METHOD OF WELL KILLING AND VISCO-ELASTIC COMPOSITION FOR ITS REALISATION Russian patent published in 2016 - IPC E21B43/22 C09K8/42 

FIELD: construction.

SUBSTANCE: visco-elastic composition - VEC for well killing, including, wt %: cellulose ester - CE 0.8-2.5, alkaline metal hydroxide 0.1-0.7, complexing compound - soluble salt of aluminium or copper 0.19-0.6, internal decomposer - encapsulated sodium percarbonate or perborate 0.1-0.2, filler - sodium chloride or potassium chloride, or calcium chloride, or sodium nitrate, or reagent MNK 6.5-22.0, pH regulator - acetic or oxalic acid or citric acid 0.02-0.3, water-retaining water-repellent agent - ethylene glycol and/or glycerine, or higher dioxane alcohols 2.0-6.6, water - balance. In the well killing method they inject mineralised water buffer, then the specified VEC by the simultaneously-separate injection of composition 1, containing 50% of the total quantity of CE, around 50% of the total quantity of water and alkaline metal hydroxide, and composition 2, containing the remaining quantity of CE, other water quantity, filler, complexing compound, pH regulator, internal decomposer and water-retaining water-repellent agent, and then an activating compound - AC, containing, wt %: citric or sulphamic acid 5-10, peroxide compound - potassium persulphate or ammonium persulphate, or urea hydrogen peroxide 5-10, non-ionic agent - Neonol AF_9-12 or Sinoksol of grade B, or Reversmol of grade B 0.02-0.03, emulsion breaker - Dissolvan 4411 or SNPH-4802 0.05-0.2, water - balance, with the ratio of AC:VEC equal to 1:3-4. The invention is developed in depending claims.

EFFECT: increased efficiency of well killing with the preservation of reservoir permeability and porosity properties.

7 cl, 5 tbl