BIOPOLYMER DRILLING FLUID Russian patent published in 2006 - IPC C09K8/10 

FIELD: oil and gas production.

SUBSTANCE: invention relates to polymer drilling fluids used in boring of gas and oil wells, in particular to clay-free biopolymer drilling fluid, which are used when performing boring under complicated mining and geological conditions, including those in chemogenous deposits and at high borehole temperatures and also in cases of directional wells and horizontal well sites. Biopolymer drilling fluid of invention contains, wt %: polymeric filtration reducer: polyanionic cellulose or carboxymethylcellulose, or oxyethylcellulose, or hydrolyzed polyacrylonitrile, 0.1-1.0; xanthane-type biopolymer, 0.2-0.5; fatty acid ethylenediamides: condensation product of ethylenediamine and phosphatide concentrate, 0.05-3.0; alkali metal humates: coal-alkali reagent or humate-potassium reagent, 3,0-6.0; alkali and/or alkali metal salts: KC, NaCl, CaCl₂, MgCl₂; bischofite, 3.0-40.0; and water in balancing amounts.

EFFECT: reduced amount and concentration of components required to prepare drilling fluid at the same inhibitory, lubricating, filtration, and antiadhering properties, improved structural-rheological properties, heat and salt resistance, and reduced harmful environmental effects.

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