METHOD OF PREPARING CEMENT SLURRY (VERSIONS) Russian patent published in 2010 - IPC C09K8/467 C04B40/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of preparing cement slurry and can be used in oil and gas industry and particularly in extraction of hydrocarbons from porous media. The method of preparing cement slurry involves mixing portland cement and water, adding an additive and treating the obtained mortar using a device placed inside a cement pipe with high-gradient magnetic field whose intensity varies from 0.6 to 1.0 kOe and direction reverses with period of 6-12 cm in the direction of movement of the mortar and which provides intensity gradient of 3-5 kOe/cm. The additive used is in form of nanostructures in amount of 0.1-3% of the weight of the mortar and the additive is added before magnetic treatment. In another version of the method of preparing cement slurry which involves mixing portland cement and water, addition of an additive and treatment of the obtained mortar in a cement pipe using a device with high-gradient magnetic field which varies its intensity and direction opposite the direction of movement of the mortar, the device is placed outside the cement pipe and the said magnetic field varies its intensity between 0.6 and 2.0 kOe and reverses its direction with period of 3-20 cm and provides intensity gradient of 3-8 kOe/cm. The additive used is in form of nanostructures in amount of 0.1-3% of the weight of the mortar and the additive is added before magnetic treatment. The invention is developed in subclaims of the formula of invention.

EFFECT: higher quality of cement slurry due to improvement of reinforcement and crystallising properties of nanoadditives with provision for their uniform distribution in the cement slurry.

16 cl, 2 ex, 4 tbl