GAS-BLOCKING PLUGGING MATERIAL FOR CEMENTING HORIZONTAL WELLS WITH SMALL ANNULAR GAPS Russian patent published in 2015 - IPC C09K8/467 

FIELD: mining.

SUBSTANCE: plugging material comprises portland cement, microdispersed and expansion additives, fluid loss additive, the setting accelerator and water. The composition comprises the microdispersed and expansion additives as microdispersed cement complex MDCC consisting of: micro-cement or silica, or metakaolin and calcium hydrosulphoaluminate in a weight ratio of 2:1, respectively; the fluid loss additive - as water binding complex WBC consisting of a copolymer vinyl acetate and ethylene with vinyl acetate groups content of 18-20%, hydroxyethyl cellulose and modified organosilicon reagent in a weight ratio of 10:1:0.5, respectively; and the composition comprises the setting accelerator as calcium chloride or sodium chloride, in the following ratio of components, parts by weight: portland cement: 75-95; MDCC 5-25; WBC 2.0-3.5; the said setting accelerator 0.1-3.0; water 47-60.

EFFECT: increase in adhesion, strength characteristics, reduction of filtrate return and dynamic shear stress, improvement of indices of water and gas-blocking properties of the plugging material and formed cement stone.

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