PREPARATION METHOD OF COMPOSITION FOR ISOLATION OF LOST-CIRCULATION ZONES IN WELL Russian patent published in 2013 - IPC E21B33/138 C09K8/50 

FIELD: oil and gas industry.

SUBSTANCE: preparation method of a compound for isolation of lost-circulation zones in a well by mixing cement, clay powder, polyacrylamide, water and an additive. First, water solution of the additive is prepared by introducing the latter to water; then, at mixing clay powder and cement is added in series to the above water; mixture is mixed during at least 30 minutes and then, powder-like polyacrylamide is added; sodium metasilicate is used as an additive, and clay powder providing the yield of clay mortar with viscosity of 20 mPa·s of less than 5.0 m³/t is used as clay powder at the following component ratio, wt %: the above clay powder - 60-80, cement - 15-20, the above additive - 10-20, powder-like polyacrylamide - 0.005-0.01, and water - 100.

EFFECT: creation allows increasing isolating properties of the compound.

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