JP2014218533A - Resin-coated sand dispersant and proppant composition for gas well or oil well - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated sand dispersant for gas wells or oil wells, capable of improving dispersibility in dispersion of proppant into a proppant-transporting gel and of reducing the amount of the proppant used.SOLUTION: A resin coated sand dispersant for gas wells or oil wells is characterized by comprising divalent fatty acid metal salt particles obtained by reacting a fatty acid alkali compound salt obtained by reacting an univalent alkali compound with a fatty acid having a carbon number of 8 to 24, with a divalent metal salt in an aqueous solution.

Description

  The present invention is a dispersing agent for dispersing resin-coated sand, which is a hydraulic crushing proppant used for collecting shale gas, in a transport gel, and the dispersion when proppant is dispersed in the proppant transport gel The present invention relates to a resin-coated sand dispersant for gas or oil wells that can improve the properties and reduce the amount of proppant used. The present invention also relates to a proppant composition containing the dispersant and a resin coated sand for a gas well or oil well.

  In the hydraulic fracturing method used in gas wells or oil wells, a fine substance called proppant is gradually injected into the well while being mixed with a highly viscous gel, and cracks are generated in the reservoir rock near the well. Propant in the gel plays a role of supporting the cracks generated in the vicinity of the wells in an open state, securing gas and oil passages, and increasing the production of wells.

Conventionally, silica sand and silica have been used as proppants, but in recent years, resin coated sand in which thermosetting resin is coated on silica sand or artificial ceramic has been used (see Patent Document 1). . Specifically, a thermosetting resin such as a phenol resin is heated to be liquefied, and silica coated sand or artificial ceramic is coated to prepare a resin coated sand. The resin coating sand obtained in this way remains at the crack site of the shale layer, for example, at the time of shale gas collection, and the resin coating sand particles are firmly bonded to each other by hardening with gas heat so that the crack is closed. Can withstand the pressure of
However, the resin-coated sand has a high surface stickiness, and a blocking phenomenon in which particles are bonded to each other through the resin before use is likely to occur. Therefore, even when the resin-coated sand is dispersed in the highly viscous gel, there is a problem that the dispersibility is low because it is easily aggregated, and as a result, a large amount of proppant is required.

Special table 2007-532721 gazette

  The present invention has been made in view of the above problems, and improves the dispersibility when proppant is dispersed in a proppant transport gel and can reduce the amount of proppant to be used. It is an object of the present invention to provide a proppant composition containing a dispersant, the dispersant, and a resin coated sand for a gas well or oil well.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a divalent fatty acid metal salt particle having 8 to 24 carbon atoms obtained by metathesis, preferably a specific particle size summary value and a specific aggregation degree. The divalent fatty acid metal salt particles having a specific loose bulk density, a specific average circularity C, and powder properties in which a value obtained by dividing the particle size summary value by the average circularity falls within a specific range. The present inventors have found that the dispersibility when resin-coated sand is dispersed in a highly viscous gel can be improved and the amount of proppant to be used can be reduced, thereby completing the present invention.

  That is, the present invention was obtained by reacting a fatty acid alkali compound salt obtained by reacting a monovalent alkali compound with a fatty acid having 8 to 24 carbon atoms and a divalent metal salt in an aqueous solution. A resin-coated sand dispersant for gas wells or oil wells (hereinafter, also simply referred to as a dispersant), characterized by comprising divalent fatty acid metal salt particles.

The dispersant of the present invention has a particle size summary value A represented by the following formula (1) of 2.0 or less, and is measured with a powder tester in the fatty acid metal salt particles left in an environment of 80 ° C. for 10 minutes. It is preferable that the degree of aggregation B (%) represented by the following formula (2) satisfies the relationship of B ≦ 20.
(1) Formula particle size summary value A = (D90−D10) / D50 (where 1.0 ≦ D50 ≦ 40.0)
D10: 10% integrated diameter (μm) of fatty acid metal salt particles based on volume
D50: Median diameter (μm) of fatty acid metal salt particles based on volume
D90: 90% integrated diameter (μm) of fatty acid metal salt particles based on volume

(2) Formula Cohesion B = [(mass of fatty acid metal salt particles remaining on sieve with 350 μm sieve) / 2] × 100 × (1/1) + [(fatty acid metal salt remaining on sieve with 250 μm sieve mesh) Particle Mass) / 2] × 100 × (3/5) + [(Mass of Fatty Acid Metal Salt Particles Remaining on Sieve 150 μm) / 2] × 100 × (1/5)]

  Furthermore, in the dispersant of the present invention, when the divalent fatty acid metal salt particles are measured by a flow type particle image analyzer, the average circularity C of a particle group having a particle size of 10% to 90% is 0.810. It is preferably ˜1.000.

  In the dispersant of the present invention, the divalent metal constituting the divalent fatty acid metal salt particles is preferably calcium.

  Further, the present invention is a proppant composition containing the dispersant of the present invention and a resin coated sand for gas wells or oil wells (hereinafter also simply referred to as resin coated sand).

  According to the present invention, since the anti-blocking property of the resin-coated sand can be enhanced, the dispersibility when dispersed in a highly viscous gel can be improved, and the amount of proppant used can be reduced.

  Hereinafter, embodiments of the present invention will be described. The resin-coated sand dispersant for a gas well or oil well, the resin-coated sand, and the high-viscosity gel as a dispersion medium according to the present invention will be described in order.

(1) Resin coated sand dispersant for gas well or oil well The dispersant used in the present invention is a fatty acid alkali compound salt obtained by reacting a monovalent alkali compound with a fatty acid having 8 to 24 carbon atoms, It consists of divalent fatty acid metal salt particles prepared by a metathesis method in which a divalent metal salt is reacted in an aqueous solution.

  The fatty acid used as the raw material for the fatty acid alkali compound salt is not particularly limited as long as it is a fatty acid having 8 to 24 carbon atoms. That is, any of a naturally occurring fatty acid and a synthetic fatty acid may be used, and either a saturated fatty acid or an unsaturated fatty acid may be used. Preferably, it is a linear saturated fatty acid having 12 to 22 carbon atoms. When the number of carbon atoms is less than 8, it is difficult to obtain an effect as a dispersant for the obtained fatty acid metal salt particles. On the other hand, fatty acids having more than 24 carbon atoms are difficult to obtain industrially, and the solubility of the resulting fatty acid alkali compound salt in water is significantly reduced, resulting in low productivity.

  Examples of the fatty acid include caprylic acid, capric acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitooleic acid, stearic acid, oleic acid, linoleic acid, arachidic acid, behenic acid, erucic acid and Examples thereof include hydroxystearic acid, among which stearic acid is preferred. When using a mixed fatty acid, a mixed fatty acid having a stearic acid content of preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more is used.

  Examples of the monovalent alkali compound used as the raw material for the fatty acid alkali compound salt include hydroxides of alkali metals (sodium, potassium, etc.) and amines such as ammonia, monoethanolamine, diethanolamine, and triethanolamine. From the viewpoint of high solubility in water when a fatty acid alkali compound salt is used, an alkali metal hydroxide such as sodium or potassium is preferred.

  The fatty acid alkali compound salt used in the present invention generally has a monovalent alkali compound and a fatty acid at a temperature that is not lower than the melting point of the fatty acid and does not decompose the fatty acid, preferably 100 ° C. or lower, more preferably 50 to It is obtained by reacting at 100 ° C., more preferably 60 to 95 ° C., particularly preferably 70 to 95 ° C.

  The divalent fatty acid metal salt particles used in the present invention are fatty acid metal salt particles obtained by reacting the fatty acid alkali compound salt obtained above with a divalent metal salt in an aqueous solution. The divalent metal salt is specifically a salt of a divalent inorganic metal and an inorganic acid or an organic acid. Examples of divalent inorganic metals include alkaline earth metals such as magnesium, calcium and barium, transition metals such as titanium, zinc, iron, manganese, cadmium, mercury, zirconium, lead, copper, cobalt, aluminum and nickel. It is done. Among these, calcium and magnesium are preferable, and calcium is particularly preferable because it is less burdensome on the environment and easily available industrially.

  Examples of the divalent metal salt include calcium chloride, calcium acetate, magnesium chloride, magnesium sulfate, zinc chloride, zinc sulfate, and aluminum sulfate. In particular, chlorides such as calcium and magnesium, sulfates, and nitrates are preferable because they have high solubility in water and efficiently react with fatty acid alkali compound salts.

Specifically, the above reaction is performed by separately preparing a divalent metal salt-containing aqueous solution and a fatty acid alkali compound salt-containing aqueous solution, and then mixing them. For example, the divalent metal salt-containing aqueous solution is added to the fatty acid alkali compound salt-containing aqueous solution, or both are added to another reaction tank.
When mixing the fatty acid alkali compound salt-containing aqueous solution and the divalent metal salt-containing aqueous solution, for example, when the divalent metal salt-containing aqueous solution is added at once to the fatty acid alkali compound salt-containing aqueous solution, the resulting fatty acid metal salt particles There is a possibility that the shape of the material becomes non-uniform and the particle size distribution becomes wide. Therefore, in the present invention, it is preferable that the divalent metal salt-containing aqueous solution is gradually dropped at an appropriate rate with respect to the fatty acid alkali compound salt-containing aqueous solution.

  The concentration of the fatty acid alkali compound salt during the production of the fatty acid metal salt is usually 1% by mass to the productivity of the fatty acid metal salt and the handling property of the fatty acid alkali compound salt-containing aqueous solution or the resulting fatty acid metal salt slurry. 20% by mass, preferably 5% by mass to 15% by mass. When the concentration of the fatty acid alkali compound salt is less than 1% by mass, the productivity of the fatty acid metal salt may decrease, which is not practically preferable. When the amount exceeds 20% by mass, the viscosity of the fatty acid alkali compound salt-containing aqueous solution or the resulting fatty acid metal salt slurry increases, so that it may be difficult to perform a uniform reaction. The concentration of the divalent metal salt in the divalent metal salt-containing liquid is determined from the viewpoint of the productivity of the fatty acid metal salt, and the handling property of the fatty acid alkali compound salt-containing aqueous solution or the obtained fatty acid metal salt slurry. Usually, it is 10 mass%-50 mass%, Preferably it is 10 mass%-40 mass%.

  The reaction between the fatty acid alkali compound salt and the divalent metal salt is performed under temperature conditions that are usually performed by those skilled in the art in consideration of the solubility of the fatty acid alkali compound salt. Preferably it is 50-100 degreeC, More preferably, it is 60-95 degreeC. When reaction temperature is less than 50 degreeC, there exists a possibility that the reaction rate of a fatty-acid alkali compound salt and a bivalent metal salt may fall.

  Polyalkylene glycol ethers, especially oxypropylene blocks, are the oxyethylene blocks for the purpose of stabilizing the fatty acid metal salt slurry during the reaction between the fatty acid alkali compound salt and the divalent metal salt and improving the productivity of the fatty acid metal salt. It is preferable that a triblock ether having a structure sandwiched between (EO-PO-EO) is present in the fatty acid metal salt slurry. The content of the polyalkylene glycol ether in the fatty acid metal salt slurry is usually 0.01 to 5 parts by mass, preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the fatty acid alkali compound salt. is there. The polyalkylene glycol ether may be present in the reaction system before reacting the monovalent alkali compound with the fatty acid, or the reaction system before the reaction between the fatty acid alkali compound salt and the divalent metal salt. May be present.

  By the above method, a fatty acid metal salt slurry is obtained. This fatty acid metal salt slurry is used as it is or after separating the solvent by a centrifugal dehydrator, filter press, vacuum rotary filter, etc., and if necessary, washing and removing by-product inorganic salts, Drying is performed by an air dryer, an aeration dryer, a spray dryer, a fluidized bed dryer or the like. The drying method may be continuous, batch, normal pressure or vacuum. Furthermore, the dried fatty acid metal salt is pulverized as necessary. The pulverization method is not particularly limited, and for example, a pin mill, a jet mill, an atomizer or the like can be used. The pulverized fatty acid metal salt particles are classified. That is, classification is performed using a multistage sieving apparatus or the like that applies vibrations and performs sieving to adjust the particle size distribution. In this way, fatty acid metal salt particles as the dispersant of the present invention can be obtained.

The fatty acid metal salt particles used in the present invention are divalent fatty acid metal salt particles having 8 to 24 carbon atoms obtained by metathesis, and preferably have a narrow particle size distribution so that the resin-coated sand is obtained. It becomes possible to coat uniformly, and accordingly, it becomes easy to express high uniform dispersibility in the high-viscosity gel as a dispersion medium.
Specifically, it is preferable that the particle size summary value A represented by the following formula (1) of the fatty acid metal salt particles is 2.0 or less. In the present invention, the particle size summary value A is calculated from the particle size measured by the microtrack laser diffraction method. When the particle size summary value A exceeds 2.0, the dispersion of the fatty acid metal salt coated on the resin-coated sand becomes uneven due to the dispersion of the particle diameter, so that the resin-coated sand not only easily causes blocking but also a highly viscous gel. There is a possibility that a large amount of propand may be required due to a decrease in stability inside.

  More preferably, the particle size summary value A satisfies the relationship of 1.0 ≦ A ≦ 1.8. When the relationship of 1.0 ≦ A ≦ 1.8 is satisfied, the effects of the present invention can be obtained more stably. When the particle size summary value A is less than 1.0, it may be difficult to produce industrially, for example, the yield may be significantly reduced.

  The particle size summary value A is adjusted by adjusting the concentration of the fatty acid alkali compound salt, the temperature during the reaction between the fatty acid alkali compound salt and the divalent metal salt, and dropping the divalent metal salt-containing aqueous solution into the fatty acid alkali compound salt-containing aqueous solution. It can carry out by adjusting the dripping speed | rate at the time of carrying out suitably, respectively. In addition, those having a wide particle size distribution, that is, a particle size summary value A having a large value can be obtained by classification using a sieve of 100 mesh, 200 mesh, 330 mesh or the like in post-processing.

  The microtrack laser diffraction method used here is a method for obtaining a particle size distribution using scattered light obtained by irradiating particles with laser light. In the present invention, the measurement is performed by a wet method in which an organic solvent in which the fatty acid metal salt particles are not dissolved, for example, an organic solvent such as ethanol or isopropyl alcohol is circulated, and the sample is directly added. Moreover, the measurement object in this invention is the range of a particle diameter of 0.1 micrometer-200 micrometers, and let the value represented by the following (1) formula be the particle size summary value A. In the present invention, measurement can be performed using, for example, Microtrack MT-3000 manufactured by Nikkiso Co., Ltd.

(1) Formula particle size summary value A = (D90−D10) / D50 (where 1.0 ≦ D50 ≦ 40.0)
D10: 10% integrated diameter (μm) of fatty acid metal salt particles based on volume
D50: Median diameter (μm) of fatty acid metal salt particles based on volume
D90: 90% integrated diameter (μm) of fatty acid metal salt particles based on volume

  According to the study of the present inventors, the aggregation degree B (%) represented by the following formula (2) measured by a powder tester when the fatty acid metal salt particles are left in an environment of 80 ° C. for 10 minutes is B ≦ By satisfying the relationship of 20, the fatty acid metal salt particles can be easily released even under mild mixing conditions of the resin-coated sand, and can be quickly and uniformly dispersed in the resin-coated sand. High uniform dispersibility is easily expressed in a highly viscous gel as a medium.

  The adjustment of the degree of aggregation B is performed by carrying out the reaction between the fatty acid alkali compound salt and the divalent metal salt under mild conditions and preventing aggregation of the fatty acid metal salt particles in the slurry obtained by the reaction. Can do. That is, for example, the reaction can be performed at a mild temperature that does not decrease the reaction rate during the reaction between the fatty acid alkali compound salt and the divalent metal salt, or by shortening the aging time. By appropriately adjusting these factors during the reaction, the degree of aggregation B can be adjusted within the range specified in the present invention.

  The degree of aggregation B (%) is more preferably 2 ≦ B ≦ 18, further preferably 2 ≦ B ≦ 15, and particularly preferably 2 ≦ B ≦ 13. When 2 ≦ B ≦ 13 is satisfied, the operational effects of the present invention can be obtained more stably.

(2) Formula Cohesion B = [(mass of fatty acid metal salt particles remaining on sieve with 350 μm sieve) / 2] × 100 × (1/1) + [(fatty acid metal salt remaining on sieve with 250 μm sieve mesh) Particle Mass) / 2] × 100 × (3/5) + [(Mass of Fatty Acid Metal Salt Particles Remaining on Sieve 150 μm) / 2] × 100 × (1/5)]

The aggregation degree B of the fatty acid metal salt particles by the powder tester used here is a value obtained by the following measuring method. That is, for example, the following steps (a) to (f) are performed using a powder tester (manufactured by Hosokawa Micron Corporation, PT-N type).
(A) The fatty acid metal salt particles to be measured are left for 10 minutes in a thermostat set to 80 ° C.
(B) Sieves of 350 μm, 250 μm, and 150 μm are sequentially set from the upper layer on the vibrating table of the powder tester.
(C) Immediately place 2.0 g of fatty acid metal salt particles after step (a) gently on a sieve having a sieve size of 350 μm.
(D) Vibrate the sieve with an amplitude of 1 mm for 105 seconds.
(E) The mass of the fatty acid metal salt particles remaining on each sieve is measured.
(F) A value obtained by multiplying each mass obtained in the step (e) by a weight of 1/1, 3/5, and 1/5 in order, and adding these to calculate the percentage by the above equation (2). Is a degree of aggregation B (%).
The above steps (a) to (f) are repeated five times, and the average value is taken as the measured value.

  Furthermore, in the fatty acid metal salt particles used in the present invention, the loose bulk density (Da) (g / cc) represented by the following formula (3) is preferably 0.110 ≦ Da ≦ 0.180, More preferably, 135 ≦ Da ≦ 0.160. When 0.110 ≦ Da ≦ 0.180, high slipperiness is obtained when the resin-coated sand is added to the high-viscosity gel as a dispersion medium, and uniform dispersibility is more easily exhibited.

  The loose bulk density (Da) is a value obtained by the following measuring method. First, for example, a powder tester (made by Hosokawa Micron Corporation, PT-N type) is used, and a sieve with a mesh size of 710 μm is set on a vibration table, and a sample of 250 cc is placed therein, vibrated for 30 seconds, and placed under the sieve. Collect the dropped sample in the measuring cup. Using the attached blade, scrape excess fatty acid metal salt particles on the cup, and then measure the mass of the cup containing the sample. In the present invention, this operation / measurement is repeated five times, and the average value is taken as the measurement value of the bulk density (Da). In the PT-N type, the measured value is automatically displayed.

(3) Formula Loose bulk density (Da) (g / cc) = mass of cup containing sample (g) / volume of cup (cc)

  The fatty acid metal salt particles used in the present invention have an average circularity C of a particle group of 10% particle diameter to 90% particle diameter of 0.810 to 1.000 as measured by a flow particle image analyzer. Is preferable, 0.820 to 0.950 is more preferable, and 0.830 to 0.920 is particularly preferable.

  The average circularity C is adjusted by performing the reaction between the fatty acid alkali compound salt and the divalent metal salt under mild conditions, and the particle shape of the fatty acid metal salt particles in the slurry obtained by the reaction becomes nonuniform. Can be done by preventing. That is, for example, the reaction is performed at a mild temperature that does not reduce the reaction rate during the reaction between the fatty acid alkali compound salt and the divalent metal salt, or the divalent metal salt-containing aqueous solution is changed to the fatty acid alkali compound salt-containing aqueous solution. The dropping can be performed by slowing the dropping speed or adding the above-mentioned polyalkylene glycol ether to stabilize the slurry. By appropriately adjusting these factors during the reaction, the average circularity C can be adjusted within the range specified in the present invention.

  The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the fatty acid metal salt particles, and can be defined as follows. First, for example, using a flow type particle image analyzer “FPIA-3000” manufactured by Sysmex Corporation, particles within a circle equivalent diameter of 0.5 μm to 200 μm are measured, and the circularity (ai) of each particle measured there. Are obtained by the following equation (4).

Equation (4) Circularity (ai) = (perimeter of a circle having the same area as the projected image of the particle) / (perimeter of the projected particle image)

  Furthermore, for particles in the range of the equivalent circle diameter of 0.5 μm to 200 μm, the value obtained by dividing the total sum of the circularity of all measured particles by the total number of particles (m), as shown by the following equation (5): The average circularity (a) is defined.

  The average circularity in the present invention is an index indicating the degree of unevenness of the particle shape of the fatty acid metal salt. As the surface shape of the fatty acid metal salt particle becomes closer to a circle, it approaches 1.000, and the surface shape of the particle becomes complicated. The average circularity becomes a small value. “FPIA-3000”, which is a measuring apparatus that can be used in the present invention, calculates the circularity of each particle, and classifies the circularity of particles from 0.4 to 1.0 into 61 by the obtained circularity. A calculation method is used in which the average circularity is calculated using the center and frequency of the division points.

  In the present invention, the average circularity C (hereinafter, also simply referred to as “average circularity C”) of a particle group having a particle size of 10% to 90% is a particle size among all particles measured by the measuring device. This is a value obtained by dividing the total circularity of particles in the range of 10% particle diameter to 90% particle diameter from the small particle diameter side of the distribution by the number of particles.

  The average circularity C of a particle group having a particle size of 10% to 90% is measured, for example, as follows. 30 ml of ion-exchanged water from which impure solids and the like have been removed in advance is prepared in a container, and a surfactant, preferably polyoxyethylene-lauryl ether (manufactured by NOF Corporation, trade name: Nonion K-) as a dispersant therein. After adding 204), 20 mg of a measurement sample is further added and dispersed uniformly. As a dispersing means, for example, an ultrasonic dispersing machine UH-50 type (manufactured by SMT Co., 20 kHz, 50 W) equipped with a titanium alloy chip having a diameter of 5 mm as a vibrator is subjected to a dispersion treatment for 5 minutes. The concentration is set to 3,000 / 20,000 to 20,000 / ml to obtain a dispersion for measurement. At that time, the measurement is performed while cooling appropriately so that the temperature of the dispersion liquid for measurement does not become 40 ° C. or higher. Thereafter, measurement is performed using a flow type particle image analyzer “FPIA-3000”, and the average circularity C is obtained by processing the obtained data.

When the present inventors use the obtained fatty acid metal salt particles as a dispersant, among the obtained powder physical properties, the average circularity C of a particle group having a particle size of 10% to 90%, and (1) It has been found that the numerical relationship with the particle size summary value A of the formula has a great influence on the coating property on the resin-coated sand. That is, from the viewpoint of improving the coating property on the resin-coated sand, 0 <(particle size summary value A / average circularity C) ≦ 2.5, and 0 <(particle size summary value A / average circularity C) ≦ 2. .3 is preferable, and 0 <(particle size summary value A / average circularity C) ≦ 2.1 is more preferable.
As the value of (particle size summary value A / average circularity C) is smaller, the particle size distribution of the fatty acid metal salt becomes narrower and uniform, and the shape of each particle becomes closer to a circle. By uniformly dispersing and further improving the coating property to the resin-coated sand particles, it becomes easy to express high uniform dispersibility in the highly viscous gel.

  The dispersant of the present invention may be used by mixing with a nonionic surfactant. As the nonionic surfactant, an ether type nonionic surfactant is desirable, and polyoxyethylene alkyl ether is more desirable. This is because the fatty acid metal salt particles and the nonionic surfactant are used in combination in the stability of the formation of fatty acid metal salt particles in the slurry and the dispersion stability of the resin-coated sand by the obtained fatty acid metal salt particles. It is because it is excellent.

  The dispersant of the present invention is a divalent fatty acid metal salt particle having 8 to 24 carbon atoms obtained by metathesis, and preferably has a specific particle size summary value A, a specific aggregation degree B, a specific value as described above. And a specific average circularity C, and a powder physical property in which a value obtained by dividing the particle size summary value A by the average circularity C falls within a specific range. Such fatty acid metal salt particles can be quickly and uniformly dispersed even under the addition conditions during the production of the resin-coated sand, can be effectively coated on the resin-coated sand particles, and are high in a highly viscous gel. This is preferable because uniform dispersibility is easily exhibited.

(2) Resin-coated sand for gas well or oil well The resin-coated sand is composed of a granular sand material and a thermosetting resin that coats the granular sand material.

  The granular sand materials that make up the resin-coated sand include quartz sand, chromite sand, zircon sand, olivine sand, mullite sand, synthetic mullite sand, magnesia, special sand, ceramic and their recovered sand, recycled. Etc. In the present invention, fresh sand, recovered sand, reclaimed sand, or a mixed sand thereof can be used. Further, the particle size distribution and particle shape of the granular material can be selected without particular limitation as long as it is suitable for the hydraulic fracturing process.

  Bentonite, water glass, starch, etc. can be used as the thermosetting resin constituting the resin-coated sand, but phenol resin, furan resin, urethane resin, amine polyol such as resol type, novolac type, benzylic ether type, etc. It is preferable to use one or a combination of two or more thermosetting resins such as resins and polyether polyol resins. In addition, if necessary, hexamethylenetetramine, isocyanate, organic esters, phosphate esters, etc. are blended as curing agents, and tertiary amines, sulfur dioxide, pyridine derivatives, organic sulfonic acids, etc. are blended as curing accelerators. Thus, it can be used by making it thermosetting self-curing.

  The compounding quantity of a thermosetting resin is 0.1-10 mass% with respect to a granular sand material. Moreover, the compounding quantity in the case of using a hardening | curing agent is 10-30 mass% with respect to a thermosetting resin.

(3) Propant composition The proppant composition of this invention contains the dispersing agent of this invention, and the said resin well-coated sand for gas wells or oil wells.
In the proppant composition of the present invention, for example, a granular sand material heated to a predetermined temperature is charged into a mixer, and the above-described thermosetting resin is melt-coated on the granular sand material. It can be manufactured by kneading. More specifically, the granular sand material is heated to, for example, 130 to 160 ° C., the heated granular sand material and the thermosetting resin are kneaded, and then an aqueous solution containing, for example, hexamethylenetetramine is added as a curing agent. Then, knead until the lump of granular sand material collapses. Furthermore, it cools to 70-90 degreeC, the dispersing agent of this invention is thrown in, and it disperse | distributes on mild conditions for about 20-60 seconds, and the proppant composition of this invention is obtained.

  The compounding quantity of the dispersing agent of this invention is 0.01-1 mass% with respect to resin coated sand, Preferably it is 0.01-0.5 mass%.

(4) High-viscosity gel In the hydraulic fracturing method, a high-viscosity gel is used for transporting resin-coated sand, which is a hydraulic fracturing proppant, into the well. The high-viscosity gel mainly contains water and a gelling agent that swells by forming a three-dimensional cross-linked structure using hydrogen bonds of water molecules.
As the gelling agent, the gelation rate is relatively fast and the gel viscosity is preferably high. For example, agar, carrageenan, xanthan gum, gellan gum, guar gum, polyvinyl alcohol, polyacrylate thickener, carboxymethylcellulose And water-soluble celluloses such as hydroxypropylmethylcellulose, and chitansan gum and guar gum are preferably used. A highly viscous gel can be prepared according to a well-known method.

  The proppant composition of this invention can add 1-30 mass% with respect to a highly viscous gel, Preferably 5-25 mass% can be added. Usually, the proppant composition is stirred and dispersed in a highly viscous gel using a mixer or the like.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

(Example 1: Preparation of resin-coated sand dispersant)
3L separable flask containing mixed fatty acids (2.1% by weight myristic acid, 30.3% by weight palmitic acid, 66.5% by weight stearic acid, 0.8% by weight arachidic acid, and 0.3% by weight behenic acid) ) 250 g and 2500 g of water were charged, and the temperature was raised to 90 ° C. Subsequently, 77.2 g of 48 mass% sodium hydroxide aqueous solution was added, and it stirred at the same temperature (90 degreeC) for 1 hour, and obtained fatty-acid alkali compound salt aqueous solution. Then, 151.2 g of 35 mass% calcium chloride aqueous solution was dripped at the fatty-acid alkali compound salt aqueous solution over 1 hour, hold | maintaining at 90 degreeC. After completion of dropping, the mixture was further stirred at 90 ° C. for 1 hour. 1500 g of water was added to the obtained mixed fatty acid calcium salt aqueous solution slurry and cooled to 65 ° C. or lower. Thereafter, the mixture was filtered with a suction filter, washed twice with 1000 g of water, and the resulting cake was dried, pulverized and classified with a micron dryer to obtain fatty acid calcium salt particles.

(Example 2)
3L separable flask containing mixed fatty acids (1.6% by weight myristic acid, 24.0% by weight palmitic acid, 73.4% by weight stearic acid, 0.7% by weight arachidic acid, and 0.3% by weight behenic acid) ) 250 g, 0.75 g of polyethylene glycol / polypropylene glycol / block ether (manufactured by NOF Corporation, trade name: Pronon # 104) and 2500 g of water were charged, and the temperature was raised to 90.degree. Subsequently, 76.5 g of 48 mass% sodium hydroxide aqueous solution was added, and it stirred at the same temperature (90 degreeC) for 1 hour, and obtained fatty-acid alkali compound salt aqueous solution. Then, 150.1 g of 35 mass% calcium chloride aqueous solution was dripped at the fatty-acid alkali compound salt aqueous solution over 1 hour, hold | maintaining at 90 degreeC. After completion of dropping, the mixture was further stirred at 90 ° C. for 1 hour. 1500 g of water was added to the obtained mixed fatty acid calcium salt aqueous solution slurry and cooled to 65 ° C. or lower. Thereafter, the mixture was filtered with a suction filter, washed twice with 1000 g of water, and the resulting cake was dried, pulverized and classified with a micron dryer to obtain fatty acid calcium salt particles.

(Comparative Example 1)
Fatty acid mixed in 10 L pressure kneader (containing myristic acid 2.4% by mass, palmitic acid 31.1% by mass, stearic acid 65.4%, arachidic acid 0.8% by mass, and behenic acid 0.3% by mass) After adding 250 g and heating to 100 ° C., 68.0 g of quicklime was added, the temperature was gradually raised to 140 ° C. while stirring, and the mixture was reacted for 1 hour. The obtained mixed fatty acid calcium salt was dried in a thermostatic bath at 80 ° C. for 3 days, pulverized with a bantam mill, and passed through a 60 mesh sieve to obtain a sample.

  For the fatty acid metal salt particles of Examples 1 and 2 and Comparative Example 1, the particle size summary value A [volume-based 10% cumulative diameter D10 (μm), volume-based median diameter D50 (μm), volume-based 90% cumulative diameter The value calculated from D90 (μm)], the loose bulk density (Da) (g / cc), and the degree of aggregation B (%) were measured by the methods described above using the following apparatuses. The results are shown in Table 1.

(1) Particle size The particle size was measured with a particle size distribution measuring device (device name “Microtrack MT-3000” manufactured by Nikkiso Co., Ltd.). Principle: Laser diffraction / scattering method (2) Loose bulk density Measured with a powder property evaluation apparatus (device name “Powder Tester PT-N type” manufactured by Hosokawa Micron Corporation).
(3) Aggregation degree It measured with the powder characteristic evaluation apparatus (Equipment name "powder tester PT-N type" Hosokawa Micron Corporation make).
(4) Average circularity Measurement was carried out in an aqueous dispersion system using a flow particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation).

[Production of proppant composition]
5 kg of silica sand having a particle size of 50 mesh pass as a granular sand material was heated to 150 ° C., and kneaded for 45 seconds with a speed mixer with 100 g of phenol resin (2.0 mass% / granular sand material) as a thermosetting resin. Thereafter, 115 g of a hexamethylenetetramine aqueous solution in which 15 g (15.0% by mass / thermosetting resin) of hexamethylenetetramine (reagent) and 100 g of water are mixed and dissolved in advance is added and kneaded until the lump of sand is broken. did. At about 80 ° C., 2.5 g (0.10 mass% / granular sand material) of the fatty acid metal salt particles obtained in the above examples and comparative examples was added, mixed and kneaded for 30 seconds, then discharged from the mixer and proppant composition. I got a thing.

[Blocking evaluation of proppant composition]
The obtained proppant composition was put in 200 g of each of three-layer kraft paper bags (20 cm × 10 cm) each having a vinyl resin layer inside, and the proppant composition in the bag was flattened to a thickness of about 3 cm. A plate (length × width × thickness = 200 mm × 400 mm × 10 mm; weight 200 g) was placed on the bag. Then, a load of 16 kg was applied, and it was held for 7 days in a constant temperature / humidity chamber maintained at a temperature of 40 ± 2 ° C. and a humidity of 65 ± 5%.
Thereafter, the proppant composition was taken out of the bag and the occurrence of blocking (lumps) was observed with the naked eye, and the entire amount was put into a sieve having a sieve opening of 425 μm (40 mesh), and the sieve was lightly tapped 50 times by hand. The mass of the proppant composition remaining on the sieve was measured as a blocking generation amount. The ratio with respect to 100 g of the proppant composition filled in the bag was determined as a blocking occurrence rate (%), and the formation status of the lump was compared.

[Production and dispersion stability of gel for proppant transport]
Prepare 500 mL of a 0.1% by weight aqueous solution of guar gum, add 45 g (9% by weight) of the above proppant composition to the 0.1% by weight aqueous solution of guar gum, and stir for 4 minutes at 300 rpm for 3 minutes. A transport gel was produced.
The dispersion stability of the resulting proppant transport gel was evaluated. Visually check for non-uniformity such as agglomeration / sedimentation.If no agglomeration / sedimentation was observed after agitation, “○”. If agglomeration occurred but sedimentation did not occur, no solid-liquid separation was observed. “△”, when agglomeration / sedimentation occurred and solid-liquid separation was observed, “×” was evaluated. The evaluation results are shown in Table 2.

  From the results in Table 2, No. 1 in Table 1 was obtained. 1 and no. The resin-coated sand dispersant using the fatty acid calcium salt particles of No. Compared to 3, the particle size summary value A is small, the particle size is uniform, the cohesion B is low, so the dispersibility in the resin-coated sand is high, and the average circularity is also high, so it covers the resin-coated sand Since the property is high, the incidence of blocking can be suppressed. Further, when the proppant composition was dispersed in a gel using guar gum as a gelling agent, no aggregation or sedimentation of the resin-coated sand particles was observed, resulting in high dispersion stability.

On the other hand, no. The resin-coated sand dispersant using the fatty acid calcium salt particles of No. 3 is low in dispersibility due to the large particle size summary value A and the non-uniform particle diameter, and low in average circularity. Since the covering property was low, it was easy to cause blocking. Moreover, partial aggregation was observed in the gel using guar gum.
No. No resin coated sand dispersant in Table 2 is used. In No. 4, blocking occurred significantly and aggregation / sedimentation was observed in the gel using guar gum.

  Since the dispersant of the present invention can improve the anti-blocking property of the resin-coated sand, it can improve the dispersibility when dispersed in a highly viscous gel and can reduce the amount of proppant to be used. Therefore, it can utilize suitably in the hydraulic fracturing method performed by a gas well or an oil well. For example, since the proppant can be efficiently injected into the crack site generated in the shale layer by the hydraulic fracture method, it can be efficiently injected through the high-viscosity gel, so that the amount of proppant can be reduced as compared with the conventional method. .

Claims (5)

  A divalent fatty acid metal salt obtained by reacting a fatty acid alkali compound salt obtained by reacting a monovalent alkali compound with a fatty acid having 8 to 24 carbon atoms and a divalent metal salt in an aqueous solution. A resin-coated sand dispersant for gas or oil wells, characterized by comprising particles. In the fatty acid metal salt particles having a particle size summary value A represented by the following formula (1) of 2.0 or less and allowed to stand for 10 minutes in an environment at 80 ° C., the following formula (2) measured by a powder tester The resin coated sand dispersant for a gas well or oil well according to claim 1, wherein the degree of aggregation B (%) satisfies a relationship of B≤20.

(1) Formula particle size summary value A = (D90−D10) / D50 (where 1.0 ≦ D50 ≦ 40.0)
D10: 10% integrated diameter (μm) of fatty acid metal salt particles based on volume
D50: Median diameter (μm) of fatty acid metal salt particles based on volume
D90: 90% integrated diameter (μm) of fatty acid metal salt particles based on volume

(2) Formula Cohesion B = [(mass of fatty acid metal salt particles remaining on sieve with 350 μm sieve) / 2] × 100 × (1/1) + [(fatty acid metal salt remaining on sieve with 250 μm sieve mesh) Particle Mass) / 2] × 100 × (3/5) + [(Mass of Fatty Acid Metal Salt Particles Remaining on Sieve 150 μm) / 2] × 100 × (1/5)]   When the divalent fatty acid metal salt particles are measured by a flow type particle image analyzer, the average circularity C of a particle group having a particle size of 10% to 90% is 0.810 to 1.000. The resin-coated sand dispersant for gas wells or oil wells according to claim 1 or 2.   The resin-coated sand dispersant for gas wells or oil wells according to any one of claims 1 to 3, wherein the divalent metal constituting the divalent fatty acid metal salt particles is calcium.   A proppant composition comprising the resin-coated sand dispersant for a gas well or oil well according to any one of claims 1 to 4 and the resin-coated sand for a gas well or oil well.