PLUGGING MATERIAL FOR CEMENTING CASING STRING AND METHOD FOR ITS PREPARATION Russian patent published in 2012 - IPC C09K8/467 

FIELD: oil and gas industry.

SUBSTANCE: plugging material for cementing casing string contains binding base-caustic magnesite, magnesium chloride that differs by containing bentonite clay and agent regulating hardening and thickening time sodium tetraborate dehydrate - borax with the following component ratio, wt % caustic magnesite 30.0-40.0, bentonite clay 0.1-8.0, sodium tetraborate dehydrate-borax 0.1-0.5, magnesium chloride 15.0-36.0, water is the rest. Method for preparation of plugging material consists in pre-mixing of mixture of dry substances of binding base - caustic magnesite and filling agent - bentonite clay by prepared water solution of magnesium chloride, in which there preliminary is dissolved agent regulating hardening and thickening time - sodium tetraborate dehydrate - borax.

EFFECT: obtaining magnesian plugging material, the solution of which is characterised by low density, optimal spreadability factors, low indices of water separation and reasonable time of thickening and hardening.

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