JP6569482B2 - Underground layer treatment composition, underground layer treatment fluid, method for producing underground layer treatment fluid, and method for treating underground layer - Google Patents

Description

  The present invention relates to a composition for treating an underground layer, a fluid for treating the underground layer, a method for producing the fluid for treating the underground layer, and a method for treating the underground layer. Specifically, the present invention relates to a composition for treating an underground layer containing fine fibrous cellulose and a nonionic water-soluble polymer, a fluid for treating an underground layer containing the composition for treating the underground layer and a fluid, and a method for treating the underground layer. The present invention relates to a method for producing a working fluid. The underground layer treatment fluid is used in a method for treating the underground layer.

  In recent years, materials that use reproducible natural fibers have attracted attention due to the substitution of petroleum resources and the growing environmental awareness. Among natural fibers, fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, in particular, fibrous cellulose (pulp) derived from wood has been widely used mainly as a paper product so far.

  As the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Sheets and composites containing fine fibrous cellulose significantly increase the tensile strength because the contact points between fibers are remarkably increased. Moreover, transparency is greatly improved because the fiber width is shorter than the wavelength of visible light. It is also known that such fine fibrous cellulose can be used for applications such as thickeners.

  For example, Patent Document 1 discloses a viscous aqueous composition containing fine fibrous cellulose. Patent Documents 2 and 3 disclose viscous aqueous compositions in which fine fibrous cellulose and other thickeners are combined. In Patent Document 2, carboxymethyl cellulose, xanthan gum, dextrin and the like are listed as thickeners other than fine fibrous cellulose. In patent document 3, nonionic thickening polysaccharide is mentioned as thickeners other than a fine fibrous cellulose. In Patent Documents 1 to 3, the addition of a viscous aqueous composition to cosmetics, pharmaceuticals, foods, and the like has been studied.

  By the way, natural resources such as gas, oil or water existing in the underground layer or underground area are usually recovered by digging the drilling hole to the underground layer while circulating the drilling fluid in the drilling hole. As the drilling fluid, for example, a fracturing fluid, a fluid for processing an underground layer such as a muddy water, a cementing fluid, or the like is used. Many of these fluids contain a thickener, and for example, natural polysaccharides such as xanthan gum, cellulose derivatives such as carboxymethyl cellulose, and synthetic polymers such as polyacrylamide and polyvinyl alcohol are used.

JP 2010-037348 A JP 2008-106178 A JP 2012-126788 A

  As described above, the use of fine fibrous cellulose as a thickener has been studied. It has also been studied to combine a fine fibrous cellulose with another thickener to form a viscous aqueous composition. However, Patent Documents 1 to 3 do not examine the use of such a viscous aqueous composition as a fluid for underground layer treatment, and whether or not it has physical properties necessary as a fluid for underground layer treatment. It was unknown.

  In addition to having an appropriate viscosity, the underground layer treatment fluid for recovering natural resources such as shale gas and shale oil has not only an appropriate viscosity, but also heat resistance that can maintain an appropriate viscosity even in the underground layer, and viscosity as needed. Is required to be degradable and can be recovered after subsurface treatment. As described above, various properties are required for the underground formation fluid, and the development of an underground formation fluid that satisfies these requirements has been demanded.

  Therefore, in order to solve such problems of the prior art, the present inventors have heat resistance that can maintain an appropriate viscosity in the underground layer in addition to having an appropriate viscosity, and a decomposition that reduces the viscosity when necessary. In order to provide a composition for underground layer treatment that can be used as a fluid for underground layer treatment that has both a good property and good recoverability, studies have been conducted.

As a result of intensive studies to solve the above problems, the present inventors combined a non-ionic water-soluble polymer with a fine fibrous cellulose having a fiber width of 1000 nm or less in the underground layer treatment composition. It has been found that by using it, a fluid for treating the underground layer having an appropriate viscosity, heat resistance that can maintain the appropriate viscosity even in the underground layer, decomposability that lowers the viscosity when necessary, and good recoverability can be obtained. .
Specifically, the present invention has the following configuration.

[1] A composition for treating an underground layer comprising fine fibrous cellulose having a fiber width of 1000 nm or less and a nonionic water-soluble polymer.
[2] The composition for underground layer treatment according to [1], wherein the content of the nonionic water-soluble polymer is 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the fine fibrous cellulose.
[3] The underground treatment composition according to [1] or [2], wherein the nonionic water-soluble polymer is guar gum.
[4] The composition for underground layer treatment according to any one of [1] to [3], wherein the fine fibrous cellulose has an anionic substituent.
[5] The composition for underground layer treatment according to any one of [1] to [4], wherein the fine fibrous cellulose is phosphorylated cellulose or maleated cellulose.
[6] The microfibrous cellulose has an anionic substituent of 0.1 mmol / g or more and 3.5 mmol / g or less per gram of the fine fibrous cellulose, for underground layer treatment according to any one of [1] to [5] Composition.
[7] The underground treatment composition according to any one of [1] to [6], further comprising an ionic water-soluble polymer.
[8] The composition for underground layer treatment according to any one of [1] to [7], wherein the content of the fine fibrous cellulose is 3% by mass or more based on the total mass of the composition for underground layer treatment.
[9] A fluid for treating an underground layer, comprising fine fibrous cellulose having a fiber width of 1000 nm or less, a nonionic water-soluble polymer, and a fluid.
[10] The underground layer treatment fluid according to [9], further including a decomposition agent.
[11] The underground layer treatment fluid according to [9] or [10], wherein the decomposing agent is an oxidizing agent.
[12] The underground layer treatment fluid according to any one of [9] to [11], further including a granular material having an average particle diameter of 0.1 mm to 10 mm.
[13] The underground according to any one of [9] to [12], wherein the viscosity at a liquid temperature of 25 ° C. measured with a B-type viscometer is 3 rpm and the viscosity at a measurement time of 3 minutes is 3000 mPa · s or more. Layer processing fluid.
[14] The viscosity of the supernatant liquid after adding ammonium peroxodisulfate to the underground layer treatment fluid to 0.06% by mass and allowing to stand at 70 ° C. for 6 hours. The fluid for underground layer treatment according to any one of [9] to [13], wherein the viscosity at a rotation speed of 3 rpm and a measurement time of 3 minutes measured using a viscometer is 800 mPa · s or less.
[15] A step of mixing fine fibrous cellulose having a fiber width of 1000 nm or less and a nonionic water-soluble polymer to obtain a composition for treating an underground layer, and a step of mixing a composition for treating an underground layer and a fluid, The manufacturing method of the fluid for underground layer processing containing this.
[16] The method for producing a fluid for underground formation treatment according to [15], further including a step of adding a decomposing agent after the step of obtaining the composition for underground formation treatment.
[17] The underground treatment fluid according to [15] or [16], further including a step of adding a granular material having an average particle diameter of 0.1 mm or more and 10 mm or less after the step of obtaining the composition for treatment of the underground formation. Manufacturing method.
[18] A method for treating an underground layer including a step of causing the underground layer processing fluid according to any one of [9] to [14] to flow into the underground layer.
[19] After the step of flowing the underground layer treatment fluid into the underground layer, the method further includes a step of recovering the treated fluid containing at least the fine fibrous cellulose, the nonionic water-soluble polymer, and the fluid [18] ] The processing method of the underground layer of description.
[20] Between the step of allowing the underground layer processing fluid to flow into the underground layer and the step of recovering the treated fluid, a step of sinking particulate matter having an average particle diameter of 0.1 mm to 10 mm is included [18. ] Or the underground layer processing method according to [19].

  According to the present invention, an underground layer treatment that can be an underground layer treatment fluid that has appropriate viscosity, heat resistance that can maintain an appropriate viscosity even in the underground layer, decomposability that lowers viscosity when necessary, and good recoverability. The composition for use can be obtained. Since the underground layer treatment fluid obtained in the present invention has the above-mentioned characteristics, it is excellent in the dispersibility (supportability) of the granular material used for the underground layer treatment represented by proppant during mixing. The particulate matter can be easily settled, and the fluid can be recovered in a state of low viscosity after the underground layer treatment.

FIG. 1 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity for a fiber material having a phosphate group. FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity for a fiber material having a carboxyl group.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

(Underground treatment composition)
The present invention relates to a composition for treating an underground layer comprising fine fibrous cellulose having a fiber width of 1000 nm or less and a nonionic water-soluble polymer. Since the underground treatment composition of the present invention is a composition having an appropriate viscosity according to the treatment use of the underground formation, it can also be used as a thickening agent for underground formation treatment.

The underground layer treatment fluid is prepared by further mixing a fluid such as water with the underground layer treatment composition of the present invention. Such underground layer treatment fluid has an appropriate viscosity. For this reason, the underground processing fluid has dispersibility (supportability) that can uniformly disperse granular materials such as proppant transported to the underground layer. Moreover, although an underground layer area | region is high temperature with the heat | fever of magma etc., the fluid for underground layer processing obtained by this invention can maintain appropriate viscosity also in an underground layer. That is, the underground layer processing fluid has heat resistance. Furthermore, the underground layer treatment fluid obtained by the present invention has a property that the viscosity is lowered when necessary by a decomposition agent or the like. When the viscosity of the underground layer treatment fluid decreases, the transported particulate matter such as proppant can settle and stay in place. And the post-processed fluid with reduced viscosity has the advantage that it can be easily recovered. In addition to having a low viscosity after treatment, the underground layer treatment fluid obtained in the present invention has good recoverability because gelation is suppressed even when time passes. As described above, the underground layer treatment fluid obtained from the underground layer treatment composition of the present invention has an appropriate viscosity, heat resistance that can maintain an appropriate viscosity even in the underground layer, and a degradability that reduces the viscosity when necessary. And good recoverability.
It is known that thickening can be obtained in a composition containing conventional fine fibrous cellulose, but in the composition for treating an underground layer, the purpose of treating the underground layer cannot be achieved only by increasing the viscosity. . In addition to thickening before treatment (dispersibility that can uniformly disperse particulates such as proppant), the composition for underground layer treatment is not the only one that has all the characteristics of heat resistance, decomposability and recoverability. The objective can be achieved. The present invention has discovered new properties such as heat resistance, decomposability, and recoverability that cannot be predicted from conventional compositions, and relates to a completely new composition for use in underground formation treatment.

Since the underground layer treatment composition itself contains a certain amount or more of water, the underground layer treatment composition itself can be used as the underground layer treatment fluid. In this case, the physical properties specified in the item of the underground layer treatment fluid are the physical properties of the underground layer treatment composition.
However, since most of the underground layer processing fluid is moisture, it is preferable that the fluid is prepared at the processing site immediately before processing in consideration of transportation costs and the like. For this reason, the underground layer treatment composition is preferably concentrated to some extent, and the underground layer treatment fluid is preferably a fluid obtained by mixing the concentrated underground layer treatment composition and the fluid. Specifically, the content of the fine fibrous cellulose in the underground layer treatment composition may be 3% by mass or more with respect to the total mass of the underground layer treatment composition, and is 5% by mass or more. May be.

<Nonionic water-soluble polymer>
The underground layer treatment composition of the present invention contains a nonionic water-soluble polymer. It is considered that the nonionic water-soluble polymer stabilizes the dispersion by preventing aggregation of fine fibrous cellulose due to the steric hindrance due to the swelling action in the composition for treating the underground layer and the fluid for treating the underground layer. Such an effect is considered to appear as a synergistic effect when a combination of fine fibrous cellulose and a nonionic water-soluble polymer is used. Moreover, the nonionic water-soluble polymer can also suppress reaggregation after the fine fibrous cellulose is decomposed, and can maintain such a reaggregation suppressing effect for a long time.

  The content of the nonionic water-soluble polymer in the underground layer treatment composition of the present invention is preferably 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the fine fibrous cellulose. The content of the nonionic water-soluble polymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more with respect to 100 parts by mass of the fine fibrous cellulose, and 5 parts by mass or more. Is more preferable. The content of the nonionic water-soluble polymer is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further preferably 60 parts by mass or less, and 50 parts by mass or less. It is still more preferable that it is 30 mass parts or less.

Nonionic water-soluble polymers include water-soluble polysaccharides such as tamarind gum, glucomannan, guar gum, locust bean gum, pullulan, cellulose derivatives such as alkyl cellulose and hydroxyalkyl cellulose, raw starch, etherified starch, esterification Examples thereof include, but are not limited to, starches such as starch and amylose, synthetic polymers such as polyvinyl alcohol, polyacrylamide, polyoxyalkylene alkyl ether, polyvinyl pyrrolidone, and polyglycerin. Among these, the nonionic water-soluble polymer is preferably at least one selected from water-soluble polysaccharides such as tamarind gum, glucomannan, guar gum, locust bean gum, pullulan, and more preferably guar gum. .
In the present specification, the term “nonionic” means that the molecule does not have an ionic functional group that is ionically dissociated.

<Fine fibrous cellulose>
Although it does not specifically limit as a fibrous cellulose raw material for obtaining a fine fibrous cellulose, It is preferable to use a pulp from the point of being easy to acquire and cheap. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached craft Chemical pulps such as pulp (OKP) are listed. Moreover, semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), mechanical pulps such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are not particularly limited. Non-wood pulp includes 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, chitin, chitosan, etc., but is not particularly limited. . The deinking pulp includes deinking pulp made from waste paper, but is not particularly limited. The pulp of this embodiment may be used alone or in combination of two or more. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refinement (defibration) is high, and the degradation of cellulose in the pulp is small, and the fineness of long fibers with a large axial ratio is high. This is preferable in that fibrous cellulose is obtained. Of these, kraft pulp and sulfite pulp are most preferably selected. Sheets containing long fibrous fine fibrous cellulose having a large axial ratio tend to provide high strength.

  The average fiber width of the fine fibrous cellulose is 1000 nm or less as observed with an electron microscope. The average fiber width is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and further preferably 2 nm or more and 10 nm or less, but is not particularly limited. When the average fiber width of the fine fibrous cellulose is less than 2 nm, the physical properties (strength, rigidity, dimensional stability) as the fine fibrous cellulose tend to be difficult to be expressed because the cellulose molecules are dissolved in water. . The fine fibrous cellulose is monofilamentous cellulose having a fiber width of 1000 nm or less, for example.

  Measurement of the average fiber width of the fine fibrous cellulose by observation with an electron microscope is performed as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to prepare a sample for TEM observation. To do. 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 lines X and Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read. The average fiber width (sometimes simply referred to as “fiber width”) of fine fibrous cellulose is an average value of the fiber widths read in this way.

  The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and particularly preferably 0.1 μm or more and 600 μm or less. By making the fiber length within the above range, the destruction of the crystalline region of the fine fibrous cellulose can be suppressed, and the slurry viscosity of the fine fibrous cellulose can be made an appropriate range. Note that the fiber length of the fine fibrous cellulose can be determined by image analysis using TEM, SEM, or AFM.

The fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has a type I crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromatized with graphite. Specifically, it can be identified by having typical peaks at two positions of 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °.
The proportion of the I-type crystal structure in the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more.

  The ratio of the crystal part contained in the fine fibrous cellulose is not particularly limited in the present invention, but it is preferable to use cellulose having a crystallinity obtained by an X-ray diffraction method of 60% or more. The degree of crystallinity is preferably 65% or more, more preferably 70% or more. In this case, further excellent performance can be expected in terms of heat resistance and low linear thermal expansion. The degree of crystallinity is obtained by measuring an X-ray diffraction profile and determining the crystallinity by a conventional method (Seagal et al., Textile Research Journal, 29, 786, 1959).

<Chemical treatment>
Fine fibrous cellulose can be obtained by defibrating a cellulose raw material. Moreover, in this invention, it is preferable to perform a chemical process to a cellulose raw material before a fibrillation process, and to add a substituent to a fine fibrous cellulose. The substituent added to the fine fibrous cellulose is preferably an ionic substituent, and more preferably an anionic substituent. Examples of the anionic substituent include a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), at least one substituent selected from a carboxyl group and a sulfone group. it can. Among these, the anionic substituent is preferably at least one selected from a phosphate group and a carboxyl group.

  In the present specification, fine fibrous cellulose having a phosphate group or a substituent derived from a phosphate group may be referred to as phosphorylated cellulose. Moreover, the fine fibrous cellulose which has a carboxyl group may be called carboxylated cellulose. Further, fine fibrous cellulose in which cellulose and one carboxyl group of dicarboxylic acid are ester-bonded may be referred to as dicarboxylic acid esterified cellulose. That is, the fine fibrous cellulose used in the present invention is preferably at least one selected from phosphorylated cellulose and carboxylated cellulose, and is at least one selected from phosphorylated cellulose and dicarboxylic esterified cellulose. More preferred is at least one selected from phosphorylated cellulose and maleated cellulose, and even more preferred is phosphorylated cellulose.

Carboxy-oxidized cellulose includes TEMPO-oxidized cellulose prepared by oxidizing with oxidant such as TEMPO and sodium hypochlorite. The carboxylated cellulose includes dicarboxylic acid esterified cellulose, and examples of the dicarboxylic acid esterified cellulose include maleated cellulose prepared by addition to maleic anhydride. Specifically, the monosaccharide structure of TEMPO oxidized cellulose is exemplified as the following structure a, and the monosaccharide structure of maleated cellulose is exemplified as the following structure b.

In the present invention, the carboxylated cellulose is preferably a dicarboxylic acid esterified cellulose such as maleated cellulose. Dicarboxylic acid esterified cellulose is one in which one carboxyl group of maleic anhydride or dicarboxylic acid is ester-bonded to cellulose. By having such an ester bond, it is considered that re-aggregation after fine fibrous cellulose is decomposed can be more effectively suppressed.
The structure can be analyzed using, for example, NMR measurement, MS fragment analysis, UV analysis, or the like.

  The fine fibrous cellulose used in the present invention preferably has an anionic substituent of 0.1 mmol / g to 3.5 mmol / g per 1 g (mass) of the fine fibrous cellulose. The fine fibrous cellulose having the above-mentioned anionic substituent in the above ratio is preferable in that it can be ultrafine due to the electrostatic repulsion effect. Moreover, the fine fibrous cellulose having an ionic substituent does not aggregate in water due to the electrostatic repulsion effect and can stably exhibit a thickening action. Furthermore, reaggregation after the fine fibrous cellulose is decomposed can be effectively suppressed.

<General 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 of the chemical treatment include acid treatment, ozone treatment, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment, enzyme treatment, and covalent bond with a functional group in cellulose or fiber raw material. Treatment with a compound capable of forming. In addition, it is preferable that the fine fibrous cellulose used by this invention has a phosphoric acid group or a carboxyl group. For this reason, as a chemical treatment method, treatment with a compound having a phosphate group or a carboxyl group and / or a salt thereof is preferably performed.

  As an example of the acid treatment, the method described in Otto van den Berg; Jeffrey R. Capadona; Christoph Weder; Biomacromolecules 2007, 8, 1353-1357. Specifically, the fine fibrous cellulose is hydrolyzed with sulfuric acid, hydrochloric acid, or the like. Those produced by high-concentration acid treatment are almost decomposed in non-crystalline regions and have short fibers (also called cellulose nanocrystals), which are also included in fine fibrous cellulose.

  As an example of the ozone treatment, a method described in JP 2010-254726 A can be exemplified, but it is not particularly limited. Specifically, after the fiber is treated with ozone, it is dispersed in water, and the resulting aqueous suspension of the fiber is pulverized.

  An example of TEMPO oxidation includes the method described in Saito T & al. Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose. Biomacromolecules 2006, 7 (6), 1687-91. Specifically, after the fiber is subjected to TEMPO oxidation treatment, it is dispersed in water, and the aqueous suspension of the obtained fiber is pulverized.

  As an example of the enzyme treatment, the method described in WO2013 / 176033 (all contents described in WO2013 / 176033 shall be cited in the present specification) can be mentioned, but is not particularly limited. . Specifically, the fiber raw material is treated with an enzyme at least under a condition where the ratio of the enzyme EG activity to the CBHI activity is 0.06 or more.

  The treatment with a compound capable of forming a covalent bond with a functional group in cellulose or a fiber raw material is described in International Publication WO2013 / 073652 (PCT / JP2012 / 079743) “an oxo acid containing a phosphorus atom in its structure, And a method using at least one compound selected from polyoxoacids or salts thereof.

<Introduction of anionic substituent>
The fine fibrous cellulose preferably has an anionic substituent. Among these, the anionic group is preferably at least one selected from a phosphate group, a carboxyl group, and a sulfone group, more preferably at least one selected from a phosphate group and a carboxyl group, Particularly preferred is an acid group.

<Introduced amount of substituent>
The amount of the anionic substituent introduced is not particularly limited, but is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, per 1 g (mass) of fine fibrous cellulose. / G or more is more preferable, and 0.5 mmol / g or more is particularly preferable. The amount of anionic substituent introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, further preferably 2.5 mmol / g or less. Particularly preferred is 0 mmol / g or less. By making the introduction amount of the anionic substituent within the above range, the fiber raw material can be easily miniaturized, and the stability of the fine fibrous cellulose can be enhanced. Moreover, the fine fibrous cellulose having an ionic substituent does not aggregate in water due to the electrostatic repulsion effect and can stably exhibit a thickening action. Furthermore, reaggregation after the fine fibrous cellulose is decomposed can be effectively suppressed.

<Introduction of phosphate group>
In the present invention, the fine fibrous cellulose preferably has a phosphate group or a substituent derived from the phosphate group.

<Phosphate group introduction process>
The phosphoric acid group introduction step can be performed by reacting a fiber raw material containing cellulose with at least one selected from a compound having a phosphate group and a salt thereof (hereinafter referred to as “compound A”). . Such a compound A may be mixed in a powder or aqueous solution with a dry or wet fiber raw material. As another example, a powder of compound A or an aqueous solution may be added to the fiber raw material slurry.

  The phosphoric acid group introducing step can be performed by reacting at least one (compound A) selected from a compound having a phosphoric acid group and a salt thereof with a fiber raw material containing cellulose. This reaction may be carried out in the presence of at least one selected from urea and derivatives thereof (hereinafter referred to as “compound B”).

  As an example of a method for causing compound A to act on a fiber raw material in the presence of compound B, a method of mixing powder or an aqueous solution of compound A and compound B with a dry or wet fiber raw material can be mentioned. Another example is a method in which powders and aqueous solutions of Compound A and Compound B are added to the fiber raw material slurry. Among these, since the uniformity of the reaction is high, a method of adding an aqueous solution of Compound A and Compound B to a dry fiber material, or a powder or an aqueous solution of Compound A and Compound B to a wet fiber material The method is preferred. Moreover, the compound A and the compound B may be added simultaneously, or may be added separately. Moreover, you may add the compound A and the compound B first used for reaction as aqueous solution, and remove an excess chemical | medical solution by pressing. The form of the fiber raw material is preferably cotton or thin sheet, but is not particularly limited.

Compound A used in this embodiment is at least one selected from a compound having a phosphate group and a salt thereof.
Examples of the compound having a phosphate group include, but are not limited to, phosphoric acid, lithium salt of phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, ammonium salt of phosphoric acid, and the like. Examples of the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate. Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate. Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.

  Among these, phosphoric acid, sodium phosphate, from the viewpoint of high phosphate group introduction efficiency, easy defibration efficiency in the defibration process described later, low cost, and easy industrial application. A salt, or a potassium salt of phosphoric acid or an ammonium salt of phosphoric acid is preferable. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferable.

  In addition, compound A is preferably used as an aqueous solution because the uniformity of the reaction is increased and the efficiency of introduction of phosphate groups is increased. The pH of the aqueous solution of Compound A is not particularly limited, but is preferably 7 or less because the efficiency of introduction of phosphate groups is increased, and more preferably 3 or more and 7 or less from the viewpoint of suppressing hydrolysis of pulp fibers. The pH of the aqueous solution of Compound A may be adjusted by, for example, using a phosphoric acid group-containing compound that exhibits acidity and an alkalinity, and changing the amount ratio thereof. You may adjust pH of the aqueous solution of the compound A by adding an inorganic alkali or an organic alkali to the thing which shows acidity among the compounds which have a phosphoric acid group.

  The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material is preferably 0.5% by mass or more and 100% by mass or less. More preferably, they are more than 50 mass% and most preferably 2 mass% or more and 30 mass% or less. If the amount of phosphorus atoms added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. When the addition amount of phosphorus atoms with respect to the fiber raw material exceeds 100% by mass, the effect of improving the yield reaches a peak and the cost of the compound A to be used increases. On the other hand, a yield can be raised by making the addition amount of the phosphorus atom with respect to a fiber raw material more than the following lower limit.

  Examples of the compound B used in this embodiment include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, and hydantoin. Among these, urea is preferable because it is easy to handle at low cost and easily forms a hydrogen bond with a fiber raw material having a hydroxyl group.

  Compound B is preferably used as an aqueous solution in the same manner as Compound A. Moreover, since the uniformity of reaction increases, it is preferable to use the aqueous solution in which both compound A and compound B are dissolved. The amount of compound B added to the fiber raw material is preferably 1% by mass or more and 300% by mass or less.

  In addition to Compound A and Compound B, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, and the like. Among these, triethylamine is known to work as a good reaction catalyst.

  In the phosphoric acid group introduction step, it is preferable to perform a heat treatment. As the heat treatment temperature, it is preferable to select a temperature at which a phosphate group can be efficiently introduced while suppressing thermal decomposition and hydrolysis reaction of the fiber. Specifically, it is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 150 ° C. or higher and 200 ° C. or lower. Moreover, you may use a vacuum dryer, an infrared heating apparatus, and a microwave heating apparatus for a heating.

  During the heat treatment, while water is contained in the fiber raw material slurry to which compound A is added, if the time for allowing the fiber raw material to stand still becomes long, the compound A dissolved with water molecules moves to the fiber raw material surface with drying. To do. Therefore, the concentration of the compound A in the fiber raw material may be uneven, and the introduction of phosphate groups on the fiber surface may not proceed uniformly. In order to suppress the occurrence of unevenness in concentration of Compound A in the fiber material due to drying, a very thin sheet-like fiber material is used, or the fiber material and Compound A are kneaded or stirred with a kneader or the like and dried by heating or reduced pressure. The method should be taken.

  The heating device used for the heat treatment is preferably a device that can always discharge the moisture retained by the slurry and the moisture generated by the addition reaction of the fibers such as phosphate groups to the hydroxyl group of the fiber, such as a blower oven. Etc. are preferred. If water in the system is always discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the esterification, can be suppressed, and the acid hydrolysis of the sugar chain in the fiber can also be suppressed. A fine fiber having a high axial ratio can be obtained.

  The heat treatment time is also affected by the heating temperature, but it is preferably 1 second or more and 300 minutes or less, preferably 1 second or more and 1000 seconds or less after moisture is substantially removed from the fiber raw material slurry. Preferably, it is 10 seconds or more and 800 seconds or less. In the present invention, the amount of phosphate groups introduced can be within a preferred range by setting the heating temperature and the heating time to appropriate ranges.

<Introduction amount of phosphate group>
The amount of phosphate group introduced is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and 0.3 mmol / g or more per 1 g (mass) of fine fibrous cellulose. More preferably, it is particularly preferably 0.5 mmol / g or more. The amount of phosphate group introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, further preferably 2.5 mmol / g or less, and 2.0 mmol / G or less is particularly preferable. By making the introduction amount of the phosphate group within the above range, the fiber raw material can be easily refined, and the stability of the fine fibrous cellulose can be enhanced. Moreover, the fine fibrous cellulose which has a phosphate group does not aggregate in water by an electrostatic repulsion effect, and can exhibit a thickening effect stably. Furthermore, reaggregation after the fine fibrous cellulose is decomposed can be effectively suppressed.

  The amount of phosphate group introduced into the fiber material can be measured by a conductivity titration method. Specifically, by performing the defibration process step, after treating the resulting fine fibrous cellulose-containing slurry with an ion exchange resin, by determining the change in electrical conductivity while adding an aqueous sodium hydroxide solution, The amount introduced can be measured.

  In conductivity titration, when alkali is added, the curve shown in FIG. 1 is given. Initially, the electrical conductivity rapidly decreases (hereinafter referred to as “first region”). Thereafter, the conductivity starts to increase slightly (hereinafter referred to as “second region”). Thereafter, the conductivity increment increases (hereinafter referred to as “third region”). That is, three areas appear. Among these, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Will be equal. When the phosphoric acid group undergoes condensation, apparently weakly acidic groups are lost, and the amount of alkali required in the second region is reduced compared to the amount of alkali required in the first region. On the other hand, the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation, so that the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituent introduced (or the amount of substituents) is simply When said, it represents the amount of strongly acidic group. That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 is divided by the solid content (g) in the titration target slurry to obtain the substituent introduction amount (mmol / g).

  The phosphate group introduction step may be performed at least once, but may be repeated a plurality of times. In this case, more phosphoric acid groups are introduced, which is preferable.

<Introduction of carboxyl group>
In the present invention, when the fine fibrous cellulose has a carboxyl group, it is possible to introduce a carboxyl group by using a compound having a group derived from a carboxylic acid in the above-described <phosphate group introduction step>. it can.

  The compound having a carboxyl group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. . Of these, maleic acid is preferably used as the compound having a carboxyl group.

  The acid anhydride of the compound having a carboxyl group is not particularly limited, but examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. It is done. Of these, maleic anhydride is preferably used.

  Although it does not specifically limit as a derivative of the compound which has a carboxyl group, The derivative of the acid anhydride of the compound which has a carboxyl group and the acid anhydride imidation of a compound which has a carboxyl group are mentioned. Although it does not specifically limit as an acid anhydride imidation thing of a compound which has a carboxyl group, Imidation thing of dicarboxylic acid compounds, such as maleimide, succinic acid imide, and phthalic acid imide, is mentioned.

  The acid anhydride derivative of the compound having a carboxyl group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxyl group, such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride, etc. are substituted (for example, alkyl group, phenyl group, etc. ) Are substituted.

<Introduction amount of carboxyl group>
The amount of carboxyl groups introduced is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and 0.3 mmol / g or more per 1 g (mass) of fine fibrous cellulose. Is more preferably 0.5 mmol / g or more. The amount of carboxyl group introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, further preferably 2.5 mmol / g or less, and 2.0 mmol / g. It is particularly preferred that it is g or less. By making the introduction amount of the carboxyl group within the above range, the fiber raw material can be easily refined, and the stability of the fine fibrous cellulose can be enhanced. Moreover, the fine fibrous cellulose which has a carboxyl group does not aggregate in water by an electrostatic repulsion effect, and can exhibit a thickening effect stably. Furthermore, reaggregation after the fine fibrous cellulose is decomposed can be effectively suppressed.

The amount of carboxyl group introduced into the fiber material can be measured by a conductivity titration method. Specifically, by performing the defibration process step, after treating the resulting fine fibrous cellulose-containing slurry with an ion exchange resin, by determining the change in electrical conductivity while adding an aqueous sodium hydroxide solution, The amount introduced can be measured.
In conductivity titration, when an alkali is added, the curve shown in FIG. 2 is given. The alkali amount (mmol) required in the first region of the curve shown in FIG. 2 is divided by the solid content (g) in the slurry to be titrated to obtain the substituent introduction amount (mmol / g).

<Cationic substituent introduction>
In this embodiment, a cationic substituent may be introduced into the fine fibrous cellulose as an ionic substituent. For example, a cationic substituent can be introduced into the fiber raw material by adding a cationizing agent and an alkali compound to the fiber raw material and causing the fiber raw material to react.
As the cationizing agent, one having a quaternary ammonium group and a group that reacts with a hydroxyl group of cellulose can be used. Examples of the group that reacts with the hydroxyl 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 alkali compound contributes to the promotion of the cationization reaction. 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 phosphates, etc. Organic alkali compounds such as ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates, phosphates, etc. It may be. The introduction amount of the cationic substituent can be measured using, for example, elemental analysis.

<Alkali treatment>
In the case of producing fine fibrous cellulose, alkali treatment can be performed between the substituent introduction step and the defibration treatment step described later. Although it does not specifically limit as a method of an alkali treatment, For example, the method of immersing a phosphate group introduction | transduction fiber in an alkaline solution is mentioned.
The alkali compound contained in the alkali solution is not particularly limited, but may be an inorganic alkali compound or an organic alkali compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (polar organic solvent such as water or alcohol), and more preferably an aqueous solvent containing at least water.
Of the alkaline solutions, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is particularly preferred because of its high versatility.

Although the temperature of the alkali solution in an alkali treatment process is not specifically limited, 5 to 80 degreeC is preferable and 10 to 60 degreeC is more preferable.
The immersion time in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or longer and 30 minutes or shorter, and more preferably 10 minutes or longer and 20 minutes or shorter.
Although the usage-amount of the alkaline solution in an alkali treatment is not specifically limited, It is preferable that it is 100 mass% or more and 100,000 mass% or less with respect to the absolute dry mass of a phosphate group introduction | transduction fiber, and is 1000 mass% or more and 10000 mass% or less. It is more preferable.

  In order to reduce the amount of alkaline solution used in the alkali treatment step, the phosphate group-introduced fiber may be washed with water or an organic solvent before the alkali treatment step. After the alkali treatment, in order to improve the handleability, it is preferable to wash the alkali-treated phosphate group-introduced fiber with water or an organic solvent before the defibrating treatment step.

<Defibration processing>
The ionic substituent-introduced fiber is defibrated in the defibrating process. In the defibrating process, the fiber is usually defibrated using a defibrating apparatus to obtain a fine fibrous cellulose-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 treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high 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, a polar organic solvent can be used in addition to water. Preferable polar organic solvents include alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like, but are not particularly limited. 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.

  In the present invention, the fibrillation treatment may be performed after the fine fibrous cellulose is concentrated and dried. In this case, the concentration and drying methods are not particularly limited, and examples thereof include a method of adding a concentrating agent to a slurry containing fine fibrous cellulose, a generally used dehydrator, a press, and a method using a dryer. Moreover, a well-known method, for example, the method described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used. Further, the concentrated fine fibrous cellulose may be formed into a sheet. The sheet can be pulverized to perform a defibrating process.

  The equipment used for pulverization of fine fibrous cellulose includes high-speed fibrillators, grinders (stone mill type pulverizers), high-pressure homogenizers, ultra-high pressure homogenizers, high-pressure collision type pulverizers, ball mills, bead mills, disk type refiners, and conicals. An apparatus for wet pulverization such as a refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, a beater, and the like can be used, but is not particularly limited.

  The fine fibrous cellulose having a phosphate group obtained by the above-described method is a fine fibrous cellulose-containing slurry, and may be diluted with water so as to have a desired concentration.

<Ionic water-soluble polymer>
The underground layer treatment composition of the present invention may further contain an ionic water-soluble polymer, and both the ionic water-soluble polymer and the nonionic water-soluble polymer are contained in the underground layer treatment composition. The case where it contains can be mention | raise | lifted as an example of a preferable aspect. A composition for treating an underground layer containing an ionic water-soluble polymer can exhibit more excellent salt resistance. For this reason, salt water can be used in order to prepare the fluid for underground processing, and salt water can be utilized when salt water is easy to be obtained in the environment where processing is performed.

  Examples of the ionic water-soluble polymer include natural water-soluble polymer derivatives such as xanthan gum and alginic acid, water-soluble celluloses such as carboxymethyl cellulose, starches such as cationized starch and oxidized starch. It is not limited. Among these, xanthan gum is preferably used as the ionic water-soluble polymer.

  The content of the ionic water-soluble polymer in the underground layer treatment composition is preferably 1 part by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the fine fibrous cellulose. The content of the ionic water-soluble polymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and more preferably 5 parts by mass or more with respect to 100 parts by mass of the fine fibrous cellulose. Further preferred. Further, the content of the ionic water-soluble polymer is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and further preferably 150 parts by mass or less.

(Production method of composition for underground layer treatment)
It is preferable that the manufacturing process of the composition for underground layer treatment of this invention includes the process of obtaining a fine fibrous cellulose, and the process of mixing a fine fibrous cellulose and a nonionic water-soluble polymer. The fine fibrous cellulose is preferably a slurry, and is preferably mixed with a nonionic water-soluble polymer in water.

  The method for mixing the fine fibrous cellulose and the nonionic water-soluble polymer is not particularly limited, and a known stirring method can be employed.

  The composition for underground layer treatment can be in various forms such as a solid, a slurry, a dried product, and a concentrate. Since it is dispersed in an aqueous dispersion medium when used, it may be processed to facilitate dispersion. From the viewpoint of transportability and handling at the work site, it is desirable to be provided in the form of a concentrate or a dried product.

  When concentrating or drying, 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.

  Examples of the concentrating agent include acids, alkalis, polyvalent metal salts, cationic surfactants, anionic surfactants, cationic polymer flocculants, anionic polymer flocculants, and organic solvents. More specifically, aluminum sulfate (sulfate band), polyaluminum chloride, calcium chloride, aluminum chloride, magnesium chloride, potassium chloride, calcium sulfate, magnesium sulfate, potassium sulfate, lithium phosphate, potassium phosphate, trisodium phosphate, phosphorus Disodium oxyhydrogen, inorganic acids (sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc.), organic acids (formic acid, acetic acid, citric acid, malic acid, lactic acid, adipic acid, sebacic acid, stearic acid, maleic acid, succinic acid, tartaric acid , Fumaric acid, gluconic acid, etc.), cationic surfactant (alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, acylaminoethyldiethylammonium salt, acylaminoethyldiethylamine salt, alkylamidopropiate Dimethylbenzylammonium salt, alkylpyridinium salt, alkylpyridinium sulfate, stearamide methylpyridinium salt, alkylquinolinium salt, alkylisoquinolinium salt, fatty acid polyethylene polyamide, acylaminoethylpyridinium salt, acylcoraminoformylmethylpyridinium salt Quaternary ammonium salts such as stearooxymethylpyridinium salt, fatty acid triethanolamine, fatty acid triethanolamine formate, trioxyethylene fatty acid triethanolamine, cetyloxymethylpyridinium salt, p-isooctylphenoxyethoxyethyldimethylbenzyl Ester bond amine such as ammonium salt, ether bond quaternary ammonium salt, alkylimidazoline, 1-hydroxyethyl-2-alkyl Complex amines such as loumidazoline, 1-acetylaminoethyl-2-alkylimidazoline, 2-alkyl-4-methyl-4-hydroxymethyloxazoline, polyoxyethylene alkylamine, N-alkylpropylenediamine, N-alkylpolyethylenepolyamine , N-alkyl polyethylene polyamine dimethyl sulfate, amine derivatives such as alkyl biguanides, long chain amine oxides), cationic polymer flocculants (acrylamide and dialkylaminoalkyl (meth) acrylates, dialkylaminoalkyl (meth) acrylamides or these) Copolymers with cationic monomers such as salts or quaternized compounds, or homopolymers or copolymers of these cationic monomers), alkalis (lithium hydroxide, sodium hydroxide, hydroxide) Lithium, calcium hydroxide, lithium carbonate, lithium bicarbonate, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, Propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxy , Benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4- Minopyridine, etc.), anionic surfactant (sodium oleate, potassium oleate, sodium laurate, sodium todecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, polyoxy Sodium ethylene alkyl allyl ether sulfate, sodium polyoxyethylene dialkyl sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, etc.), anionic polymer flocculants (polyacrylic acid, sodium polyacrylate) , Copolymers of (meth) acrylic acid or alkali metal salts thereof and (meth) acrylamide, hydrolysates of poly (meth) acrylamide A copolymer of vinyl sulfonic acids such as acryloylamino-2-methylpropyl sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid or a salt thereof and (meth) acrylic acid or an alkali metal salt thereof and (meth) acrylamide, Carboxymethyl cellulose, carboxymethyl starch, sodium alginate and the like).

  Examples of the organic solvent are not particularly limited, but those having miscibility with water are preferable, and those having polarity are more preferable. Preferable examples of the organic solvent having polarity include alcohols, dioxanes (1,2-dioxane, 1,3-dioxane, 1,4-dioxane), tetrahydrofuran (THF) and the like, but are not particularly limited. Specific examples of alcohols are methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol, and the like. Preferable examples of organic solvents having other polarities include ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), and the like. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of ethers include diethyl ether and tetrahydrofuran (THF). When selecting an organic solvent, a solubility parameter value (SP value) may be considered. Since it is empirically known that the smaller the difference between the SP values of the two components, the greater the solubility, so from the viewpoint of good miscibility with water, an organic solvent having an SP value close to water is used. You can choose. One type of these thickeners may be used, or two or more types may be used in combination.

(Underground fluid)
The present invention also relates to an underground layer treatment fluid containing fine fibrous cellulose having a fiber width of 1000 nm or less, a nonionic water-soluble polymer, and a fluid. The underground layer processing fluid of the present invention contains the above-described underground layer processing composition and fluid. The fluid contained in the underground layer treatment fluid may be added separately from the underground layer treatment composition, or may be a fluid contained in the underground layer treatment composition. The fluid in the underground treatment fluid of the present invention is at least one selected from the fluid contained in the underground treatment composition and the newly added fluid.

  An example of the fluid contained in the underground layer treatment fluid is water. In addition to pure, the water includes salt water represented by seawater. As the fluid, an organic solvent or a mixture of water and an organic solvent can also be used. Examples of the organic solvent include alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMAc), but are not particularly limited. 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). As the fluid, water or salt water is preferably used, and water is more preferably used.

  The content of fine fibrous cellulose in the underground layer processing fluid is preferably 0.05% by mass or more and more preferably 0.1% by mass or more with respect to the total mass of the underground layer processing fluid. Preferably, it is 0.15 mass% or more. The content of fine fibrous cellulose is preferably 1.0% by mass or less, more preferably 0.6% by mass or less, and further preferably 0.4% by mass or less. The content of fine fibrous cellulose in the underground layer treatment fluid can be appropriately adjusted according to the content of the nonionic water-soluble polymer contained in the underground layer treatment fluid.

  The content of the nonionic water-soluble polymer in the underground layer processing fluid is preferably 0.001% by mass or more and 0.005% by mass or more with respect to the total mass of the underground layer processing fluid. It is more preferable that the content is 0.01% by mass or more. The content of the nonionic water-soluble polymer is preferably 0.5% by mass or less, more preferably 0.4% by mass or less, and further preferably 0.3% by mass or less. preferable. In addition, content of the fine fibrous cellulose in the underground layer processing fluid can be appropriately adjusted according to the content of the fine fibrous cellulose contained in the underground layer processing fluid.

  The underground layer treatment fluid preferably further contains a decomposition agent. Here, the decomposing agent has a property of decomposing fine fibrous cellulose. The decomposing agent is preferably one capable of cleaving the cellulose chain of fine fibrous cellulose, and examples of the decomposing agent include an oxidizing agent, an enzyme, and an acid. Among these, the decomposing agent is preferably an oxidizing agent, and examples of the oxidizing agent include ammonium peroxodisulfate, potassium peroxodisulfate, and sodium bromate.

  It is preferable that the decomposing agent does not exhibit its resolution yet at the stage of preparing the underground layer treatment fluid, but exhibits its resolution after flowing into the underground layer. By exhibiting the resolution in this way, the underground layer processing fluid has a sufficiently high viscosity before the underground layer processing fluid flows into the underground layer. However, the viscosity of the underground layer processing fluid is lowered by the decomposition of the fine fibrous cellulose after the underground layer processing fluid flows into the underground layer. The behavior of the viscosity by such a decomposing agent plays an important role in order to cause the granular material described later to settle at the intended location of the underground layer.

  In order to control the resolution of the decomposing agent, for example, the decomposing agent is sealed in a capsule or the like and designed so that the capsule dissolves at a certain temperature or after a certain period of time. It is good also as an aspect discharged | emitted by. Alternatively, after the underground layer treatment fluid is allowed to flow into the underground layer, the decomposition agent may be injected into a predetermined place through a tube or the like.

  The content of the decomposing agent varies depending on the type of the dispersant used and the content of the fine fibrous cellulose contained. For example, 0.01 mass with respect to the total mass of the underground layer treatment fluid % To 1% by mass is preferable. By setting the content of the decomposing agent within the above range, the fine fibrous cellulose can be decomposed when necessary, and the viscosity of the underground layer treatment fluid can be reduced.

  The underground layer treatment fluid may further include a granular material having an average particle diameter of 0.1 mm or more and 10 mm or less. An example of such a granular material is proppant. Propant is a solid having an average particle size of about 0.5 mm. Propant is mainly filled in cracks in the underground shale layer (collecting layer) when recovering natural resources such as shale gas and shale oil. Propant forms a natural resource channel (oil and gas passage) because natural resources flow out of the cracks in the shale layer. Examples of proppants include granular materials made of sand, glass beads, ceramic particles, resin-coated sand, and the like.

  In addition, the average particle diameter of the said granular material may be measured after enlarging by microscope observation etc., and may be measured visually. When the granular material is not spherical, the average particle diameter is calculated on the assumption that the granular material is spherical with the same volume as the granular material.

  Although content of a granular material changes also with the state of the underground layer which is a process target, it is preferable that 1 mass% or more and 20 mass% or less are contained with respect to the total mass of the fluid for underground formation processes, for example. By setting the content of the granular material within the above range, the underground shale layer (collecting layer) is appropriately filled with cracks.

  The underground layer treatment fluid may further contain an ionic water-soluble polymer. Also, weighting materials, viscosity modifiers, dispersants, flocculants, anti-mudging agents, dehydration regulators, pH control agents, friction reducers, hydration expansion control agents, emulsifiers, surfactants, biocides, antifoaming Agents, scale inhibitors, corrosion inhibitors, temperature stabilizers, resin coating agents, salts and the like. The component to be added is not limited to one type but may be two or more types.

  The viscosity of the underground layer treatment fluid is preferably 3000 mPa · s or more, more preferably 3500 mPa · s or more, and further preferably 4000 mPa · s or more. Here, the viscosity of the underground layer treatment fluid is a value measured at a rotational temperature of 3 rpm and a measurement time of 3 minutes at a liquid temperature of 25 ° C. using a B-type viscometer. When measuring the viscosity of the underground layer processing fluid, the measurement is performed after passing a 355 μm mesh and removing coarse solids.

  Further, ammonium peroxodisulfate was added to the underground layer treatment fluid so as to be 0.06% by mass (2.63 mmol / L), and after standing at 70 ° C. for 6 hours, the viscosity of the supernatant liquid was 800 mPa · s. Is preferably 700 mPa · s or less, and more preferably 650 mPa · s or less. The viscosity of the supernatant is a value measured at a liquid temperature of 25 ° C. using a B-type viscometer at a rotation speed of 3 rpm and a measurement time of 3 minutes.

  In the present invention, since the underground layer treatment fluid contains a nonionic water-soluble polymer, the underground layer treatment after adding a decomposing agent such as ammonium peroxodisulfate and subdividing the fine fibrous cellulose. The viscosity of the working fluid is maintained for a long time with a low state. That is, the nonionic water-soluble polymer suppresses the formation of a gel-like aggregate by aggregation of fine fibrous cellulose decomposed by the decomposing agent. For this reason, the underground layer processing fluid is maintained in a low-viscosity state after processing, and is easy to recover.

  The underground layer processing fluid of the present invention is used for processing the underground layer. Here, the underground layer treatment is, for example, cementing, well survey, logging work, recovery of natural resources, well stimulation, water mud, oil mud, well finishing using chemical fluid or brine, infiltration Fracturing using high-pressure fracturing fluid to make a passage (break, fracture) in a tight underground layer with low rate, well repair, waste mine treatment, etc. Subsurface treatment fluids include fracturing fluid, mud, cementing fluid, well control fluid, well kill fluid, acid fracturing fluid, acid diverting fluid fluid, stimulation fluid, sand control fluid, completion fluid, wellbore consolidation fluid, remediation treatment fluid, spacer fluid fluid, drilling fluid, frac-packing fluid, water conformance fluid, gravel packing fluid, and the like.

  Among them, the underground layer processing fluid of the present invention is preferably a fracturing fluid, and particularly preferably a fracturing fluid used for underground layer processing for the purpose of recovering natural resources. Here, natural resources refer to all mineral hydrocarbons in the solid, solid, liquid and gaseous. Specifically, natural resources include liquid petroleum (oil) and gaseous natural gas, which are general categories. Natural resources include conventional oil and natural gas, as well as tight sand gas, shale oil, tight oil, heavy oil, super heavy oil, shale gas, coal seam gas, bitumen, heavy oil, oil sand, oil Includes shale and methane hydrate. The underground layer treatment fluid of the present invention is particularly preferably a fracturing fluid used for underground layer treatment for the purpose of recovering shale oil or shale gas.

(Manufacturing method of fluid for underground layer treatment)
The production process of the underground layer treatment fluid of the present invention includes a step of mixing a fine fibrous cellulose having a fiber width of 1000 nm or less and a nonionic water-soluble polymer to obtain a composition for underground layer treatment, and a underground layer treatment. Mixing the composition with the fluid. In the manufacturing process of the underground layer treatment fluid of the present invention, it is preferable to further include a step of adding a decomposition agent after the step of obtaining the underground layer processing composition. Moreover, it is preferable to further include the process of adding the granular material whose average particle diameter is 0.1 mm or more and 10 mm or less after the process of obtaining the composition for underground layer treatment.

  The step of adding a decomposing agent is preferably provided immediately before processing the underground layer. This is because it is preferable that the decomposing agent does not yet exhibit its resolution at the stage where the underground layer treatment fluid is prepared, but exhibits its resolution after flowing into the underground layer. By exhibiting the resolution in this way, the underground layer processing fluid has a sufficiently high viscosity before the underground layer processing fluid flows into the underground layer. However, the viscosity of the underground layer processing fluid is lowered by the decomposition of the fine fibrous cellulose after the underground layer processing fluid flows into the underground layer.

  The step of adding a decomposing agent and the step of adding a granular material having an average particle diameter of 0.1 mm or more and 10 mm or less are preferably provided after the step of mixing the underground treatment composition and the fluid. It may be provided simultaneously with the step of mixing the composition for use and the fluid. Moreover, it is good also as adding a decomposition agent and a granular material, after mixing the composition for underground layer processing, and making it flow into an underground layer. That is, the underground processing fluid of the present invention may be a fluid for adding a decomposition agent and particulate matter.

(Underground treatment method)
The present invention also relates to a method for treating an underground layer including a step of causing the above-described underground layer processing fluid to flow into the underground layer. The method for treating an underground layer of the present invention recovers a treated fluid containing at least fine fibrous cellulose, a nonionic water-soluble polymer, and a fluid after the step of flowing the underground layer treatment fluid into the underground layer. Preferably, the method further includes the step of: Furthermore, in the underground layer processing method of the present invention, the granular material having an average particle size of 0.1 mm or more and 10 mm or less is provided between the step of flowing the underground processing fluid into the underground layer and the step of recovering the processed fluid. It is preferable to include a step of settling.

  In the step of flowing the underground layer processing fluid into the underground layer, the underground layer processing fluid is poured into a well provided in the underground layer by a high-pressure pump or the like. Then, it is preferable to provide the process of settling the granular material whose average particle diameter is 0.1 mm or more and 10 mm or less. In the step of settling the particulate matter, a high pressure is applied to the well to create a crack in the sampling layer, and a support material such as a particulate matter having an average particle size of 0.1 mm to 10 mm is filled therein. The particulates prevent crack plugging and form a very permeable channel (oil gas path) in the collection layer.

In the step of allowing the underground layer processing fluid to flow into the underground layer, it is preferable that the oxidizing agent and the particulate matter are uniformly dispersed in the underground layer processing fluid. Thereby, decomposition | disassembly of the fine fibrous cellulose contained in the fluid for underground layer processing can be accelerated | stimulated uniformly, and also a granular material can be uniformly filled into the crack in a collection layer.
It is preferable that the step of settling the granular material having an average particle size of 0.1 mm or more and 10 mm or less includes a step of decomposing fine fibrous cellulose contained in the underground layer treatment fluid. For example, it is preferable to include a step of cleaving a cellulose chain of fine fibrous cellulose by acting a decomposing agent. That is, in the step of settling the granular material having an average particle size of 0.1 mm or more and 10 mm or less, it is preferable to reduce the viscosity of the underground layer processing fluid, and thereby, it is uniformly dispersed in the underground layer processing fluid. The granular material settles and the granular material fills the cracks in the collection layer.

  After the granular material settles, it is preferable to provide a step of collecting the treated fluid. The post-treatment fluid includes at least a fine fibrous cellulose, a nonionic water-soluble polymer, and a fluid. In addition, the post-treatment fluid may contain particulate matter remaining without settling, unreacted oxidizing agent, and the like. In the step of recovering the processed fluid, the processed fluid with reduced viscosity is recovered using a suction force of a pump or the like. In the present invention, since the underground layer treatment fluid contains a nonionic water-soluble polymer, the viscosity of the treated fluid whose viscosity has been reduced by decomposing fine fibrous cellulose remains low. Is done. In addition, the nonionic water-soluble polymer also suppresses the formation of a gel-like aggregate by re-aggregation of the fine fibrous cellulose after decomposition. For this reason, recovery of the fluid after processing can be performed smoothly.

  After recovering the treated fluid, natural resources flow out of the crack. Since the natural resources that have flowed out from the crack exist in the well after the treated fluid is collected, the purpose of the underground layer treatment is achieved by collecting it.

(Other aspects)
The present invention may be an underground layer processing kit having the above-described underground layer processing composition, a decomposing agent, and a granular material having an average particle diameter of 0.1 mm to 10 mm. In such an underground layer treatment kit, the underground layer treatment composition, the decomposing agent, and the granular material are contained in a separated state, and these may be mixed and used for underground layer treatment when necessary. Can do.

The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. In the following, Example 5 is to be read as Reference Example 5.

<Production Example 1>
A softwood kraft pulp with a dry mass of 100 parts by mass is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and compressed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea. Got. The obtained chemical solution-impregnated pulp was dried with a dryer at 105 ° C. to evaporate the moisture and pre-dried. Then, it heated for 10 minutes with the ventilation dryer set to 140 degreeC, the phosphate group was introduce | transduced into the cellulose in a pulp, and the phosphorylated pulp was obtained.

  The obtained phosphorylated pulp was fractionated by 100 g, and 10 L of ion-exchanged water was poured, stirred and dispersed uniformly, and then subjected to filtration and dehydration to obtain a dehydrated sheet, which was repeated twice. Next, the obtained dehydrated sheet was diluted with 10 L of ion-exchanged water, and a 1N sodium hydroxide aqueous solution was added little by little while stirring to obtain a pulp slurry having a pH of 12 or more and 13 or less. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then 10 L of ion exchange water was added. The step of stirring and dispersing uniformly, followed by filtration and dehydration to obtain a dehydrated sheet was repeated twice.

In the same manner as described above, the step of introducing a phosphate group and the step of filtration and dehydration were repeated for the obtained dehydrated sheet to obtain a dehydrated sheet of phosphorylated cellulose twice. An infrared absorption spectrum of the obtained dehydrated sheet was measured by FT-IR. As a result, absorption based on phosphate groups was observed at 1230 cm ⁻¹ or more and 1290 cm ⁻¹ or less, and addition of phosphate groups was confirmed. Therefore, the obtained dehydrated sheet (double-phosphorylated cellulose) was obtained by substituting some of the hydroxyl groups of cellulose with the functional group of the following structural formula (1).

In the formula, a, b, m and n each independently represent a natural number (where a = b × m). α ¹ , α ² ,..., α ⁿ and α ′ each independently represent R or OR. R represents a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. , Aromatic groups, and any of these derived groups. β is a monovalent or higher cation composed of an organic substance or an inorganic substance.

  Ion exchange water was added to the obtained twice phosphorylated cellulose to prepare a slurry having a solid content concentration of 2% by mass. This slurry was further treated three times at a pressure of 245 MPa with a wet atomization apparatus (manufactured by Sugino Machine Co., Ltd., an optimizer) to obtain fine fibrous cellulose 1. By X-ray diffraction, the fine fibrous cellulose maintained cellulose I type crystals.

<Production Example 2>
A fine fibrous cellulose 2 was obtained in the same manner as in Production Example 1 except that the phosphorylation and washing steps were performed three times. By X-ray diffraction, the fine fibrous cellulose maintained cellulose I type crystals.

<Production Example 3>
Undried softwood bleached kraft pulp equivalent to 100 parts by mass of dry mass, 1.25 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl), and 12.5 parts by mass of sodium bromide It was dispersed in 10,000 parts by weight of water. Subsequently, 13 mass% sodium hypochlorite aqueous solution was added so that the quantity of sodium hypochlorite might be 8.0 mmol with respect to 1.0 g of pulp, and reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 or more and 11 or less, and the reaction was regarded as complete when no change in pH was observed.

Thereafter, this pulp slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring 5000 parts by mass of ion exchange water, stirring and uniformly dispersing, and dehydrating by filtration to obtain a dehydrated sheet is repeated twice. It was. An infrared absorption spectrum of the obtained dehydrated sheet was measured by FT-IR. As a result, absorption based on a carboxyl group was observed at 1730 cm ⁻¹ , confirming the addition of a carboxyl group. Using this dehydrated sheet (TEMPO oxidized cellulose), fine fibrous cellulose was prepared.

  Ion exchange water was added to the obtained TEMPO oxidized cellulose to prepare a slurry having a solid content concentration of 2% by mass. This slurry was further processed three times at a pressure of 245 MPa with a wet atomization apparatus (manufactured by Sugino Machine Co., Ltd., an optimizer) to obtain fine fibrous cellulose 3. By X-ray diffraction, the fine fibrous cellulose maintained cellulose I type crystals.

<Production Example 4>
After mixing 100 parts by weight of dried softwood bleached kraft pulp and 50 parts by weight of maleic anhydride, the mixture was filled in an autoclave and treated at 150 ° C. for 2 hours. Next, the pulp treated with maleic anhydride was washed with 500 mL of water three times, and then ion-exchanged water was added to prepare 490 mL of slurry. Next, while stirring the slurry, 10 mL of 4N aqueous sodium hydroxide solution was added little by little to adjust the pH of the slurry to 12 or more and 13 or less, and the pulp was alkali-treated. Thereafter, the pulp after alkali treatment was washed with water until the pH became 8 or less.

Thereafter, this pulp slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring 5000 parts by mass of ion exchange water, stirring and uniformly dispersing, and dehydrating by filtration to obtain a dehydrated sheet is repeated twice. It was. An infrared absorption spectrum of the obtained dehydrated sheet was measured by FT-IR. As a result, absorption based on a carboxyl group was observed between 1580 cm ^{−1 and} 1720 cm ⁻¹ , confirming the addition of maleic acid. Using this dehydrated sheet (maleic oxidized cellulose), fine fibrous cellulose was prepared.

  Ion exchange water was added to the resulting maleated cellulose to prepare a slurry having a solid content concentration of 2% by mass. This slurry was further treated three times at a pressure of 245 MPa with a wet atomization apparatus (manufactured by Sugino Machine, Optimizer) to obtain fine fibrous cellulose 4. By X-ray diffraction, the fine fibrous cellulose maintained cellulose I type crystals.

(Measurement of substituent amount)
The amount of substituents (substituent introduction amount) is the amount of phosphate groups or carboxyl groups introduced into the fiber material. The larger the value, the more phosphate groups or carboxyl groups are introduced. The amount of introduced substituents was measured by diluting the target fine fibrous cellulose with ion-exchanged water so that the solid content concentration was 0.2% by mass, and then treating with ion-exchange resin and titration with alkali. In the treatment with an ion exchange resin, a 1/10 amount of strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) is added to a fibrous cellulose-containing slurry having a solid content concentration of 0.2% by mass. In addition, it was shaken for 1 hour. Thereafter, the mixture was poured onto a mesh having an opening of 90 μm to separate the resin and the slurry. In titration using an alkali, a change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after ion exchange. That is, the alkali amount (mmol) required in the first region of the curves shown in FIG. 1 (phosphate group) and FIG. 2 (carboxyl group) is divided by the solid content (g) in the titration target slurry, The amount of substituent introduced (mmol / g). The calculated results are shown in Table 1 below.

In addition, the fiber width of each fine fibrous cellulose was measured by the following method.
The supernatant of the fibrous cellulose-containing slurry was diluted with water to a concentration of 0.01% by mass or more and 0.1% by mass or less and dropped onto a hydrophilic carbon grid membrane. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.). It was confirmed that the fine fibrous celluloses 1 to 4 were fine fibrous cellulose having a width of about 4 nm.

<Example 1>
The fine fibrous cellulose 1 was added to ion-exchanged water so that the solid content concentration was 0.2% by mass and the final concentration of guar gum was 0.02% by mass. Using a disperser, the mixture was stirred at 1500 rpm for 5 minutes to prepare 120 g of a dispersion.

<Example 2>
In Example 1, except that the sample was prepared so that the solid content concentration of the fine fibrous cellulose 1 was 0.3% by mass and the final concentration of guar gum was 0.015% by mass, all the same methods as in Example 1 were used. 120 g of a dispersion was obtained.

<Example 3>
In Example 1, fine fibrous cellulose 2 was used instead of fine fibrous cellulose 1. Except that, 120 g of a dispersion was obtained in the same manner as in Example 1.

<Example 4>
In Example 2, fine fibrous cellulose 2 was used instead of fine fibrous cellulose 1. Except that, 120 g of a dispersion was obtained in the same manner as in Example 2.

<Example 5>
In Example 1, fine fibrous cellulose 3 was used instead of fine fibrous cellulose 1. Except that, 120 g of a dispersion was obtained in the same manner as in Example 1.

<Example 6>
In Example 1, fine fibrous cellulose 4 was used in place of the fine fibrous cellulose 1. Except that, 120 g of a dispersion was obtained in the same manner as in Example 1.

<Example 7>
In Example 1, xanthan gum was further added so as to be 0.2% by mass, and the dispersion was made in the same manner as in Example 1 except that the dispersion medium was changed from an ion exchange resin to a 2% by mass potassium chloride aqueous solution. 120 g was obtained.

<Example 8>
In Example 1, 120 g of a dispersion was obtained in the same manner as in Example 1 except that the sample was prepared so that the final concentration of guar gum was 0.1% by mass.

<Example 9>
In Example 1, a dispersion was prepared in the same manner as in Example 1 except that the sample was prepared so that the concentration of fine fibrous cellulose 1 was 0.35% by mass and the final concentration of guar gum was 0.0175% by mass. 120 g was obtained.

<Example 10>
In Example 1, a dispersion was prepared in the same manner as in Example 1 except that the sample was prepared so that the concentration of fine fibrous cellulose 1 was 0.1% by mass and the final concentration of guar gum was 0.3% by mass. 120 g was obtained.

<Example 11>
The fine fibrous cellulose 1 was added to ion-exchanged water so that the solid content concentration was 0.4 mass% and the final concentration of guar gum was 0.04 mass%. To 60 g of this cellulose suspension, 120 g of isopropyl alcohol was added, stirred at 1000 rpm, and concentrated to 1.2 g by filtration and compression. The concentrate thus obtained contained 20% by mass of fine fibrous cellulose. This concentrate was pulverized with a mixer to form a powder. Ion exchange water was added to the powdered pulverized product to make the total amount 120 g, and the mixture was stirred at 8000 rpm for 3 minutes using a disperser to obtain 120 g of a dispersion.

<Example 12>
The fine fibrous cellulose 1 was added to ion-exchanged water so that the solid content concentration was 0.4 mass%, the final concentration of guar gum was 0.04 mass%, and the final concentration of xanthan gum was 0.4 mass%. To 60 g of this cellulose suspension, 120 g of isopropyl alcohol was added, stirred at 1000 rpm, and concentrated to 1.2 g by filtration and compression. The concentrate thus obtained contained 20% by mass of fine fibrous cellulose. This concentrate was pulverized with a mixer to form a powder. A 2% by mass potassium chloride aqueous solution was added to the powdered pulverized product to make the total amount 120 g, and the mixture was stirred at 8000 rpm for 3 minutes using a disperser to obtain 120 g of a dispersion.

<Comparative Example 1>
In Example 1, 120 g of a dispersion was obtained in the same manner as in Example 1 except that no guar gum was added.

<Comparative example 2>
In Example 2, 120 g of a dispersion was obtained in the same manner as in Example 2 except that no guar gum was added.

<Comparative Example 3>
In Comparative Example 1, 120 g of a dispersion was obtained in the same manner as in Comparative Example 1, except that the sample was prepared so that the concentration of fine fibrous cellulose 1 was 0.4 mass%.

<Comparative Example 4>
In Comparative Example 1, 120 g of a dispersion was obtained in the same manner as in Comparative Example 1 except that fine fibrous cellulose 2 was used instead of fine fibrous cellulose 1.

<Comparative Example 5>
In Comparative Example 2, 120 g of a dispersion was obtained in the same manner as in Comparative Example 2, except that fine fibrous cellulose 2 was used instead of fine fibrous cellulose 1.

<Comparative Example 6>
In Comparative Example 3, 120 g of a dispersion was obtained in the same manner as in Comparative Example 3 except that fine fibrous cellulose 2 was used instead of fine fibrous cellulose 1.

<Comparative Example 7>
In Example 1, 120 g of a dispersion was obtained in the same manner as in Example 1 except that xanthan gum was used instead of guar gum.

<Comparative Example 8>
In Example 2, 120 g of a dispersion was obtained in the same manner as in Example 2 except that xanthan gum was used instead of guar gum.

(Evaluation)
The dispersions obtained in Examples and Comparative Examples were divided into two portions of 60 g, and 6 g of proppant (manufactured by SINTEX, bauxite 20/40) was added to each and stirred well to obtain dispersion A. To one of the dispersions, 0.036 g of ammonium peroxodisulfate as a decomposition agent was added and stirred well to obtain dispersion B. Each evaluation was performed as follows.

<Evaluation of proppant support>
Dispersion A was placed in a container and allowed to stand for 1 hour, and proppant support was evaluated according to the following evaluation criteria based on the ratio of the height at which the uppermost portion of proppant is located to the height of dispersion A. It can be said that the larger this value, the better the proppant supportability.
◯: The height of the top of the proppant / the height of the dispersion A is 0.8 or more. Δ: The height of the top of the proppant / the height of the dispersion A is 0.5 or more. Less than 8 ×: The height at which the top of the proppant is located / the height of the dispersion A is less than 0.5

<Evaluation of heat resistance>
Dispersion A was placed in a transparent pressure vessel (Aswan pressure bottle), sealed, placed in a 70 ° C. dryer, and heated for 6 hours. After heating, it was allowed to cool for 15 hours. Thereafter, the heat resistance was evaluated according to the following evaluation criteria based on the ratio of the height at which the uppermost part of the proppant is located to the height of the dispersion. It can be said that heat resistance is excellent, so that this value is large.
◯: The height of the top of the proppant / the height of the dispersion A is 0.8 or more. Δ: The height of the top of the proppant / the height of the dispersion A is 0.5 or more. Less than 8 ×: The height at which the top of the proppant is located / the height of the dispersion A is less than 0.5

<Evaluation of degradability>
Dispersion B was placed in a transparent pressure vessel (Aswan pressure bottle), sealed, placed in a 70 ° C. dryer, and heated for 6 hours. After heating, it was allowed to cool for 15 hours. Thereafter, the degradability was evaluated according to the following evaluation criteria based on the ratio of the height at which the uppermost portion of the proppant is located to the height of the dispersion. It can be said that the smaller the value, the better the decomposability.
○: Height of the top of the proppant / height of the dispersion A is less than 0.4 Δ: Height of the top of the proppant / the height of the dispersion A is 0.4 or more. Less than 7 x: The height of the top of the proppant / the height of the dispersion A is 0.7 or more

<Evaluation of recoverability>
The presence or absence of gel-like aggregates in the sample after the evaluation of degradability was visually confirmed, and evaluated according to the following evaluation criteria.
○: Less than 1/100 of the volume of degradable B is a gel-like aggregate, or no gel-like aggregate is confirmed Δ: 1/100 to 10 minutes of the volume of degradable B Less than 1 is a gel-like aggregate x: One-tenth or more of the volume of degradable B is a gel-like aggregate

<Measurement of viscosity>
After removing coarse solids such as proppant from dispersion A and dispersion B after evaluation of degradability, the viscosity was measured using a B-type viscometer (analog viscometer T-LVT manufactured by BLOOKFIELD). It was measured. Specifically, the viscosity of the filtrate obtained after passing the dispersion through a 355 μm mesh was measured. The viscosity of dispersion A was the viscosity before decomposition, and the viscosity of dispersion B was the viscosity after decomposition. The viscosity of the dispersion A is a viscosity related to proppant support, and the viscosity of the dispersion B is a viscosity related to decomposability.
The viscosity was measured by rotating at a rotor temperature of 3 rpm for 3 minutes at a liquid temperature of 25 ° C. In addition, in the dispersion B, those having a recoverability evaluation of x were not subjected to viscosity measurement after decomposition.

As shown in the examples, the underground treatment composition containing fine fibrous cellulose and a nonionic water-soluble polymer had various characteristics indispensable as an underground treatment fluid used as a drilling fluid. . Specifically, the underground treatment fluid obtained in the examples flows through proppant support necessary for transporting proppant, heat resistance that does not lose its characteristics even under high temperature conditions, and addition of a decomposition agent. It had four characteristics of degradability and recoverability where fluid recovery was not hindered by the re-agglomerated gel.
Examples 1-4, 6 and 8-9 were a combination of fine fibrous phosphorylated cellulose or fine fibrous maleated cellulose and guar gum, and were particularly excellent in the above four characteristics. In addition, Example 5 is a combination of fine fibrous TEMPO-oxidized cellulose and guar gum, and generally has good characteristics, and although there was a tendency to be somewhat inferior in recoverability, it was at a level causing no practical problem. In Example 10, since the content of the nonionic water-soluble polymer was large, a tendency to be slightly inferior in heat resistance was observed, but the level was not problematic in practice. In addition, as in Examples 11 and 12, even if the composition for treating the underground layer is concentrated and then mixed with the fluid to obtain the fluid for treating the underground layer, the same characteristics as in the other examples are obtained. It was done.
Examples 7 and 12 were obtained by adding xanthan gum and showed good results despite being dispersed in salt water, indicating that the present invention is effective even in salt water.
Comparative Examples 1 to 6 do not contain a water-soluble polymer. Propant support is not sufficient if the fine fibrous cellulose is at a low concentration, and reaggregation after decomposition if the fine fibrous cellulose is at a high concentration. However, the recoverability was poor.
Comparative Examples 7 and 8 were obtained by adding xanthan gum, which was an ionic water-soluble polymer, but were poor in proppant support, unlike guar gum, which was a nonionic water-soluble polymer.

Claims (19)

And following fine fibrous cellulose 1000nm fiber width is a non-ionic water-soluble polymer, only including,
The composition for underground layer treatment , wherein the fine fibrous cellulose is phosphorylated cellulose or maleated cellulose .   The composition for underground layer treatment according to claim 1, wherein the content of the nonionic water-soluble polymer is 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the fine fibrous cellulose.   The composition for underground layer treatment according to claim 1 or 2, wherein the nonionic water-soluble polymer is guar gum.   The composition for underground layer treatment according to any one of claims 1 to 3, wherein the fine fibrous cellulose has an anionic substituent. The composition for underground layer treatment according to any one of claims 1 to 4 , wherein the fine fibrous cellulose has an anionic substituent of 0.1 mmol / g to 3.5 mmol / g per gram of fine fibrous cellulose. . Furthermore, the composition for underground layer treatment of any one of Claims 1-5 containing an ionic water-soluble polymer. Content of the said fine fibrous cellulose is 3 mass% or more with respect to the total mass of the said composition for underground layer treatment, The composition for underground layer treatment of any one of Claims 1-6 . And following fine fibrous cellulose 1000nm fiber width is a non-ionic water-soluble polymer, and a fluid, only including,
The fluid for underground layer treatment , wherein the fine fibrous cellulose is phosphorylated cellulose or maleated cellulose . Furthermore, the underground process fluid of Claim 8 containing a decomposition agent. The underground layer treatment fluid according to claim 8 or 9 , wherein the decomposing agent is an oxidizing agent. Further the average particle diameter of claims 8-10 subterranean treatment fluid according to any one of including the following granules 10mm or 0.1 mm. The underground layer treatment according to any one of claims 8 to 11 , which has a viscosity of 3000 mPa · s or more measured at a liquid temperature of 25 ° C using a B-type viscometer at a rotation speed of 3 rpm and a measurement time of 3 minutes. fluid. The viscosity of the supernatant after adding ammonium peroxodisulfate to the above-mentioned underground layer treatment fluid to 0.06% by mass and allowing to stand at 70 ° C. for 6 hours, at a liquid temperature of 25 ° C. The fluid for underground layer treatment according to any one of claims 8 to 12 , which has a viscosity of 800 mPa · s or less measured at 3 rpm and a measurement time of 3 minutes. A step of mixing a fine fibrous cellulose having a fiber width of 1000 nm or less and a nonionic water-soluble polymer to obtain a composition for treating an underground layer;
A method of producing a fluid for treating an underground layer comprising the step of mixing the composition for treating an underground layer and a fluid ,
The method for producing a fluid for treating an underground layer, wherein the fine fibrous cellulose is phosphorylated cellulose or maleated cellulose. The method for producing a fluid for underground formation treatment according to claim 14 , further comprising a step of adding a decomposition agent after the step of obtaining the composition for underground formation treatment. The method for producing a fluid for treating an underground layer according to claim 14 or 15 , further comprising a step of adding a granular material having an average particle diameter of 0.1 mm or more and 10 mm or less after the step of obtaining the composition for treating the underground layer. Processing method of subterranean formations comprising the step of flowing the subterranean treatment fluid according to subterranean to any one of claims 8-13. The method further includes a step of recovering a post-treatment fluid containing at least the fine fibrous cellulose, the nonionic water-soluble polymer, and the fluid after the step of causing the underground layer treatment fluid to flow into the underground layer. Item 18. A method for treating an underground layer according to Item 17 . The method includes the step of settling the particulate matter having an average particle diameter of 0.1 mm or more and 10 mm or less between the step of flowing the underground processing fluid into the underground layer and the step of recovering the processed fluid. The processing method of the underground layer of 17 or 18 .