Abstract: A dispersion includes silane-bonded inorganic oxide particles having surfaces modified with a hydrolyzable silane, and a liquid dispersion medium which contains a hydrolysate of the hydrolyzable silane; the ratio of (the number of moles of silicon atoms of the hydrolysate of the hydrolyzable silane in the dispersion medium)/(the number of moles of silicon atoms of the silane bonded to the surfaces of the particles) is 0.2 to 30; and Q4 is greater than that before the surface modification with silane, wherein Q4 corresponds to the case where the number of bridging oxygen atoms between silicon atoms of the silica particles is 4/2 per one silicon atom as determined by Si-NMR observation. The inorganic oxide particles have an average diameter of 5 nm to 100 nm and are particles of silica and at least one inorganic oxide from the group of alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide.

Abstract: A dispersion includes silane-bonded inorganic oxide particles having surfaces modified with a hydrolyzable silane, and a liquid dispersion medium which contains a hydrolysate of the hydrolyzable silane; the ratio of (the number of moles of silicon atoms of the hydrolysate of the hydrolyzable silane in the dispersion medium)/(the number of moles of silicon atoms of the silane bonded to the surfaces of the particles) is 0.2 to 30; and Q4 is greater than that before the surface modification with silane, wherein Q4 corresponds to the case where the number of bridging oxygen atoms between silicon atoms of the silica particles is 4/2 per one silicon atom as determined by Si-NMR observation. The inorganic oxide particles have an average diameter of 5 nm to 100 nm and are particles of silica and at least one inorganic oxide from the group of alumina, tin oxide, zirconium oxide, titanium oxide, and antimony oxide.

Abstract: A dispersion wherein dispersoid particles including colloidal silica and zinc cyanurate are dispersed in a liquid medium. The colloidal silica particles may have an average diameter of 5 to 500 nm, and the dispersion may contain 0.1 to 40% by mass of the particles in terms of SiO2 concentration. Primary particles of the zinc cyanurate may have a major axis length of 50 to 1000 nm, a minor axis length of 10 to 300 nm, and a ratio of major to minor axis length of 2 to 25, and the dispersion may contain 0.1 to 50% by mass of the particles in terms of solids content. A mass ratio of the colloidal silica to the zinc cyanurate particles may be 1:0.01 to 100, and total solids content may be 0.1 to 50% by mass. The liquid medium may be water or an organic solvent.

Abstract: A borehole cement slurry additive that is capable of suppressing the generation of free water from cement slurries in any environment, whether cold regions, mild regions, or hot regions; and a method for storing the same. The borehole cement slurry additive contains: an aqueous dispersion of silica having an average particle size of 3-200 nm as determined via dynamic light scattering; and a compound having an alcoholic hydroxyl group as a dispersion stabilizer, the compound being included in an amount of 1-30 mol per 1,000 g dispersion medium in the aqueous silica dispersion.

Abstract: A chemical fluid for underground injection includes an inorganic substance, an antioxidant (e.g. ascorbic acid, gluconic acid, or a salt thereof, or ?-acetyl-?-butyrolactone, or bisulfite, or disulfite), and water. The inorganic substance may be a colloidal particle or a powder. The inorganic substance may be present in the chemical fluid in amounts of 0.001% by mass to 50% by mass based on the total mass of the chemical fluid for underground injection. The antioxidant may be present in the chemical fluid at a ratio of 0.0001 to 2 of the mass of the antioxidant to the mass of the inorganic substance. A surface of the inorganic substance may be coated with a silane compound. The chemical fluid may further include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or a mixture thereof.

Abstract: A method for producing a silica sol containing a small amount of metal impurities and in which colloidal silica having an elongated particle shape dispersed in a solvent, includes: preparing a raw material liquid by adding a compound as an anion source selected from inorganic acids, organic acids, and their ammonium salts, and ammonia to a colloidal aqueous solution of activated silica having an SiO2 concentration of 1 to 6% by mass and a pH of 2 to 5 so that the mass ratio of the compound to SiO2 is 3.0 to 7.0%; and heating the raw material liquid at 80 to 200° C. for 0.5 to 20 hours. The elongated colloidal silica particles exhibit a DL/DB ratio of 2.5 or more. DL is an average particle diameter as measured by the dynamic light scattering method. DB is a primary particle diameter as measured by the nitrogen gas adsorption method.

Abstract: A method for producing a silica sol containing a small amount of metal impurities and wherein colloidal silica having an elongated particle shape is dispersed in a solvent, by addition of a compound as an anion source and ammonia as an alkali source and heating of the resultant mixture at a predetermined temperature, includes the following steps: (a) preparing a raw material liquid by adding at least one compound as an anion source selected from the group of inorganic acids, organic acids, and ammonium salts of these acids, and ammonia to a silica sol as a raw material having SiO2 of 1% by mass to 30% by mass and a pH of 2 to 5 so the mass ratio of the compound to SiO2 is 0.5% to 1.9%; and (b) heating the raw material liquid prepared in step (a) at 80° C. to 200° C. for 0.5 hours to 20 hours.

Abstract: An additive capable of suppressing generation of free water from a cement slurry even under a high temperature environment of 150° C. or more and a silica-based additive that suppresses, in a cement slurry for cementing in oil fields and gas oil fields, free water under high temperature and high pressure environments of 100° C. or more, the silica-based additive containing an aqueous silica sol containing nanosilica particles with a true density of 2.15 g/cm3 or more and less than 2.30 g/cm3, and a cement slurry for cementing that contains the silica-based additive.

Abstract: An additive for a cement slurry for a well that is capable of suppressing the generation of free water and preventing flotation/separation of low-specific-gravity aggregate while securing sufficient cement strength even at a high temperature and a method for producing this additive are disclosed. The additive contains an aqueous dispersion of silica and a layered silicate.

Abstract: A chemical fluid for underground injection includes an inorganic substance, an antioxidant (e.g. ascorbic acid, gluconic acid, or a salt thereof, or bisulfite, or disulfite), and water. The inorganic substance may be a colloidal particle or a powder. The inorganic substance may be present in the chemical fluid in amounts of 0.001% by mass to 50% by mass based on the total mass of the chemical fluid for underground injection. The antioxidant may be present in the chemical fluid at a ratio of 0.0001 to 2 of the mass of the antioxidant to the mass of the inorganic substance. A surface of the inorganic substance may be coated with a silane compound. The chemical fluid may further include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, or a mixture thereof.

Abstract: Provided is an additive for a cement slurry for a well that is capable of suppressing the generation of free water and preventing flotation/separation of low-specific-gravity aggregate while securing sufficient cement strength even at a high temperature. Also provided is a method for producing this additive. This additive for a cement slurry for a well contains an aqueous dispersion of silica and a layered silicate.

Abstract: Provided are: a borehole cement slurry additive that is capable of suppressing the generation of free water from cement slurries in any environment, whether cold regions, mild regions, or hot regions; and a method for storing the same. The borehole cement slurry additive contains: an aqueous dispersion of silica having an average particle size of 3-200 nm as determined via dynamic light scattering; and a compound having an alcoholic hydroxyl group as a dispersion stabilizer, the compound being included in an amount of 1-30 mol per 1,000 g dispersion medium in the aqueous silica dispersion.

Abstract: An additive capable of suppressing generation of free water from a cement slurry even under a high temperature environment of 150° C. or more and a silica-based additive that suppresses, in a cement slurry for cementing in oil fields and gas oil fields, free water under high temperature and high pressure environments of 100° C. or more, the silica-based additive containing an aqueous silica sol containing nanosilica particles with a true density of 2.15 g/cm3 or more and less than 2.30 g/cm3, and a cement slurry for cementing that contains the silica-based additive.

Abstract: A dispersion wherein dispersoid particles including colloidal silica and zinc cyanurate are dispersed in a liquid medium. The colloidal silica particles may have an average diameter of 5 to 500 nm, and the dispersion may contain 0.1 to 40% by mass of the particles in terms of SiO2 concentration. Primary particles of the zinc cyanurate may have a major axis length of 50 to 1000 nm, a minor axis length of 10 to 300 nm, and a ratio of major to minor axis length of 2 to 25, and the dispersion may contain 0.1 to 50% by mass of the particles in terms of solids content. A mass ratio of the colloidal silica to the zinc cyanurate particles may be 1:0.01 to 100, and total solids content may be 0.1 to 50% by mass. The liquid medium may be water or an organic solvent.

Abstract: A method for producing a silica sol containing a small amount of metal impurities and in which colloidal silica having an elongated particle shape dispersed in a solvent, includes: preparing a raw material liquid by adding a compound as an anion source selected from inorganic acids, organic acids, and their ammonium salts, and ammonia to a colloidal aqueous solution of activated silica having an SiO2 concentration of 1 to 6% by mass and a pH of 2 to 5 so that the mass ratio of the compound to SiO2 is 3.0 to 7.0%; and heating the raw material liquid at 80 to 200° C. for 0.5 to 20 hours. The elongated colloidal silica particles exhibit a DL/DB ratio of 2.5 or more. DL is an average particle diameter as measured by the dynamic light scattering method. DB is a primary particle diameter as measured by the nitrogen gas adsorption method.

Abstract: A method for producing a silica sol containing a small amount of metal impurities and wherein colloidal silica having an elongated particle shape is dispersed in a solvent, by addition of a compound as an anion source and ammonia as an alkali source and heating of the resultant mixture at a predetermined temperature, includes the following steps: (a) preparing a raw material liquid by adding at least one compound as an anion source selected from the group of inorganic acids, organic acids, and ammonium salts of these acids, and ammonia to a silica sol as a raw material having SiO2 of 1% by mass to 30% by mass and a pH of 2 to 5 so the mass ratio of the compound to SiO2 is 0.5% to 1.9%; and (b) heating the raw material liquid prepared in step (a) at 80° C. to 200° C. for 0.5 hours to 20 hours.

Abstract: A crude oil recovery chemical fluid is described and claimed. This fluid has been shown to exhibit excellent resistance to salt and high temperatures. This crude oil recovery chemical fluid includes a silane compound, an aqueous silica sol having an average particle diameter of from about 3 nm to about 200 nm, two or more anionic surfactants, and one or more nonionic surfactants.

Abstract: A crude oil recovery chemical fluid is described and claimed. This fluid has been shown to exhibit excellent resistance to salt and high temperatures. This crude oil recovery chemical fluid includes a silane compound, an aqueous silica sol having an average particle diameter of from about 3 nm to about 200 nm, two or more anionic surfactants, and one or more nonionic surfactants.

Abstract: A crude oil recovery chemical fluid is described and claimed. This fluid has been shown to exhibit excellent resistance to salt and high temperatures. This crude oil recovery chemical fluid includes a silane compound, an aqueous silica sol having an average particle diameter of from about 3 nm to about 200 nm, two or more anionic surfactants, and one or more nonionic surfactants.

Abstract: A crude oil recovery chemical fluid is described and claimed. This fluid has been shown to exhibit excellent resistance to salt and high temperatures. This crude oil recovery chemical fluid includes a silane compound, an aqueous silica sol having an average particle diameter of from about 3 nm to about 200 nm, two or more anionic surfactants, and one or more nonionic surfactants.