HIGHLY INHIBITED DRILLING Russian patent published in 2007 - IPC C09K8/20 

FIELD: oil and gas production.

SUBSTANCE: invention relates to drilling oil and gas wells, in particular in presence of massive deposits of high-viscosity clays liable to swell, including cases when integrity of wellbore is changed, especially in inclined section. Drilling fluid of invention is composed of. wt %: bentonite clay 4.0-10.0, polyanione cellulose 1.0-2.0, potassium chloride 1.0-5.0, ferrochrome-lignosulfonate 1.0-3.0, phosphatide concentrate (oil containing additive) 0.5-1.0, barite 0.5-10.0, potassium methyl silicate 0.5-1.5, potassium acetate 0.5-1.5, soda ash 0.1-0.5, bischofite 2.0-5.0, nitrilotrimethylphosphonic acid 0.02-0.03, foam suppressor 0.5-1.0, graphite 0.5-1.0, and water - the rest.

EFFECT: improved strengthening, lubricating, and anti-stick properties of drilling fluid and simultaneously improved coefficient of restoring original permeability through increasing inhibitory and waterproofing ability of fluid filtrate.

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