Abstract: To provide an additive for crude oil recovery, used in secondary/tertiary recovery of crude oil, which has high heat resistance and high mechanical shear resistance, of which the viscous property does not degrade even under high-temperature and high-shear conditions; has high pseudoplastic flowability and therefore has a light transfer workload; and is a naturally-derived one and is therefore highly biodegradable and has least adverse impact on environment. An additive for crude oil recovery, which contains cellulose fibers having a number-average fiber diameter of from 2 to 500 nm and a fiber aspect ratio of 50 or more and having a cellulose I-type crystal structure, and, in the cellulose fibers, a hydroxyl group on a surface of the cellulose fibers is preferably chemically modified.

Abstract: To provide an additive for drilling mud, used in drilling for petroleum, natural gas, civil engineering, mines, etc., which has high heat resistance and high mechanical shear resistance, of which the viscous property does not degrade even under high-temperature and high-shear conditions; has high pseudoplastic flowability and therefore secures high flowability during discharging; and is a naturally-derived one and is therefore highly biodegradable and has least adverse impact on environment. An additive for drilling mud, which contains cellulose fibers having a number-average fiber diameter of from 2 to 500 nm and a fiber aspect ratio of 50 or more and having a cellulose I-type crystal structure.

Abstract: A cellulose fiber nano-dispersion pressing-in device for pressing a liquid, in which a cellulose fiber of a conifer-derived pulp is nano-dispersed, into a stratum, includes a grinding means for grinding the conifer-derived pulp in water, a dilution means for diluting a cellulose fiber-containing liquid obtained in the grinding means and a pressing-in means for pressing a nano-dispersion of the cellulose fiber obtained in the dilution means into a well. Therefore, it is applicable to water-stopping operation in a civil engineering process or to a process of industrial production of hydrocarbons such as crude oil, gas and the like for improving the recovery rate thereof.

Abstract: To provide an additive for crude oil recovery, used in secondary/tertiary recovery of crude oil, which has high heat resistance and high mechanical shear resistance, of which the viscous property does not degrade even under high-temperature and high-shear conditions; has high pseudoplastic flowability and therefore has a light transfer workload; and is a naturally-derived one and is therefore highly biodegradable and has least adverse impact on environment. An additive for crude oil recovery, which contains cellulose fibers having a number-average fiber diameter of from 2 to 500 nm and a fiber aspect ratio of 50 or more and having a cellulose I-type crystal structure, and, in the cellulose fibers, a hydroxyl group on a surface of the cellulose fibers is preferably chemically modified.

Abstract: To provide an additive for drilling mud, used in drilling for petroleum, natural gas, civil engineering, mines, etc., which has high heat resistance and high mechanical shear resistance, of which the viscous property does not degrade even under high-temperature and high-shear conditions; has high pseudoplastic flowability and therefore secures high flowability during discharging; and is a naturally-derived one and is therefore highly biodegradable and has least adverse impact on environment. An additive for drilling mud, which contains cellulose fibers having a number-average fiber diameter of from 2 to 500 nm and a fiber aspect ratio of 50 or more and having a cellulose I-type crystal structure.

Abstract: This invention relates to a method of producing particulate polymers. This production method is characterized in that a mixture of an isocyanate compound containing two or more isocyanato groups per molecule and a surfactant containing two or more hydroxyl groups per molecule is emulsified and allowed to cure in a dispersing medium which does not dissolve the isocyanate compound without use of a protective colloid. According to the production method of the invention, there occurs no aggregation of polymer particles during and after the curing reaction.