Wettability control agent for rock surfaces and evaluation method therefor

Abstract

[Problem] To provide a wettability control agent for rock surfaces which is able to hydrophilize rock surfaces through conformal coating. [Solution] A wettability control agent for rock surfaces, which hydrophilizes the rock surfaces through conformal coating, the wettability control agent comprising silica particles (a) having a DLS average particle diameter, as determined by the dynamic light scattering method, of 5-200 nm and an aqueous medium (b), wherein at least some of the silica particles are coated with a silane compound (c) having a hydrophilic organic group; a method for controlling the wettability of rock surfaces using the wettability control agent; or a method for evaluating the wettability of a rock surface by utilizing the wettability control agent.

Description

TITLE OF THE INVENTION: WETTABILITY CONTROL AGENT FOR ROCK SURFACES AND EVALUATION METHOD THEREFOR TECHNICAL FIELD

[0001] The present invention relates to a wettability control agent for rock surfaces and an evaluation method therefor, specifically, to a wettability control agent which makes rock surfaces hydrophilic through conformal coating, and a method for evaluating a change in surface wettability (hydrophilicity) caused by the conformal coating using a quartz crystal microbalance (QCM) method. BACKGROUND ART

[0002] Since silica particles have high hardness and heat resistance, they are widely used as modifiers that are incorporated into resins and the like in order to impart hardness and heat resistance to such resins. In addition, in recent years, silica particles have been used in enhanced oil recovery (EOR) flooding for recovering crude oil by performing injection into oil reservoirs in inland or offshore oil fields, and for example, it has been proposed to improve the efficiency of removing crude oil from rock surfaces by incorporating fine particles such as an aqueous silica sol (colloidal silica) into a chemical liquid for crude oil recovery, thereby improving the crude oil recovery rate (Patent Document 1).

[0003] Therefore, recently, more effective methods for improving wettability of rock surfaces have become necessary in order to make fluids in underground bedrock move more smoothly. Improvement in wettability of rock surfaces can contribute not only to fluid movement but also to fluid storage. Incidentally, QCM sensors using crystal resonators are known as sensors for evaluating wettability.

[0004] When a voltage is applied to a crystal resonator, an inverse piezoelectric phenomenon which causes vibrations occurs. In addition, it is known that, when the weight of the crystal resonator part changes due to adhering of a substance to the surface of the crystal resonator or peeling off of an adhered substance, the resonance frequency of the crystal resonator changes. A QCM sensor is a means for measuring the weight and concentration of adhered substances based on this frequency change. Various sensors that utilize these properties of crystal resonators have been proposed so far. For example, in a sensor which detects the concentration of a detection target substance in a mixed solution obtained by dissolving a predetermined detection target substance in a predetermined solvent, a concentration sensor that includes a crystal resonator whose natural frequency changes according to a change in the concentration of the detection target substance and an oscillation circuit that oscillates the crystal resonator has been disclosed in which the crystal resonator is impregnated into the mixed solution and oscillated, the natural frequency of the crystal resonator at that time is determined, and thus the concentration of the detection target substance in the mixed solution is determined (Patent Document 1). Prior Art Documents Patent Documents

[0005] Patent Document 1: WO 2019 / 054414 Patent Document 2: Japanese Unexamined Patent Application Publication No. H06-018394 SUMMARY OF THE INVENTION Problem to be Solved by the Invention

[0006] The present invention provides a wettability control agent for rock surfaces, which can make rock surfaces hydrophilic through conformal coating. In addition, the present invention provides, in addition to the wettability control agent for rock 3 surfaces, a method for controlling wettability of rock surfaces using the same and a method for evaluating wettability of rock surfaces by applying the wettability control agent. Means for Solving the Problem

[0007] The present invention provides, as a first aspect, a wettability control agent for rock surfaces, which makes rock surfaces hydrophilic through conformal coating, comprising silica particles (a) having a DLS average particle diameter of 5 to 200 nm, which is determined by a dynamic light scattering method, and an aqueous medium (b), wherein at least some of the silica particles are coated with a silane compound (c) having a hydrophilic organic group, as a second aspect, the wettability control agent for rock surfaces according to the first aspect, wherein the hydrophilic organic group is an epoxy group-containing organic group, an amino group-containing organic group, a hydroxy group-containing organic group, or a carboxy group-containing organic group, as a third aspect, the wettability control agent for rock surfaces according to the first aspect or the second aspect, wherein, in a test method in which a sensor in which an electrode layer and a quartz layer are laminated on a crystal resonator is made to resonate in a medium containing brine containing calcium ions and magnesium ions and the wettability control agent for rock surfaces, a value (F3) obtained by subtracting a AF value (F2) indicating a change in weight of an accumulation layer containing a silica component accumulated on a surface of the sensor from the start of resonance to 12,000 seconds from a AF value (Fl) indicating a change in weight of the accumulation layer containing the silica component accumulated on the surface of the sensor from the start of resonance to 2,000 seconds is 20 to 20 when resonance frequency of the crystal resonator is 25 MHz, as a fourth aspect, the wettability control agent for rock surfaces according to any one of the first aspect to the third aspect, wherein, in evaluation of wettability of rock surfaces in which a crude oil with a volume of 0.01 to 1 pl is brought into contact with a bottom of a rock slab in brine containing the wettability control agent for rock surfaces, a contact angle between an outer surface of a droplet of the crude oil and the rock slab is reduced by 3° or more compared to the contact angle evaluated in brine not containing the wettability control agent, as a fifth aspect, the wettability control agent for rock surfaces according to the third aspect or the fourth aspect, wherein the brine is brine containing sodium ions and having a salt concentration of 0.1 to 30% by mass, as a sixth aspect, the wettability control agent for rock surfaces according to the third aspect, wherein the resonance frequency of the crystal resonator is in a range of 1 MHz to 100 MHz, as a seventh aspect, the wettability control agent for rock surfaces according to the first aspect, wherein the wettability control agent is a wettability control agent for storing a fluid in bedrocks or securing a flow path in bedrocks, as an eighth aspect, the wettability control agent for rock surfaces according to the seventh aspect, wherein the fluid is a gas or liquid containing carbon dioxide, a waterbased fluid, or a water-based fluid containing fine rock particles with a size of 10 pm or less, as a ninth aspect, a method for controlling wettability of rock surfaces, comprising controlling the wettability control agent for rock surfaces according to any one of the first aspect to the eighth aspect such that a silica particle concentration is 0.1 to 30% by mass in an aqueous medium, and applying the wettability control agent to rock surfaces, and as a tenth aspect, a method for evaluating wettability of rock surfaces, comprising bringing a crude oil with a volume of 0.01 to 1 pl into contact with a bottom of a rock slab in brine containing the wettability control agent for rock surfaces according to any one of the first aspect to the third aspect, and evaluating a contact angle between an outer surface of a droplet of the crude oil and the rock slab. Effects of the Invention

[0008] The wettability control agent for rock surfaces of the present invention can make rock surfaces hydrophilic through conformal coating. In addition, since the wettability control agent for rock surfaces of the present invention has excellent salt resistance, it can be used for rock surfaces in a brine environment. Therefore, for example, the wettability control agent can be injected into underground bedrock in a brine environment without aggregation, and it is expected that the bedrock surface will be hydrophilized through conformal coating. Accordingly, it is expected that a flow path for a hydrophilic fluid will be secured without causing a risk of formation blockage, which is expected to contribute to storage of a hydrophobic fluid and to exhibit an effect of peeling off a crude oil and the like from the rock surface. In addition, according to the wettability evaluation method of the present invention, it is possible to evaluate the wettability of the rock surfaces to which the wettability control agent is imparted. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [FIG. 1] FIG. 1 is a diagram showing the measurement results of a frequency change value AF value indicating a change in weight (change in weight of an accumulation layer containing a silica component) detected by a QCM sensor in Example 1, Example 2 and Example 3 (test fluids 1 to 3). [FIG. 2] FIG. 2 is a diagram showing the measurement results of a frequency change value AF value indicating a change in weight (change in weight of an accumulation layer containing a silica component) detected by a QCM sensor in Example 7, Example 8, Example 9 and Example 10 (test fluids 4 to 7). [FIG. 3] FIG. 3 is a diagram showing the measurement results of a frequency change value AF value indicating a change in weight (change in weight of an accumulation layer containing a silica component) detected by a QCM sensor in Comparative Example 1 and Comparative Example 2 (test fluids 8 and 9). [FIG. 4] FIG. 4 shows a schematic view of a three-phase contact angle measurement (FIG. 4(A)) and a schematic view of wettability (FIG. 4(B)). [FIG. 5] FIG. 5 is a diagram showing the shapes of crude oil droplets used for measuring a contact angle (a) obtained with test fluids of Examples 1 to 3, Comparative 6 Example 1, and Examples 7 to 10 (test fluids 1 to 3, 8, and 4 to 7) in evaluation-1 regarding change in wettability of a substrate (Berea sandstone) in a liquid dispersion medium and the shape of a blank (contact angle (b)) crude oil droplet. [FIG. 6] FIG. 6 is a diagram showing the shape of a crude oil droplet used for measuring a contact angle (a) obtained with a test fluid of Example 4 (test fluid 1) in evaluation-2 regarding change in wettability of a substrate (calcite) in a liquid dispersion medium, and the shape of a blank (contact angle (b)) crude oil droplet. [FIG. 7] FIG. 7 is a diagram showing the shapes of crude oil droplets used for measuring a contact angle (a) obtained with test fluids (test fluids 1 and 2) of Example 5 and Example 6 in evaluation-3 regarding change in wettability of a substrate (slide glass) in a liquid dispersion medium, and the shape of a blank (contact angle (b)) crude oil droplet. MODES FOR CARRYING OUT THE INVENTION

[0010] [Wettability control agent for rock surfaces] The present invention relates to a wettability control agent for rock surfaces, which makes rock surfaces hydrophilic through conformal coating (hereinafter simply referred to as a wettability control agent).

[0011] When nanoparticles are adsorbed onto a substrate for coating, adsorption of the particles onto the substrate may continue, including aggregation of the particles until the supply of nanoparticles is interrupted. While this is expected to increase the thickness of the layer coated with nanoparticles and impart better nanoparticle performance, it is undesirable, for example, when coating with nanoparticles is performed on a narrow flow path and the like because this can lead to blockage of the flow path. In the coating with the wettability control agent according to the present invention, as will be described below, the results suggest that, although nanoparticles (silica particles) are adsorbed onto the rock surfaces, the amount of adsorption thereof reaches saturation at a certain level, and even if the nanoparticles are subsequently supplied, hardly any further adsorption occurs. That is, the conformal coating in the present invention refers to coating in which the amount of adsorption reaches saturation at a certain level, for example, coating in which a coating agent (wettability control agent) is adsorbed onto the surface in a substantially uniform and thin layer such as a monomolecular layer. Examples of rocks that can be hydrophilized with the wettability control agent of the present invention include sedimentary rocks and igneous rocks, and examples of sedimentary rocks include conglomerates, sandstones, siltstones, mudstones, limestones, carbonate rocks, and cherts, and examples of igneous rocks include basalts, andesites, dacites, rhyolites, dolerites, porphyrites, quartz porphyry, gabbros, diorite, and granite. In addition, minerals constituting these rocks (quartz, calcite, olivine, pyroxene, amphibole, mica, feldspar, etc.), glass and the like can also be targets to be hydrophilized with the wettability control agent of the present invention, and for the sake of convenience, in the present invention, these are also treated as rocks in the broad sense.

[0012] The wettability control agent of the present invention contains silica particles (a) having a DLS average particle diameter of 5 to 200 nm, which is determined by a dynamic light scattering method, and an aqueous medium (b). Here, at least some of the silica particles (a) are coated with a silane compound (c) having a hydrophilic organic group.

[0013] As an embodiment of the silica particles (a) and the aqueous medium (b), for example, an aqueous silica sol can be used. The aqueous silica sol refers to a colloidal dispersion system containing an aqueous solvent (that is, the aqueous medium (b)) as a dispersion medium and colloidal silica particles (that is, the silica particles (a)) as dispersoids, and can be produced by a known method using water glass (sodium silicate aqueous solution) as a raw material.

[0014] In the present invention, the average primary particle diameter of the silica particles (a) may be, for example, 5 to 100 nm. As described above, the average primary particle diameter of the aqueous silica sol, which is an example of the embodiment of the silica particles (a) and the aqueous medium (b), is the average primary particle diameter of colloidal silica particles that are dispersoids. In the present invention, unless otherwise specified, the average primary particle diameter of the aqueous silica sol (colloidal silica particles) refers to a specific surface area diameter or Sears method particle diameter obtained by measurement by a nitrogen adsorption method (BET method). The specific surface area diameter (average particle diameter (specific surface area diameter) D (nm)) obtained by measurement by the nitrogen adsorption method (BET method) is obtained by the formula D (nm) = 2720 / S from the specific surface area S (m2 / g) measured by the nitrogen adsorption method. The Sears method particle diameter refers to an average particle diameter measured based on a rapid method for measuring the colloidal silica particle diameter with reference to G. W. Sears, Anal. Chern. 28 (12) p. 1981, 1956. Specifically, it is an equivalent diameter (specific surface area diameter) calculated from the specific surface area of colloidal silica determined from the amount of 0.1 N-NaOH required to titrate colloidal silica equivalent to 1.5 g of SiO2 from a pH of 4 to a pH of 9. In the present invention, the average primary particle diameter of the silica particles (a), that is, for example, an aqueous silica sol (colloidal silica particles), determined by the nitrogen adsorption method (BET method) or the Sears method, is, for example, 5 to 100 nm, and may be, for example, 5 to 70 nm, 5 to 60 nm, 5 to 50 nm, or 5 to 30 nm.

[0015] In the present invention, for the silica particles (a) in the aqueous medium (b), that is, the silica particles (a) in a wettability control agent or the silica particles (a) in a fluid sample obtained by mixing a wettability control agent with brine or the like, it is possible to determine the average particle diameter (DLS average particle diameter) and the dispersed state (whether the silica particles are in a dispersed state or an aggregated state) by measurement by the dynamic light scattering method. The DLS average particle diameter refers to an average value of secondary particle diameters (dispersed particle diameters), and it can be said that the DLS average particle diameter when completely dispersed is about twice the average primary particle diameter (which indicates a specific surface area diameter obtained by measurement by the nitrogen adsorption method (BET method) or the Sears method, and an average value of primary particle diameters). Here, as the DLS average particle diameter increases, it can be determined that the silica particles in the medium are in an increasingly aggregated state. For example, as an example of the aqueous silica sol, the aqueous silica sol (Snowtex (registered trademark) ST-O, commercially available from Nissan Chemical Corporation) has an average particle diameter (BET method) of 10 to 11 nm and a DLS average particle diameter of 15 to 20 nm. As shown in examples to be described below, a silica sol (wettability control agent) of a synthesis example prepared using this aqueous silica sol and a test fluid (salt resistance sample) containing this sol have a DLS average particle diameter of 25 nm or less, and this result indicates that the silica particles are almost in a dispersed state in the medium. In the present invention, the average particle diameter (DLS average particle diameter) of the silica particles (a) is 5 to 200 nm, and may be, for example, 5 to 100 nm, 1 to 100 nm, 5 to 50 nm, 5 to 30 nm, 5 to 15 nm, or 5 to 70 nm. By making particles have a DLS average particle diameter of more than 5 nm, the particles do not aggregate in the aqueous silica sol and become more stable, and by making particles have an average particle diameter of less than 200 nm, for example, the particles easily enter narrow flow paths such as pores in sandstones or carbonate rocks present in underground oil field layers.

[0016] In addition, when particles have a DLS average particle diameter of more than 200 nm, there is a risk of the particles not entering the above narrow flow path and blocking the path. Therefore, when considering applications to such narrow flow paths, it is preferable to use an aqueous silica sol that does not contain coarse particles, for example, a silica sol in which the cumulative particle size distribution D90 of the average particle diameters (DLS average particle diameters) of silica particles, determined by a dynamic scattering method, is 5 to 200 nm, for example, 5 to 150 nm, or for example, 5 to 100 nm, or for example, 5 to 70 nm. The D90 is a particle diameter of cumulative 90% from the side of fine particles in a cumulative particle size distribution. In the present invention, for example, the value of the cumulative particle size distribution can be measured by particle size distribution by image analysis. In the measurement of particle size distribution by image analysis, the measurement sample is analyzed as a transmission electron microscope image. Analysis methods for the D value include a number distribution method and a volume distribution method. In the number distribution method, particles are regarded as perfect circles having the same area as the particles, and the percentage of particles having a specific particle diameter within a certain field of view is measured. In addition, in the volume distribution method, assuming that the volume and the weight are proportional if the density of the particles is constant, the mass percentage of particles having a specific particle diameter in a certain amount of a sample is measured. In the present invention, it is preferable to obtain the D value (D90) by the volume distribution method.

[0017] Commercially available aqueous silica sols can be used. In addition, an aqueous silica sol with a silica concentration of 5 to 50% by mass is generally commercially available, and is preferable because it is readily available. In addition, the aqueous silica sol includes an alkaline aqueous silica sol and an acidic aqueous silica sol. Although both can be used, the acidic aqueous silica sol is preferably used. Examples of commercially available acidic aqueous silica sols include Snowtex (product name) ST-OXS, ST-OS, ST-O, and ST-OL.

[0018] In the wettability control agent of the present invention, at least some of the silica particles (a) are coated with a silane compound (c) having a hydrophilic organic group.

[0019] Here, in the present invention, “coated with a silane compound” refers to an embodiment in which the surface of the silica particles is coated with a silane compound and also includes any embodiment in which a silane compound is bonded to the surface of the silica particles. “An embodiment in which the surface of the silica particles is coated with a silane compound” may refer to an embodiment in which at least a part of the surface of the silica particles is coated with a silane compound, that is, includes an embodiment in which the silane compound covers a part of the surface of the silica particles and an embodiment in which the silane compound covers the entire surface of the silica particles. In this embodiment, it is not important whether or not the silane compound is bonded to the surface of the silica particles. In addition, “an embodiment in which a silane compound is bonded to the surface of the silica particles” may refer to an embodiment in which the silane compound is bonded to at least a part of the surface of the silica particles, that is, includes an embodiment in which the silane compound is bonded to a part of the surface of the silica particles, an embodiment in which the silane compound is bonded to a part of the surface of the silica particles and covers at least a part of the surface, and also an embodiment in which the silane compound is bonded to the entire surface of the silica particles and covers the entire surface.

[0020] The silane compound (c) may be a silane compound having, as a hydrophilic organic group, for example, an epoxy group-containing organic group, an amino group-containing organic group, a hydroxy group-containing organic group, or a carboxy group-containing organic group. In addition, the silane compound (c) preferably has, in addition to the hydrophilic organic group, for example, a hydrolyzable group such as an alkoxy group, an acyloxy group, or a halogen group.

[0021] Specific examples of these silane compounds (c) include silane coupling agents having an epoxy group-containing organic group, an amino group-containing organic group, or an acid anhydride-containing organic group with a protected carboxy group. Examples of silane coupling agents having an epoxy group-containing organic group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 2-(3,4-epoxy cy cl ohexyl)propyltri ethoxy silane, 2-(3,4-epoxycy cl ohexyl)ethyltrimethoxy silane, 2-(3,4-epoxycyclohexyl)ethyltri ethoxy silane, 2-(3,4-epoxycyclohexyl)methyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyltriethoxysilane, 1-(3,4-epoxycy cl ohexyl)methyltrimethoxysilane, and 1-(3,4- epoxy cyclohexyl)methyltriethoxysilane. In addition, examples of silane coupling agents having an amino group-containing organic group include 3-(2-(2-aminoethylamino)ethylamino)propyltri ethoxy silane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrichlorosilane, 3-aminopropyltrimethoxy silane, 3-aminopropyltri ethoxy silane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-tri ethoxy silyl-N-(l,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl -3 -ami nopropy Itri ethoxy sil ane. In addition, examples of acid anhydride-containing silane coupling agents include [3-(trimethoxysilyl)propyl]succinic anhydride.

[0022] In the present invention, the silica particles of which at least some are coated with a silane compound having a hydrophilic organic group (also referred to as “silica particles whose surface is treated with a silane compound”) can be obtained, for example, by adding a silane compound to an aqueous silica sol and then performing heating at 50 to 100°C for about 1 hour to 20 hours. In this case, the amount of the silane compound added with respect to the silica particles (silica solid content) in the aqueous silica sol can be set to, for example, a mass ratio of silane compound / silica particles = 0.1 to 10.0, or for example, 0.1 to 5.0, 0.1 to 2.0, or 0.1 to 1.0. In addition, for example, the silane compound can be added in an amount such that the amount of silane compound added (molecules / nm2) per 1 nm2 of the surface of the silane particles is about 0.5 to 50 molecules, 1.0 to 20 molecules, or 2.0 to 10 molecules. The amount of surface treated with the silane compound, that is, the amount of the silane compound bonded to the surface of the silica particles is preferably, for example, about 0.1 to 12 molecules, 0.1 to 8 molecules, 0.1 to 4 molecules, 0.3 to 4 molecules, 0.5 to 4 molecules, or 0.5 to 3 molecules per 1 nm2 of the surface of the silica particles.

[0023] As described above, when the wettability control agent of the present invention is applied to a rock surface, nanoparticles (silica particles) are adsorbed onto the rock surface, but the amount of adsorption reaches saturation at a certain level, and a substantially uniform and thin layer is formed (conformal coating). Whether the rock surface is conformally coated with the wettability control agent of the present invention can be checked by a measurement method using a QCM method.

[0024] The QCM method is a method of measuring the mass change on the nanogram order from a change in resonance frequency of a crystal resonator, specifically, a method with which the amount of adsorption of a substance onto a surface of a sensor (QCM sensor) including a crystal resonator can be measured at the nanogram level in real time. In measurement using a QCM sensor, the change in weight can be measured from the frequency change value, AF value. That is, if the AF value is corrected to zero when the QCM sensor is brought into contact with a blank solution containing no agent, etc. (external stimuli), the AF value changes to negative when the substance is adsorbed onto the sensor, and the AF value changes to positive if the substance is desorbed.

[0025] In the present invention, a sensor in which an electrode layer and a quartz layer are laminated on a crystal resonator is made to resonate in a medium containing brine and the wettability control agent according to the present invention, and utilizing the fact that the resonance frequency of the crystal resonator changes when the silica particles (contained in the wettability control agent) are adsorbed onto or desorbed from (or adhered to or peeled off from) the quartz layer, the amount of change is monitored to measure a change in a physical quantity (change in weight). The brine contains calcium ions and magnesium ions, and for example, brine containing sodium ions as a main component and having a salt concentration of 0.1 to 30% by mass can be preferably used. The crystal resonator in a resonance frequency range of 100 Hz to 100 MHz, typically 1 MH to 100 MHz, can be used.

[0026] More specifically, a sensor in which an electrode layer and a quartz layer are laminated on a crystal resonator is made to resonate in a medium containing brine containing sodium ions as a main component and containing calcium ions and magnesium ions and the wettability control agent for rock surfaces, and AF value indicating a change in frequency (change in weight) of an accumulation layer containing a silica component accumulated on the surface of the sensor is monitored. The AF value is zero-corrected with the value obtained in advance using only the brine (blank solution). The sensor uses a crystal resonator with a diameter of about 15 mm, and can be used for measurement by resonating the crystal resonator, for example, at a resonance frequency of about 25 MHz.

[0027] In the present invention, the amount of change in the AF value from 2,000 seconds to 12,000 seconds after the start of resonance is observed. Then, the amount of change (difference) (F3) is calculated by subtracting the AF value (F2) indicating a change in weight of an accumulation layer containing a silica component accumulated on the surface of the sensor from the start of resonance to 12,000 seconds from the AF value (Fl) indicating a change in weight of an accumulation layer containing a silica component accumulated on the surface of the sensor from the start of resonance to 2,000 seconds. When the change in the F3 value, that is, the AF value during the observation period, is within a certain range, for example, when the resonance frequency of the crystal resonator is 25 MHz, if the change in the AF value is within ±20, for example, F3 is -20 to 15, -20 to 10, -10 to 20, -5 to 20, -5 to 15, -3 to 12, 0 to 15, or 0 to 20, and the weight does not change significantly, it can be determined that the amount of silica particles adsorbed onto the surface of the sensor (quartz layer) is saturated or nearly saturated (silica particles do not aggregate and become saturated in adsorption state of a certain level), that is, it is determined that a conformal coating (nanoparticles (silica particles) are adsorbed on the rock surface, but the amount of adsorption reaches saturation at a certain level, and a substantially uniform and thin layer is formed) is formed. Because the weight of the accumulation layer containing a silica component on the surface of the sensor is expected to vary slightly (increase or decrease) depending on the surrounding environment, even if the F3 value indicating weight loss is a negative value, when the value is small (-20 to 0, or -10 to 0, etc.), it can be considered that the value is within the range of variation, that is, the conformal coating is maintained. In the change from 2,000 seconds to 12,000 seconds after the start of resonance, adhering to the surface of the substrate occurs at 0 seconds 15 immediately after resonance, the conformal coating is completed at around 2,000 seconds, and if additional aggregates accumulate thereafter, the AF value decreases (excessive adsorption occurs). Thus, this tendency continues even after 12,000 seconds.

[0028] The hydrophilization of rock surfaces (wettability of rock surfaces) by the wettability control agent of the present invention can be evaluated by measurement of a contact angle between a solid and a liquid (or gas) within a liquid, so-called three-phase contact angle measurement. Particularly, in the present invention, as the method for evaluating wettability of rock surfaces, a method in which, in brine containing the wettability control agent according to the present invention, a predetermined amount of a crude oil is brought into contact with (adhered to) the bottom of a rock slab, and the contact angle between the outer surface of the crude oil droplet and the rock slab is measured can be used.

[0029] In the present invention, the three-phase contact angle measurement can be performed using, for example, a device shown in FIG. 4 (schematic view). As shown in FIG. 4(A), a device 1 includes an external cell 2, a substrate 3 installed at a predetermined distance from the bottom of the external cell 2, and a capillary needle 4 capable of discharging a fluid to the side under the substrate (the side facing the bottom of the external cell). In the measurement, the external cell 2 is filled with the surrounding liquid 5 (brine (blank), a liquid containing the wettability control agent of the present invention, etc.) so that the substrate 3 (for example, a rock slab such as Berea sandstone) installed in the external cell 2 (quartz cell, etc.) is sufficiently immersed, the capillary needle 4 (made of glass, etc.) is filled with a crude oil (not shown), a predetermined amount (for example, a volume of 0.01 to 1 pl) of the crude oil is then discharged toward the substrate in the surrounding liquid, and the formed crude oil droplet d is observed. FIG. 4(B) shows an enlarged portion of the substrate 3 and the formed crude oil droplet d, and is a schematic view of wettability. As shown in this figure, when the contact angle 0 of the crude oil droplet d formed is larger with respect to the substrate 3, the sample becomes more hydrophobic (oil wettability: FIG. 4(B)(i)), and when the contact 16 angle 9 is smaller, the sample becomes more hydrophilic (water wettability: FIG. 4(B)(ii)). Generally, a contact angle of less than 50° can be evaluated as having strong water wettability, a contact angle of 50° or more and less than 70° can be evaluated as having weak water wettability, and a contact angle of 70° or more and less than 110° can be evaluated as having intermediate water wettability.

[0030] As the wettability control agent according to the present invention, a wettability control agent in which, in evaluation of wettability of rock surfaces in which a crude oil with a volume of 0.01 to 1 pl is brought into contact with (adhered to) the bottom of the rock slab in brine containing the wettability control agent, the contact angle between the outer surface of the crude oil droplet and the rock slab can be reduced by 3° or more, for example, 3° to 90°, 3° to 70°, 3° to 50°, 3° to 40°, 3° to 30°, or 5° to 30°, compared to the contact angle in evaluation in which a crude oil is similarly brought into contact with the bottom of the rock slab in brine not containing the wettability control agent is preferable. As the brine to be used for the measurement, brine containing calcium ions and magnesium ions, for example, containing sodium ions as a main component, and having a salt concentration of 0.1 to 30% by mass can be preferably used.

[0031] As described above, the wettability control agent of the present invention can conformally coat the rock surface and make it hydrophilic, and is therefore useful as a wettability control agent for storing fluids in bedrocks or securing flow paths in bedrocks. In this case, the fluid may be, for example, a gas or liquid containing carbon dioxide, a water-based fluid, or a water-based fluid containing fine rock particles with a size of 1 pm or less.

[0032] In addition, the present invention also provides a method for controlling wettability of rock surfaces, including controlling the wettability control agent for rock surfaces to a silica particle concentration of 0.1 to 30% by mass, 0.1 to 20% by mass, or 0.1 to 10% by mass in an aqueous medium and applying it to the rock surfaces. The wettability control agent of the present invention can be arbitrarily diluted with an aqueous medium such as brine or river water to set the silica particle concentration to 17 0.1 to 30% by mass, 0.1 to 20% by mass, or 0.1 to 10% by mass, and then used to treat the rock surface. For example, when the rock is an underground rock, the wettability can be controlled by injecting the agent into the underground bedrock using an underground injection well pipe to coat the rock surface.

[0033] In addition, the present invention also provides a method for evaluating wettability of rock surfaces, including bringing a crude oil with a volume of 0.01 to 1 pl into contact with (adhered to) the bottom of a rock slab in brine containing the wettability control agent for rock surfaces and evaluating the contact angle between the outer surface of the crude oil droplet and the rock slab. Examples

[0034] The present invention will be described below in more detail with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to these examples.

[0035] (Measurement devices) Evaluation of test fluids 1 to 9 containing the wettability control agents (aqueous silica sols prepared in synthesis examples, etc.) used in examples and comparative examples (amount of silica particles in the test fluid adsorbed onto the substrate, and change in wettability of the substrate with the test fluid) and physical properties (DLS average particle diameter) of the test fluids 1 to 9, and evaluation of physical properties of the wettability control agent (DLS average particle diameter, D90, pH, electrical conductivity, and viscosity) were performed using the following devices. ■The amount of silica particles adsorbed onto the substrate: a QSence Analyzer (product name, commercially available from Biolin Sientific) was used. •Wettability of a substrate with a test fluid: a contact angle meter (product name DM 500, commercially available from Kyowa Interface Science Co., Ltd.) was used. •DLS average particle diameter (dynamic light scattering method particle diameter): a dynamic light scattering method particle diameter measurement device (product name Zetasizer Nano, commercially available from Spectris Co., Ltd., Malvern Division) was used. •D90: the diameter of particles whose frequency was 90% in the particle volume distribution detected by a dynamic light scattering method particle diameter measurement device (product name Zetasizer Nano, commercially available from Spectris Co., Ltd., Malvern Division) was used. • Silica specific surface area: calculated from the amount of nitrogen gas adsorption measured using MONOSORB (product name, commercially available from Quantachrome Instruments). pH: a pH meter (commercially available from DKK-TOA Corporation) was used. •Electrical conductivity: an electrical conductivity meter (commercially available from DKK-TOA Corporation) was used. •Viscosity: a BMII type viscometer (product name, commercially available from Tokyo Keiki Inc.) was used.

[0036] (Removal of silane not bonded to silica particles) 2 g of the aqueous silica sol prepared in the synthesis example to be described below and 4 g of pure water were put into a 15 ml centrifugal filter unit (product name Amicon Ultra-15, commercially available from Merck), and centrifuged at a centrifugal force of 2770G for 20 minutes. After centrifugation, the liquid discharged from the bottom of the unit was discarded, the same mass of pure water as the discarded liquid was put into the aqueous silica sol concentrated on the filter, and the mixture was re-dispersed, and then centrifuged again at a centrifugal force of 2770G for 20 minutes. The above procedure was repeated a total of four times to obtain an aqueous silica sol from which a silane not bonded to the silica particles had been removed.

[0037] (Measurement of silica specific surface area) The aqueous silica sol or the aqueous silica sol from which a silane not bonded to the silica particles had been removed was dried on a hot plate at 80°C, the obtained silica gel was crushed in a mortar and then additionally dried under vacuum at 60°C for 3 hours to obtain a dry silica powder. The specific surface area (m2 / g) of the powder was measured by the nitrogen adsorption method based on the BET theory (BET method, that is, nitrogen gas BET method).

[0038] (Measurement of amount of silane bonds) Using the above procedure, the aqueous silica sol from which the silane not bonded to the silica particles had been removed was heated and dried at 100°C and crushed in a mortar to obtain a silica sol powder. The carbon content of the obtained silica sol powder was measured using an organic trace element metal analysis device, and the amount of silane bonds (amount of surface treatment) was calculated from the obtained carbon content by the following formula. Amount of surface treatment = (Cm Cn Sc * A) / (Ct x Cs) In the formula, Cm is the carbon content, Cn is the carbon molecular weight, Sc is the number of carbon atoms in the silane, A is the Avogadro’s number, Ct is the silica particle mass, and Cs is the silica specific surface area. Here, the unit of amount of silane bonds obtained from the above carbon content measurement was (molecules / nm2).

[0039] (Evaluation-1 regarding amount of adsorption onto substrate) A standardized used quartz deposition sensor (commercially available from Biolin Sientific) was prepared (product number: QSX303, a sensor in which a silicon dioxidecontaining film was formed on a gold electrode on a crystal resonator, and the crystal resonator had a diameter of 15 mm). The sensor was immersed in pure water, and ultrasonic waves with irradiation frequencies of 33 kHz and 40 kHz were irradiated every minute using a US CLEANER (commercially available from As One Corporation), and irradiated for a total of 10 minutes. After the irradiation, the sensor was removed from pure water, and rinsed with tetrahydrofuran. The rinsed sensor was immersed in toluene and two types of ultrasonic waves were irradiated again for 10 minutes in the same manner as above. Then, the sensor was removed from toluene and immersed in tetrahydrofuran, and two types of ultrasonic waves were then irradiated again for 10 minutes in the same manner as above. After the irradiation, the sensor was removed from tetrahydrofuran and dried on a hot plate at 100°C for 5 minutes. The sensor was set in a QCM-D chamber, and pure water was sent into the chamber 20 at a flow rate of 0.1 mL / min through a flow path with a total length of 100 cm on the inlet and outlet sides. After confirming that there was no change in the frequency change value (Frequency, AF value) using QCM-D, brine with a salt concentration of 4% by mass was sent at a flow rate of 0.1 mL / min. Here, the brine contained 2.4% by mass of sodium chloride, 1% by mass of magnesium chloride, 0.1% by mass of calcium chloride, and 0.5% by mass of other salt components. After confirming that there was no change in the AF value in the same manner as above, a test fluid to be described below was sent at a flow rate of 0.1 mL / min, and brought into contact with the sensor. The AF value detected by the sensor was quantified according to the interaction caused by contact between the quartz on the sensor and the test fluid. FIG. 1 to FIG. 3 show changes in AF (frequency change value) detected when the resonance frequency of the crystal resonator was 25 MHz over time after the test fluid reached the sensor. Here, when the AF value was measured, zero-correction was performed using brine (blank solution) with a salt concentration of 4% by mass. Table 1 and Table 2 show the F value (Fl) at 2,000 seconds and the AF value (F2) at 12,000 seconds from the start of resonance, and the difference F3 (amount of change: Fl - F2) between these AF values. In addition, the amount of adsorption was evaluated using the F3 value according to the following determination criteria. Table 1 and Table 2 also show the evaluation results of the amount of adsorption. <Determination of amount of adsorption> (F3 value) A: the AF value was a negative value compared to the start of resonance, and the value (F3) obtained by subtracting the AF value (F2) at 12,000 seconds from the AF value (Fl) at 2,000 seconds was -0 or more and less than 20. B: the AF value was a negative value compared to the start of resonance, and the value (F3) obtained by subtracting the AF value (F2) at 12,000 seconds from the AF value (Fl) at 2,000 seconds was -30 or more and less than -20, or 20 or more and less than 30. C: the AF value was a negative value compared to the start of resonance, and the value (F3) obtained by subtracting the AF value (F2) at 12,000 seconds from the AF value (Fl) at 2,000 seconds was less than -30 or 30 or more. The adsorption evaluation results based on the above determination indicate that A was the most preferable result, followed by B and C. Here, the resonance frequency of the crystal resonator at which the AF value was observed was 25 MHz.

[0040] (Evaluation-1 regarding change in wettability of substrate) Evaluation-1 regarding change in wettability was performed by three-phase contact angle measurement. A three-phase kit used in the three-phase contact angle measurement was a three-phase kit (145 mL) (commercially available from Kyowa Interface Science Co., Ltd.), a Berea sandstone was used as the substrate, a glass capillary needle was used as the needle, and a crude oil was used as the discharged liquid. As the Berea sandstone sample, a sample with a length of 7.0 cm, a width of 2.8 cm, and a height of 0.5 cm dried at 60°C for 1 day was used. As the glass capillary needle, a needle with a capillary q>50 pm (straight) (commercially available from Kyowa Interface Science Co., Ltd.) bent by an alcohol lamp was used. The crude oil used was Light Sour Russian Urals REBCO Crude Oil (commercially available from ONTA) (refer to the schematic view of the three-phase contact angle measurement shown in FIG. 4(A), and as shown in the schematic view of wettability in FIG. 4(B), when the contact angle 9 between the substrate and the crude oil droplet was larger, the sample became more hydrophobic (oil wettability: FIG. 4(B)(i)), and when the contact angle 9 was smaller, the sample became more hydrophilic (water wettability: FIG. 4(B)(ii))). The Berea sandstone sample was immersed in the brine with a salt concentration of 4% by mass (refer to the above (evaluation-1 regarding amount of adsorption onto substrate), the same applies hereinafter) in a vacuum container, the pressure inside the container was reduced using a vacuum pump, and the Berea sandstone sample was saturated with brine with a salt concentration of 4% by mass, then set in a three-phase kit, and installed in a quartz cell. Then, the quartz cell was filled with a test fluid. After the glass capillary needle was filled with a crude oil, the oil was discharged to the Berea sandstone sample in the test fluid, and the contact angle (a) was calculated from the angle of the formed oil droplets (crude oil droplets). Here, in consideration of the change in shape of oil droplets, the operation from discharging oil droplets to calculating the angle was performed within 1 hour. A Berea sandstone sample prepared in the same procedure was set in a three-phase kit and installed in a quartz cell, the quartz cell was then filled with the brine with a salt concentration of 4% by mass, and the same operation was performed to calculate the contact angle (b) (blank). Table 1 and Table 2 show the volume (discharge amount: pL) of the formed crude oil droplets, and the contact angle (a), the contact angle (b) (blank), and the value of [contact angle (b) - contact angle (a)] in the test fluids. In addition, FIG. 5 shows the shapes of crude oil droplets used for measuring the contact angle (a) obtained with the test fluids in examples and comparative examples and the shape of a blank (contact angle (b)) crude oil droplet. When the contact angle (a) was smaller than the contact angle (b) and the value obtained by subtracting the contact angle (a) from the contact angle (b) [contact angle (b) -contact angle (a)] was larger, the Berea sandstone sample substrate became more hydrophilic with the test fluid.

[0041] (Evaluation-2 regarding change in wettability of substrate) Evaluation-2 regarding change in wettability was performed using the same device and procedure as in evaluation-1 regarding change in wettability except that calcite was used as the substrate. As a calcite sample, Omoshiroi Ishi (Interesting Stone): Calcite (product name, commercially available from Kenis Ltd.) was used. The calcite sample was immersed in the brine with a salt concentration of 4% by mass in a vacuum container, and set in a three-phase kit, and installed in a quartz cell. Then, the quartz cell was filled with a test fluid. After the glass capillary needle was filled with a crude oil, the oil was discharged to the calcite sample in the test fluid, and the contact angle (a) was calculated from the outer angle of the formed oil droplet. The obtained results are shown in Table 1 and FIG. 6. Here, in consideration of the change in shape of oil droplets, the operation from discharging oil droplets to calculating the angle was performed within 1 hour. The quartz cell was filled with the brine with a salt concentration of 4% by mass, and when the contact angle (a) was smaller than the contact angle (b) obtained by performing the same operation and when the value obtained by subtracting the contact angle (a) from the contact angle (b) [contact angle (b) - contact angle (a)] was larger, the calcite sample substrate became more hydrophilic with the test fluid.

[0042] (Evaluation-3 regarding change in wettability of substrate) Evaluation-3 regarding change in wettability was performed using the same device and procedure as in evaluation-1 regarding change in wettability except that slide glass was used as the substrate. As a slide glass sample, White Edge Grinding Frost No. 1 (product name, commercially available from Matsunami Glass Ind., Ltd.) was used. The slide glass sample was ozone-treated in a vacuum container, then immersed in the brine with a salt concentration of 4% by mass, set in a three-phase kit, and installed in a quartz cell. Then, the quartz cell was filled with a test fluid. After the glass capillary needle was filled with a crude oil, the oil was discharged to the slide glass sample in the test fluid, and the contact angle (a) was calculated from the outer angle of the formed oil droplet. The obtained results are shown in Table 1 and FIG. 7. Here, in consideration of the change in shape of oil droplets, the operation from discharging oil droplets to calculating the angle was performed within 1 hour. The quartz cell was filled with the brine with a salt concentration of 4% by mass, and when the contact angle (a) was smaller than the contact angle (b) obtained by performing the same operation and when the value obtained by subtracting the contact angle (a) from the contact angle (b) [contact angle (b) - contact angle (a)] was larger, the slide glass sample substrate became more hydrophilic with the test fluid.

[0043] (Salt resistance test evaluation-1) A stirring bar was placed in a 200 ml styrene bottle, wettability control agents to be described below (aqueous silica sols of Synthesis Examples 1 to 6, and aqueous silica sols (ST-0 and ST-OXS)), pure water and brine with a salt concentration of 4.5% by mass were then added while stirring with a magnetic stirrer to prepare 150 g of a mixed solution with a salt concentration of 4.0% by mass (a sodium chloride concentration of 2.4% by mass, a magnesium chloride concentration of 1% by mass, a calcium chloride concentration of 0.1% by mass, and a concentration of other salt components of 0.5% by mass) and a silica (solid content) concentration of 0.5% by mass, and the mixture was stirred for 1 hour. This was used as a brine test sample for evaluating the salt resistance of the chemical liquid in brine. The DLS average particle diameter of the aqueous silica sol (silica particles) in the obtained brine test sample was evaluated. The brine test sample was left at room temperature (25°C) for a predetermined time (refer to Table 1 and Table 2), and the appearance of the brine test sample and the DLS average particle diameter of the aqueous silica sol (silica particles) in the sample were evaluated. In addition, for the salt resistance, the sample was held at room temperature for a predetermined time (10 hours), the salt resistance was then determined (refer to the following <Determination of salt resistance>) based on the measurement results of the DLS average particle diameter of the aqueous silica sol (silica particles) in the sample and the appearance was evaluated. The results obtained above are shown in Table 1. <Determination of salt resistance> A: the ratio of the DLS average particle diameter after the salt resistance test to the DLS average particle diameter before the test was less than 1.5. B: the ratio of the DLS average particle diameter after the salt resistance test to the DLS average particle diameter before the test was 1.5 or more and less than 2.0. C: the ratio of the DLS average particle diameter after the salt resistance test to the DLS average particle diameter before the test was 2.0 or more, or the DLS average particle diameter could not be measured because the silica sol was gelled and a white precipitate was formed. The salt resistance test results indicate that A was the most preferable result, followed by B and C.

[0044] (Synthesis Example 1: Preparation of wettability control agents used in Example 1, Example 4, Example 5 and Example 10) After 1,200 g of the aqueous silica sol (Snowtex (product name) ST-O, commercially available from Nissan Chemical Corporation, silica concentration = 20.5% by mass, an average particle diameter of 11.0 nm, determined by the BET method, and an average particle diameter of 17.2 nm, determined by the DLS method) and a magnetic stirring bar were placed in a 2,000 mL glass eggplant flask, while stirring with a magnetic stirrer, 191.0 g of 3-glycidoxypropyltrimethoxysilane (product name Dynasylan GLYMO, commercially available from Evonik Industries) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.78. Next, a cooling pipe through which tap water flowed was installed at the top of the eggplant flask, and while refluxing, the aqueous sol was heated to 60°C and held at 60°C for 4 hours and then cooled. After cooling to room temperature, the aqueous sol was removed. 1,391.0 g of an aqueous silica sol (dispersion) of Synthesis Example 1 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica in the aqueous silica sol = 0.78, silica solid content = 21.2% by mass, pH = 2.8, electrical conductivity = 353 pS / cm, DLS average particle diameter = 23.2 nm, D90 = 21.5 nm, and the amount of silane bonds of 1.5 molecules / nm2). The aqueous silica sol of Synthesis Example 1 was used as wettability control agents in Example 1, Example 4, Example 5 and Example 10 in the following test.

[0045] (Synthesis Example 2: Preparation of wettability control agent used in Example 2 and Example 6) After 400 g of an aqueous silica sol (Snowtex (product name) ST-O, commercially available from Nissan Chemical Corporation, silica solid content concentration = 20.5% by mass, an average particle diameter of 11.0 nm, determined by the BET method, and an DLS average particle diameter of 17.2 nm) and a magnetic stirring bar were placed in a 1 L glass eggplant flask, and while stirring with a magnetic stirrer, 91.0 g of lactic acid was added and the mixture was stirred at room temperature for 30 minutes. Then, while stirring, 52.1 g of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (KBM-602, commercially available from Shin-Etsu Chemical Co., Ltd.) was added so that the mass ratio of the silane compound to the silica (colloidal silica) in the aqueous silica sol was 26 0.64. Next, a cooling pipe through which tap water flowed was installed at the top of the eggplant flask, and while refluxing, the aqueous sol was heated to 60°C and held at 60°C for 4 hours and then cooled. After cooling to room temperature, the aqueous sol was removed. 543.1 g of an aqueous silica sol (dispersion) of Synthesis Example 2 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica solid content in the aqueous silica sol = 0.64, silica solid content = 17.5% by mass, pH = 3.6, electrical conductivity = 9,030 pS / cm, DLS average particle diameter = 21.1 nm, D90 = 26.7 nm, and the amount of silane bonds = 0.7 molecules / nm2). The aqueous silica sol of Synthesis Example 2 was used as wettability control agents in Example 2 and Example 6 in the following test.

[0046] (Synthesis Example 3: Preparation of wettability control agent used in Example 3) After 1,200 g of an aqueous silica sol (Snowtex (product name) ST-OXS, commercially available from Nissan Chemical Corporation, silica concentration = 10.5% by mass, an average particle diameter of 5.0 nm, determined by the BET method, and an average particle diameter of 8.5 nm, determined by the DLS method) and a magnetic stirring bar were placed in a 2,000 mL glass eggplant flask, and while stirring with a magnetic stirrer, 209.1 g of 3-glycidoxypropyltrimethoxysilane (product name Dynasylan GLYMO, commercially available from Evonik Industries) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.78. Next, a cooling pipe through which tap water flowed was installed at the top of the eggplant flask, and while refluxing, the aqueous sol was heated to 60°C and held at 60°C for 4 hours and then cooled. After cooling to room temperature, the aqueous sol was removed. 1,409.1 g of an aqueous silica sol (dispersion) of Synthesis Example 3 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica in the aqueous silica sol = 0.78, silica solid content = 8.9% by mass, pH = 2.9, electrical conductivity = 272 pS / cm, DLS average particle diameter = 12.7 nm, D90 = 21 nm, and the amount of silane bonds of 2.0 molecules / nm2). The aqueous silica sol of Synthesis Example 3 was used as a wettability control agent in Example 3 in the following test.

[0047] (Synthesis Example 4: Preparation of wettability control agent used in Example 7) After 1,200 g of an aqueous silica sol (Snowtex (product name) ST-OL, commercially available from Nissan Chemical Corporation, silica concentration = 20.5% by mass, an average particle diameter of 45.0 nm, determined by the BET method, and an average particle diameter of 80.5 nm, determined by the DLS method) and a magnetic stirring bar were placed in a 2,000 mL glass eggplant flask, and while stirring with a magnetic stirrer, 46.7 g of 3-glycidoxypropyltrimethoxysilane (product name Dynasylan GLYMO, commercially available from Evonik Industries) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.19. Next, a cooling pipe through which tap water flowed was installed at the top of the eggplant flask, and while refluxing, the aqueous sol was heated to 60°C and held at 60°C for 4 hours and then cooled. After cooling to room temperature, the aqueous sol was removed. 1,246.7 g of an aqueous silica sol (dispersion) of Synthesis Example 4 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica in the aqueous silica sol = 0.19, silica solid content = 22.5% by mass, pH = 3.2, electrical conductivity = 310 pS / cm, DLS average particle diameter = 79.8 nm, and D90 = 85.8 nm). The aqueous silica sol of Synthesis Example 4 was used as a wettability control agent in Example 7 in the following test.

[0048] (Synthesis Example 5: Preparation of wettability control agent used in Example 8) After 1,200 g of an aqueous silica sol (Snowtex (product name) ST-O, commercially available from Nissan Chemical Corporation, silica concentration = 20.5% by mass, an average particle diameter of 11.0 nm, determined by the BET method, and an average particle diameter of 17.2 nm, determined by the DLS method) and a magnetic stirring bar 28 were placed in a 2,000 mL glass eggplant flask, and while stirring with a magnetic stirrer, 211.9 g of [3-(trimethoxysilyl)propyl]succinic anhydride (X-12-967C, commercially available from Shin-Etsu Chemical Co., Ltd.) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.86. Next, a cooling pipe through which tap water flowed was installed at the top of the eggplant flask, and while refluxing, the aqueous sol was heated to 60°C and held at 60°C for 4 hours and then cooled. After cooling to room temperature, the aqueous sol was removed. 1,411.9 g of an aqueous silica sol (dispersion) of Synthesis Example 1 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica in the aqueous silica sol = 0.86, silica solid content = 20.7% by mass, pH = 2.1, electrical conductivity = 908 pS / cm, DLS average particle diameter = 19.0 nm, and D90 = 18.0 nm). The aqueous silica sol of Synthesis Example 5 was used as a wettability control agent in Example 8 in the following test.

[0049] (Synthesis Example 6: Preparation of wettability control agent used in Example 9) 1,247.8 g of an aqueous silica sol (dispersion) of Synthesis Example 6 subjected to a surface treatment with a silane compound was obtained (the mass ratio of the silane compound to the silica in the aqueous silica sol = 0.20, silica solid content = 21.1% by mass, pH = 2.9, electrical conductivity = 516 pS / cm, DLS average particle diameter = 19.4 nm, and D90 = 19.0 nm) in the same operation as in Synthesis Example 1 except that 47.8 g of 3-glycidoxypropyltrimethoxysilane (product name Dynasylan GLYMO, commercially available from Evonik Industries) was added so that the mass ratio of the silane compound to the silica (colloidal silica particles) in the aqueous silica sol was 0.20. The aqueous silica sol of Synthesis Example 6 was used as a wettability control agent in Example 9 in the following test.

[0050] (Wettability control agent used in Comparative Example 1) As the wettability control agent used in Comparative Example 1, an aqueous silica sol (Snowtex (product name) ST-O, commercially available from Nissan Chemical Corporation, silica solid content concentration = 20.5% by mass, BET method average particle diameter = 11.0 nm, DLS average particle diameter = 18.6 nm, D90 = 21.0 nm) (aqueous silica sol containing uncoated silica particles) was used in the following test.

[0051] (Wettability control agent used in Comparative Example 2) As the wettability control agent used in Comparative Example 2, an aqueous silica sol (Snowtex (product name) ST-OXS, commercially available from Nissan Chemical Corporation, silica solid content concentration = 10.5% by mass, BET method average particle diameter = 5.0 nm, DLS average particle diameter = 8.6 nm, and D90 = 19.1 nm) (aqueous silica sol containing uncoated silica particles) was used in the following test.

[0052] (Preparation Example 1) A stirring bar was placed in a 120 mL styrene bottle, and 2.4 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 1) used in Examples 1, 4 and 5 was added. While stirring with a magnetic stirrer, 8.8 g of pure water was added, and 88.8 g of brine with a salt concentration of 4.5% by mass was added to prepare a test fluid 1 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass (a sodium chloride concentration of 2.4% by mass, a magnesium chloride concentration of 1% by mass, a calcium chloride concentration of 0.1% by mass, a concentration of other salt components of 0.5% by mass, the same applies hereinafter).

[0053] (Preparation Example 2) A stirring bar was placed in a 120 mL styrene bottle, and 2.9 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 2) used in Examples 2 and 6 was added. While stirring with a magnetic stirrer, 8.3 g of pure water was added, 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 2 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0054] (Preparation Example 3) A stirring bar was placed in a 120 mL styrene bottle, and 5.6 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 3) used in Example 3 was added. While stirring with a magnetic stirrer, 5.6g of pure water was added, and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 3 30 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0055] (Preparation Example 4) A stirring bar was placed in a 120 mL styrene bottle, and 2.2 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 4) used in Example 7 was added. While stirring with a magnetic stirrer, 8.9 g of pure water was added, and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 4 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0056] (Preparation Example 5) A stirring bar was placed in a 120 mL styrene bottle, and 2.4 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 5) used in Example 8 was added. While stirring with a magnetic stirrer, 8.7 g of pure water was added and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 5 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0057] (Preparation Example 6) A stirring bar was placed in a 120 mL styrene bottle, and 2.4 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 6) used in Example 9 was added. While stirring with a magnetic stirrer, 8.7 g of pure water was added and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 6 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0058] (Preparation Example 7) A stirring bar was placed in a 120 mL styrene bottle, and 47.2 g of the wettability control agent (aqueous silica sol produced in Synthesis Example 1) used in Example 10 was added. While stirring with a magnetic stirrer, 52.8 g of brine with a salt concentration of 4.5% by mass was added to prepare a test fluid 7 with a silica solid content concentration of 10% by mass and a salt concentration of 2.4% by mass.

[0059] (Preparation Example 8) A stirring bar was placed in a 120 mL styrene bottle, and 2.4 g of an uncoated aqueous silica sol (Snowtex (registered trademark) ST-O, commercially available from Nissan Chemical Corporation, silica solid content concentration = 20.5% by mass, an average particle diameter of 11.0 nm, determined by the BET method, and a DLS average particle diameter of 17.2 nm) was added as the wettability control agent used in Comparative Example 1. While stirring with a magnetic stirrer, 8.8 g of pure water was added and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 8 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0060] (Preparation Example 9) A stirring bar was placed in a 120 mL styrene bottle, and 4.8 g of Snowtex (registered trademark, ST-OXS, commercially available from Nissan Chemical Corporation) was added as the wettability control agent used in Comparative Example 2. While stirring with a magnetic stirrer, 6.4 g of pure water was added and 88.8 g of brine with a salt concentration of 4.5% by mass was then added to prepare a test fluid 9 with a silica solid content concentration of 0.5% by mass and a salt concentration of 4% by mass.

[0061] The amount of adsorption and the wettability were evaluated for each of the test fluids 1 to 9 according to (evaluation-1 regarding amount of adsorption onto substrate) and (evaluation (1 to 3) regarding change in wettability of substrate). In addition, the salt resistance was evaluated according to (salt resistance test evaluation-1) for the wettability control agents (aqueous silica sols of Synthesis Examples 1 to 6, and aqueous silica sols (ST-0 and ST-OXS)) used in Examples 1 to 10, Comparative Example 1 and Comparative Example 2. The obtained results are shown in Table 1 and Table 2. In addition, FIG. 5 shows the shapes of crude oil droplets used for measuring the contact angle (a) obtained with the test fluids (test fluids 1 to 3, 8, and 4 to 7) of Examples 1 to 3, Comparative Example 1 and Examples 7 to 10 in (evaluation-1 regarding change in wettability of substrate) and the shape of a blank (contact angle (b)) crude oil droplet, FIG. 6 shows the shape of a crude oil droplet used for measuring the contact angle (a) obtained in the test fluid (test fluid 1) of Example 4 in (evaluation-2 regarding change in wettability of substrate) and the shape of a blank (contact angle (b)) crude oil droplet, and FIG. 7 shows the shapes of crude oil droplets used for measuring the contact angle (a) obtained with the test fluids (test fluids 1 5 and 2) of Example 5 and Example 6 in (evaluation-3 regarding change in wettability of substrate) and the shape of a blank (contact angle (b)) crude oil droplet. In FIG. 5 to FIG. 7, the black circular or semicircular parts indicate crude oil droplets, and the area above the black parts indicates the substrate. In addition, in the blank shown in FIG. 5, the contact angle to be measured is indicated as 0. Here, since slide glass was used as the substrate in 10 (evaluation-3 regarding change in wettability of substrate), the substrate (transparent) part is indicated by a dashed line in FIG. 7.

[0062] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Physical properties of wettability control agent (aqueous silica sol) (Synthesis Example 1) (Synthesis Example 2) (Synthesis Example 3) (Synthesis Example 1) (Synthesis Example 1) (Synthesis Example 2) pH 2.8 3.6 2.9 2.8 2.8 3.6 Electrical conductivity [mS / cml 0.4 9.0 0.3 0.4 0.4 9.0 Viscosity [mPa-sl 6.5 7.3 5.2 6.5 6.5 7.3 DLS average particle diameter |ntn] 23.2 21.1 12.7 23.2 23.2 21.1 D90 [nml 21.5 26.7 21 21.5 21.5 26.7 Amount of silane added [molecules / nm2] 8 8 8 8 8 8 Physical properties of test fluid Test fluid 1 Test fluid 2 Test fluid 3 Test fluid 1 Test fluid 1 Test fluid 2 Salt concentration [% by mass] 4 4 4 4 4 4 Inorganic oxide solid content [% by mass! 0.5 0.5 0.5 0.5 0.5 0.5 DLS average particle diameter [nml 22.8 21.9 22.0 22.8 22.8 21.9 Evaluation regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Fl (AF value at 2,000 seconds) -53.5 -20.7 -84.1 -53.5 -53.5 -20.7 F2 (AF value at 12,000 seconds) -63.6 -30.2 -86.5 -63.6 -63.6 -30.2 F3 (Fl - F2) 10.1 9.5 2.4 10.1 10.1 9.5 Evaluation result of amount of adsorption A A A A A A Evaluation regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-2 regarding change in wettability Evaluation-3 regarding change in wettability Evaluation-3 regarding change in wettability Droplet (crude oil droplet) volume [pL] 0.3 0.3 0.1 0.1 0.1 0.2 Contact angle (a) [°] 26.0 21.7 25.8 85.9 27.2 18.5 Contact angle (b) (blank) Pl 32.5 32.5 32.5 99.8 33.7 33.7 [Contact angle (b) - Contact angle (a)l [°] 6.5 10.8 6.7 13.9 6.5 15.2 Salt resistance test evaluation Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Test conditions 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours DLS average particle diameter [nm] (of salt resistance sample) before salt resistance test 25.3 21.9 22.0 25.3 25.3 21.9 DLS average particle diameter [nm] after salt resistance test 22.1 21.3 Tin 22.1 22.1 21.3 Appearance Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Ratio of DLS average particle diameter after salt resistance test / DLS average particle diameter before test 0.9 1.0 1.3 0.9 0.9 1.0 Evaluation result of salt resistance test A A A A A A

[0063] [Table 2] Example 7 Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Physical properties of wettability control agent (aqueous silica sol) (Synthesis Example 4) (Synthesis Example 5) (Synthesis Example 6) (Synthesis Example 1) (ST-O) (ST-OXS) pH 3.2 2.1 2.9 2.8 2.7 3.1 Electrical conductivity [mS / cml 0.3 0.9 0.5 0.4 0.7 0.4 Viscosity [mPa-sl 5.2 6.1 4.3 6.5 4.9 4.2 DLS average particle diameter [nml 79.8 19.0 19.4 23.2 18.6 8.6 D90 [nml 85.8 18.0 19.0 21.5 21.0 19.1 Amount of silane added [molecules / nm2] 8 8 2 8 0 0 Physical properties of test fluid Test fluid 4 Test fluid 5 Test fluid 6 Test fluid 7 Test fluid 8 Test fluid 9 Salt concentration [% by mass] 4 4 4 2.4 4 4 Inorganic oxide solid content [% by mass] 0.5 0.5 0.5 10 0.5 0.5 DLS average particle diameter [nm] 82.9 30.8 22.4 26.0 29.6 22.1 Evaluation regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Evaluation-1 regarding amount of adsorption Fl (AF value at 2,000 seconds) 112.6 -366.2 -37.6 -80.0 -129.4 -105.2 F2 (AF value at 12,000 seconds) 114.4 -365.0 -39.2 -81.5 -160.9 -149.1 F3 (Fl - F2) 1.8 -1.2 1.6 1.5 31.5 43.9 Evaluation result of amount of adsorption A A A A C C Evaluation regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Evaluation-1 regarding change in wettability Droplet (crude oil droplet) volume [pL] 0.5 0.5 0.5 0.5 0.3 0.1 Contact angle (a) [°] 27.3 21.4 23.7 21.3 22.8 20.2 Contact angle (b) (blank) [°1 32.5 32.5 32.5 32.5 32.5 32.5 [Contact angle (b) - Contact angle (a)] [°] 5.2 11.1 8.8 11.2 9.7 12.3 Salt resistance test evaluation Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Salt resistance test evaluation-1 Test conditions 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours 25°C x 10 hours DLS average particle diameter [nm] (of salt resistance sample) before salt resistance test 82.9 30.8 22.4 26.0 29.6 22.1 DLS average particle diameter after salt resistance test [nm] 83.1 23.7 22.1 26.0 73.3 2533 Appearance Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Colloid-colored transparent liquid Cloudy Cloudy Ratio of DLS average particle diameter after salt resistance test / DLS average particle diameter before test 1.0 0.8 1.0 1.0 2.5 114.6 Evaluation result of salt resistance test A A A A C C

[0064] The aqueous silica sols used as the test fluids that had the satisfactory results in the above evaluations (evaluation-1 regarding amount of adsorption) and (evaluation-1 regarding change in wettability) to (evaluation-3 regarding change in wettability) can be said to be useful as the wettability control agent that can conformally coat the rock surface and make it hydrophilic. In addition, the sample that had the satisfactory result in the above (salt resistance test evaluation-1) can be said to be a sample suitable for injection into the underground bedrock. As shown in Table 1, regarding the test fluids 1 to 3 containing the wettability control agents (aqueous silica sols of Synthesis Examples 1 to 3) used in Example 1 (and Examples 4 and 5), Example 2 (and Example 6) and Example 3, and as shown in Table 2, the test fluids 4 to 7 containing the wettability control agent (aqueous silica sols of Synthesis Examples 4 to 6, and 1) used in Example 7 to Example 10, in the evaluation regarding the amount of adsorption, it was confirmed that the AF value (F3) from 2,000 seconds to 12,000 seconds after the start of resonance was in a range of 20 to 20, that is, the amount of adsorption was nearly saturated. In addition, in all of (evaluation-1 regarding change in wettability: Berea sandstone), (evaluation-2 regarding change in wettability: calcite), and (evaluation-3 regarding change in wettability: slide glass) using these test fluids 1 to 3, and (evaluation-1 regarding change in wettability: Berea sandstone) using the test fluids 4 to 7, the contact angle (a) was smaller than the contact angle (b) of the blank, the values of [contact angle (b) - contact angle (a)] were 5.2 to 15.2°, all of which were 3° or more, and the test fluid 1 to test fluid 7 changed the wettability of these substrates to be more hydrophilic. Here, in (evaluation-1 regarding change in wettability: Berea sandstone) and (evaluation-3 regarding change in wettability: slide glass), it was confirmed that the contact angle (a) was 30° or less, and the substrate surface had strong wettability. In addition, it was confirmed that the wettability control agent (aqueous silica sols of Synthesis Examples 1 to 6) used in the test fluid was a sample having excellent salt resistance. That is, it was suggested that the wettability control agent used in the examples was a wettability control agent that could conformally coat the rock surface and make it hydrophilic and could also be injected into the underground bedrock, and the results showed that, when the agent was injected into the underground bedrock, effects such as securing a flow path for a hydrophilic chemical liquid without causing a risk of formation blockage could be expected. In Comparative Example 1 and Comparative Example 2, in (evaluation-1 regarding 5 change in wettability), the value of [contact angle (b) - contact angle (a)] was 3° or more, that is, an effect of improving the wettability of rock surfaces could be expected. However, in both (evaluation-1 regarding adsorption onto substrate) and (salt resistance test evaluation-1), the evaluation was C, which was not a good result, that is, when the agent was injected into the underground bedrock, there was a risk of formation blockage, and there was a risk 10 of aggregation occurring due to mixing with brine during injection. Description of the Reference Numerals

[0065] 1 Three-phase contact angle measurement device 2 External cell 15 3 Substrate 4 Capillary needle 5 Surrounding liquid d Crude oil droplet

Claims

1. A wettability control agent for rock surfaces, which makes rock surfaces hydrophilic through conformal coating, comprisingsilica particles (a) having a DLS average particle diameter of 5 to 200 nm, which is determined by a dynamic light scattering method, and an aqueous medium (b),wherein at least some of the silica particles are coated with a silane compound (c) having a hydrophilic organic group.

2. The wettability control agent for rock surfaces according to claim 1,wherein the hydrophilic organic group is an epoxy group-containing organic group, an amino group-containing organic group, a hydroxy group-containing organic group, or a carboxy group-containing organic group.

3. The wettability control agent for rock surfaces according to claim 1 or 2, wherein, in a test method in which a sensor in which an electrode layer and a quartz layer are laminated on a crystal resonator is made to resonate in a medium containing brine containing calcium ions and magnesium ions and the wettability control agent for rock surfaces,a value (F3) obtained by subtracting a AF value (F2) indicating a change in weight of an accumulation layer containing a silica component accumulated on a surface of the sensor from the start of resonance to 12,000 seconds from a AF value (Fl) indicating a change in weight of the accumulation layer containing the silica component accumulated on the surface of the sensor from the start of resonance to 2,000 seconds is -20 to 20 when resonance frequency of the crystal resonator is 25 MHz.

4. The wettability control agent for rock surfaces according to any one of claims 1 to 3,wherein, in evaluation of wettability of rock surfaces in which a crude oil with avolume of 0.01 to 1 pl is brought into contact with a bottom of a rock slab in brine containing the wettability control agent for rock surfaces, a contact angle between an outer surface of a droplet of the crude oil and the rock slab is reduced by 3° or more compared to the contact angle evaluated in brine not containing the wettability control agent.

5. The wettability control agent for rock surfaces according to claim 3 or 4, wherein the brine is brine containing sodium ions and having a salt concentration of0.1 to 30% by mass.

6. The wettability control agent for rock surfaces according to claim 3, wherein the resonance frequency of the crystal resonator is in a range of 1 MHz to100 MHz.

7. The wettability control agent for rock surfaces according to claim 1, wherein the wettability control agent is a wettability control agent for storing a fluid in bedrocks or securing a flow path in bedrocks.

8. The wettability control agent for rock surfaces according to claim 7, wherein the fluid is a gas or liquid containing carbon dioxide, a water-based fluid, ora water-based fluid containing fine rock particles with a size of 10 pm or less.

9. A method for controlling wettability of rock surfaces, comprisingcontrolling the wettability control agent for rock surfaces according to any one of claims 1 to 8 such that a silica particle concentration is 0.1 to 30% by mass in an aqueous medium, and applying the wettability control agent to rock surfaces.

10. A method for evaluating wettability of rock surfaces, comprisingbringing a crude oil with a volume of 0.01 to 1 pl into contact with a bottom of a rock slab in brine containing the wettability control agent for rock surfaces according to any oneof claims 1 to 3, and evaluating a contact angle between an outer surface of a droplet of the crude oil and the rock slab.INTERNATIONAL SEARCH REPORT International application No. PCT / JP2024 / 003I48 A. CLASSIFICATION OF SUBJECT MATTER C09K&3S(2006.01)i; C01B 33 / / 46(2006.01 )i: CY / 9 / < 3 / 66(2006.01 )i: C09K«W(2006.01)i; GOIN13 / 02(2006.01)1 FI: C09K8 / 58; C01B33 / 146; G01N13 / 02; C09K3 / 00 R: C09K8 / 60 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) C09K8 / 58: C01B33 / 146; C09K3 / 00; C09K8 / 60: G01N13 / 02 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Published examined utility model applications of Japan 1922-1996 Published unexamined utility model applications of Japan 1971-2024 Registered utility model specifications of Japan 1996-2024 Published registered utility model applications of Japan 1994-2024 Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. X X KR 10-1872020 Bl (KOREA INSTITUTE OF GEOSCIENCE AND MINERAL RESOURCES(KIGAM)) 27 June 2018 (2018-06-27) claims, examples, drawings CN 109456745 A (CHINA PETROLEUM &CHEMICAL CORPORATION) 12 March 2019 (2019-03-12) claims, examples, paragraphs [0030J-[0032] 1-10 1-10 X CN 102838981 A (SHAANXI RESEARCH DESIGN INSTITUTE OF PETROLEUM CHEMICAL INDUSTRY) 26 December 2012 (2012-12-26) claims, examples, paragraphs [0012]-[0017] 1-10 | | Further documents are listed in the continuation of Box C. | / | See patent family annex. * Special categories of cited documents: “T” later document published after the international filing date or priority “A” document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand the to be of particular relevance principle or theory underlying the invention “D” document cited by the applicant in die international application “X” document of particular relevance; the claimed invention cannot be “E" earlier application orpatent but published on or after the international considered novel or cannot be considered to involve an inventive step filing date when the document is taken alone •SL” document which may throw doubts on priority claim(s) or which is “Y” document of particular relevance; the claimed invention cannot be cited to establish the publication date of another citation or other considered to involve an inventive step when the document is special reason (as specified) combined with one or more other such documents, such combination “O” document referring to an oral disclosure, use, exhibition or other being obvious to a person skilled in the art means document member of the same patent family “P” document published prior to the international filing date but later than the priority date claimed Date of the actual completion of the international search 16 April 2024 Date of mailing of the international search report 07 May 2024 Name and mailing address of the ISA / JP Japan Patent Office (ISA / JP) 3-4-3 Kasumigaseki, Chiyoda-ku, Tokyo 100-8915 Japan Authorized officer Telephone No.Form PCT / ISA / 210 (second sheet) (July 2022)INTERNATIONAL SEARCH REPORT Information on patent family membersInternational application No.PCT / JP2024 / 003I48Patent document cited in search report Publication date (day / month / year) Patent family member)s) Publication date (day / month / year) KR 10-1872020 Bl 27 June 2018 (Family: none) CN 109456745 A 12 March 2019 (Family: none) CN 102838981 A 26 December 2012 (Family: none)

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