DILUTED CATIONIC FRICTION REDUCERS Russian patent published in 2021 - IPC C09K8/68 C09K8/70 E21B43/22 

FIELD: colloidal chemistry.

SUBSTANCE: ‘water-in-oil’ type emulsion and a method for its production are used for the treatment of a subterranean formation. ‘Water-in-oil’ emulsion contains: an oil phase (O) in the form of a continuous phase containing an inert hydrophobic liquid, and an aqueous phase (A) in the form of a dispersed phase of individual particles in an oil phase containing water, a water-soluble polymer and at least one surface-active substance. The oil phase (O) and the aqueous phase (A) are contained in an O/A ratio of about 1 : 8 to about 10 : 1. The water-soluble polymer contains from 40 to 60 wt% of one or more cationic monomers, and from 40 to 60 wt% of one or more non-ionic monomers, the indicated amount being based on the total weight of the water-soluble polymer. The water-soluble polymer is present in an amount from about 5 to about 25 wt% based on the weight of the ‘water-in-oil’ emulsion. An aqueous solution obtained by inverting ‘water-in-oil’ emulsion by adding the specified emulsion to water has an increase in viscosity at least comparable to an increase in the viscosity of an aqueous solution prepared from ‘water-in-oil’ emulsion of the same composition containing 15 wt% more water soluble polymer. A method for treating a section of a subterranean formation includes the following steps: (a) providing ‘water-in-oil’ emulsion of the above composition, (b) inverting the ‘water-in-oil’ emulsion by adding the said emulsion to water in an amount of about 0.1 (about 0, 4 L) to about 5 gallons (about 19 L) of ‘water-in-oil’ emulsion per thousand gallons (about 3785 L) of water to provide a friction reducing treatment solution containing from about 0.0005 wt% to about 0.12 wt% water-soluble polymer based on the weight of the specified solution for treatment; and (c) introducing the treatment solution into a section of the subterranean formation.

EFFECT: achieved technical result is a reduction in the polymer content with an equivalent efficiency of reducing friction compared to emulsions with a higher polymer content, and environmental safety.

15 cl, 2 tbl, 2 ex