing fluid. By preventing the mud, it is possible to easily apply pressure in the mine, so that a better crack can be formed. Adding normal anti-sludge agent to the fracturing fluid may block the gas production flow path, but the anti-sludge agent made of fine cellulose fibers will block the production flow path if it decomposes after use. There is nothing.

(Cementing fluid)
One preferred embodiment is a cementing fluid comprising a composition containing the fine cellulose fibers of the present invention. The cellulose fiber content in the cementing fluid is not particularly limited as long as the intended effect is exhibited. The cementing fluid contains cellulose fibers at a solid content concentration (as the total amount of cellulose fibers), for example, 0.001 to 40 mass%, preferably 0.01 to 20 mass%, preferably 0.05 to 5 mass%. It is more preferable to contain.

  The cementing fluid may be a general-purpose cement such as tricalcium silicate or a high temperature durable cement such as a class G cement used for high temperature wells. In order to optimize the cementing time, a caking agent such as a cement fast hardener or a cement slow hardener can be used as an additive. Cement dispersants, fluidity improvers, low specific gravity, low dehydrated cement additives, and the like can also be used. Others include dehydration regulators, strength stabilizers, weighting materials, cement spacer additives for improved replacement efficiency and underground cleaning, chemical wash additives for wall cleaning, cement slurry defoamers, scale inhibitors, Anti-sludge agent, calcium aluminate, sodium polyphosphate, fly ash, foaming agent, foam stabilizer, and a sufficient amount of gas to form foam may be added. In order to provide elasticity to the cured cementing fluid, the fluid may optionally include inert and ground rubber particles.

  The fine cellulose fibers form a three-dimensional network in water, and even fine substances can be stably dispersed. For example, cement particles of 10 μm or less are present in the cementing fluid. Even if the fine cellulose fiber is a particle of 10 μm or less, it can be stably dispersed. Hydrophobic particles can also be stably dispersed in water, for example, hydrophobically treated pigment particles, minerals, and the like can be stably dispersed. Moreover, since the fine cellulose fiber has high hydrophilicity, water separation of the cementing fluid can be suppressed. Since salt resistance is also high, compatibility with a cementing fluid containing a large amount of calcium is also good.

Further, in a high temperature well containing carbon dioxide such as a geothermal well, a cementing fluid that does not deteriorate in the presence of carbon dioxide containing salt water is desired. Also, the cement composition used in geothermal wells and similar wells is lightweight, for example having a density in the range of about 9.5 to about 14 pounds / gallon (about 1.14 to about 1.68 g / cm ³ ). Is preferred. According to this embodiment, the provided cementing fluid can also be configured in such a density range.

[Treatment method of underground layer, production method of petroleum resources]
The present invention also provides a method for treating an underground formation using the composition of the present invention or the fluid described above. Underground layers (sometimes referred to as geological formations) include undersea subsurface layers.

  Subsurface processing includes drilling of wells used for various purposes. Wells include exploratory well or wildcat, appraisal well, exploratory well, exploration well, delineation well, development well, production well, injection Examples include, but are not limited to, injection wells, observation wells, service wells, and the like.

Moreover, the following are contained in the process of an underground layer.
・ Cementing: This is mainly performed to fix the casing by filling the gap between the casing and the wall of the well after digging the well.
-Well survey, well logging: This includes mud logging. The muddy water logging is for observing and analyzing gas and swarf in the circulating drilling mud, so that the oil and gas layer can be detected at an early stage and the lithology being excavated can be known.
• Petroleum resource recovery: This includes water flooding and chemical flooding.
-Well stimulation: This is done for the purpose of improving productivity by improving the properties of the wells and reservoirs around the wells. This includes washing with hydrochloric acid or the like, acidizing, and hydraulic fracturing (hydrofracturing, fracking) that creates a crack in the reservoir to ensure fluid flow. Furthermore, in the case of production from the sand layer, sand control and sand-containing fluids are used to prevent sand from flowing into the wells and preventing sand-containing fluids from damaging tubing and equipment. Includes plastic consolidation, which presses into the bed to harden the sandstone.
-Well finishing using water-based mud, oil-based mud, chemical fluid or brine.
-Fracturing using high-pressure fracturing fluid to create passages (breaks, fractures) in tight underground layers with low permeability.
-Well workover.
・ Abandoned mine treatment.

  The present invention also provides a method for producing petroleum resources using the composition or fluid obtained according to the present invention. Petroleum resources refer to all mineral, hydrocarbons, solids, liquids and gases that exist underground. Typical examples of petroleum resources are the general categories of liquid oil and gaseous natural gas. Petroleum resources include conventional oil (oil), natural gas, tight sand gas, shale oil, tight oil, heavy oil, super heavy oil, shale gas, coal seam gas, bitumen, heavy oil, oil. Contains sand, oil shale and methane hydrate.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

(Production Example 1)
A sheet (solid content concentration: 90% by mass) made of softwood bleached kraft pulp (NBKP) was taken out in an amount corresponding to 4.0 g in an absolutely dry mass. Using a hand mixer (manufactured by Osaka Chemical Co., Ltd., Labo Milcer PLUS), it was treated at a rotation speed of 20,000 rpm for 15 seconds to form cotton-like fluffing pulp (solid content concentration 90 mass%).
Next, 0.4 g of a cationizing agent (Kachio Master G, manufactured by Yokkaichi Chemical Co., Ltd., glycidyltrimethylammonium chloride, pure content: 73.1% by mass, moisture content: 20.2% by mass) and 1.5N aqueous sodium hydroxide solution 2 .8 g was mixed. The resulting cationizing agent mixture is added to the fluffing pulp using a spray, placed in a polyvinylidene chloride bag, and the bag is manually squeezed to make the mixture uniformly into the pulp. The sample for reaction was prepared by infiltration. The pH of this reaction sample was 13 at 25 ° C.
Then, the air in a bag was removed and it was made to react at 80 degreeC for 1 hour, and the cationized pulp was obtained. 400 ml of ion-exchanged water was added to the resulting cationized pulp, washed with stirring, and then dehydrated. The washing / dehydration process is repeated four times, and after the fourth dehydration, 0.1N hydrochloric acid and ion-exchanged water are added to the washed cationized pulp to obtain a cationization having a pH of 4 and a solid content concentration of 0.5% by mass. A pulp dispersion was obtained. Next, the cationized pulp dispersion was fibrillated by using a high-speed rotating defibrating apparatus (Cleamix-2.2S, manufactured by MTechnic Co., Ltd.) for 30 minutes at 21500 rpm. A fine cellulose fiber 1 was obtained.

(Production Example 2)
The cationized fine cellulose was prepared in the same manner as in Production Example 1 except that the cationizing agent mixture was changed to one obtained by mixing 0.6 g of the cationizing agent and 3.2 g of a 1.3N aqueous sodium hydroxide solution. Fiber 2 was obtained.

(Production Example 3)
A cationized fine cellulose was prepared in the same manner as in Production Example 1 except that the cationizing agent mixture was changed to a mixture obtained by mixing 4.0 g of a cationizing agent and 3.2 g of a 1.3N sodium hydroxide aqueous solution. Fiber 3 was obtained.

(Production Example 4)
A cationized fine cellulose was prepared in the same manner as in Production Example 1 except that the cationizing agent mixture was changed to one obtained by mixing 6.0 g of a cationizing agent and 3.2 g of a 1.3N sodium hydroxide aqueous solution. Fiber 4 was obtained.

(Production Example 5)
Cationized fine cellulose was prepared in the same manner as in Production Example 1 except that the cationizing agent mixture was changed to one obtained by mixing 15.0 g of cationizing agent and 15.0 g of a 1.3N aqueous sodium hydroxide solution. Fiber 5 was obtained.

(Experimental example 1)
The suspension containing the cationized fine cellulose fiber 1 produced in Production Example 1 was diluted so that the fiber solid content concentration was 0.4% by mass. 50 g of bentonite (Kunigel V1, Kunimine Kogyo Co., Ltd.) was added to 1000 mL of the diluted solution, stirred at 3000 rpm for 60 minutes, and then allowed to stand for 24 hours to produce fully hydrated mud water. Then, the NaCl concentration is added to 15% by mass, the CaCl ₂ concentration is added to 2% by mass, sodium hydroxide is added to have a pH of 12, and the viscosity is measured by the following method (measurement of viscosity). did. Moreover, the amount of drainage was measured by the following method (water-stop test) using the obtained muddy water. The results are shown in Table 1.

(Experimental example 2)
In Experimental Example 1, all tests were performed in the same manner as in Experimental Example 1 except that the cationized fine cellulose fiber 2 produced in Production Example 2 was used instead of the cationized fine cellulose fiber 1.

(Experimental example 3)
In Experimental Example 1, all tests were performed in the same manner as in Experimental Example 1 except that the cationized fine cellulose fiber 3 produced in Production Example 3 was used instead of the cationized fine cellulose fiber 1.

(Experimental example 4)
In Experimental Example 1, all tests were performed in the same manner as in Experimental Example 1 except that the cationized fine cellulose fiber 4 produced in Production Example 4 was used instead of the cationized fine cellulose fiber 1.

(Experimental example 5)
In Experimental Example 1, all tests were performed in the same manner as in Experimental Example 1 except that the cationized fine cellulose fiber 5 produced in Production Example 5 was used instead of the cationized fine cellulose fiber 1.

(Experimental example 6)
Carboxymethyl cellulose (500.0 to 900.0 mPa · s (2% by mass, solvent: water, 25 ° C.), Tokyo Chemical Industry Co., Ltd.) was added in place of the fine cellulose fiber, and a 0.4% by mass diluent was used. Were tested in the same manner as in Experimental Example 1.

(Test method)
<Measurement of cationic group amount>

  The content of the cationic group can be quantified by measuring the amount of nitrogen contained in the fine cellulose fiber using a trace nitrogen analyzer (for example, TN-110 manufactured by Dia Instruments). In this case, the cation group substance amount (mmol / g) per unit mass is obtained by dividing the nitrogen content (g) per gram of fine cellulose fiber containing a cation group by the number of nitrogen atoms contained in the cation group and the atomic weight of nitrogen. Is required.

<Measurement of viscosity>
The viscosity of the obtained muddy water was measured at 25 ° C. using a B-type viscometer (manufactured by BLOOKFIELD, analog viscometer T-LVT) at a rotation speed of 3 rpm (3 minutes).

<Water-stop test>
200 mL of the obtained muddy water was measured at 25 ° C. using a filtration tester according to the API standard, and the amount of filtrate when 3 kg / cm ² G was pressurized at room temperature for 30 minutes was measured. That is, it can be said that the smaller the amount of drainage, the better the water stop performance.

  The results are shown in the table below.

  As shown in Table 1, when cationized fine cellulose fibers 2 to 4 (Experimental Examples 2 to 4) were mixed with high salt concentration mud water, it was confirmed that the high viscosity was maintained and the water stopping property was high. .

  According to the present invention, fine cellulose fibers are blended in muddy water having a high salt concentration used in underground layer treatment. The present invention is particularly useful for the treatment of underground formations where high viscosity is maintained and high water stopping properties are expected.

Claims (17)

A composition for treating an underground layer, comprising fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g. The composition of Claim 1 whose fiber width of a fine cellulose fiber is 200 nm or less. The composition according to claim 1 or 2, for use by adding to an alkaline underground fluid. The composition according to any one of claims 1 to 3, which has salt resistance. The composition according to any one of claims 1 to 4, which has a water-stopping property. Muddy water, fracturing fluid, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid, stimulation fluid ), Sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid, drilling fluid ), A frac-packing fluid, a water conformance fluid, or a gravel packing fluid for use. A composition according to 1. The composition according to any one of claims 1 to 6, wherein the viscosity measured by the following measurement method is 20000 mPa · s or more.
(Measurement method of viscosity)
Dilute with water so that the fiber solids content is 0.4% by mass, add 50 g of bentonite to 1000 mL of the diluted solution, stir well, let it stand, and make a fully hydrated mud solution, Next, NaCl is added in an amount of 15% by mass and CaCl _{2 is} 2% by mass, and sodium hydroxide is further added so as to have a pH of 12, whereby a muddy water having a fiber solid content of 0.4% by mass is obtained. The viscosity is measured at 25 ° C. using a B-type viscometer at 3 rpm for 3 minutes. A fluid for underground layer treatment comprising the composition according to any one of claims 1 to 7 , wherein the solid content concentration of the cellulose fiber is 0.05 to 2 mass%. The composition according to any one of claims 1 to 7 , and a weighting agent, a viscosity modifier, a dispersing agent, a flocculant, a mud prevention agent, a pH control agent, a friction reducing agent, a hydration expansion controlling agent, and an emulsifier. Including any one selected from the group consisting of: surfactants, biocides, antifoams, scale inhibitors, corrosion inhibitors, temperature stabilizers, resin coating agents, crack supports, salts, and proppants. Layer processing fluid. An underground layer treatment fluid comprising the composition according to any one of claims 1 to 7 and an anionic additive. The underground layer treatment fluid according to claim 10 , wherein the anionic additive is a mineral. The fluid according to any one of claims 8 to 11 , which is a fracturing fluid, a muddy water or a cementing fluid. A composition according to any one of claims 1 to 7 or using a fluid according to any one of claims 8 to 12, the processing method of the subterranean formation. A method for producing petroleum resources, wherein the composition according to any one of claims 1 to 7 or the fluid according to any one of claims 8 to 12 is used. A method for producing a fluid for treating an underground layer, comprising a step of adding an aqueous dispersion of fine cellulose fibers having a cationic group of 0.15 to 1.8 mmol / g to a fluid. Concentrate or dry the fine cellulose fiber dispersion,
Method of manufacturing resulting concentrate or dry product is redispersed in an aqueous solvent comprises obtaining re-dispersion composition according to any one of claims 1-7. The production method according to claim 16 , wherein the concentration is carried out by a thickener and / or a dryer.