GROUTING COMPOSITION FOR ISOLATION OF LOST-CIRCULATION ZONES AND A METHOD FOR PREPARATION THEREOF Russian patent published in 2007 - IPC C09K8/467 

FIELD: oil and gas production.

SUBSTANCE: invention relates to drilling boreholes for oil, gas, and water and is basically designed for use in zones with strong and extremely catastrophic losses of drilling fluids but can also be used in zones with normal loss. Grouting composition contains binding base, caustic magnesite, and tempering fluid comprising aqueous solution containing magnesium chloride and chemical additive controlling thickening and setting times, said aqueous solution being, in particular, bischofite solution having density 1.28 g/cc and said chemical additive being, in particular, double superphosphate, while said aqueous solution further contains, as fillers, clay powder and paper production waste (dehydrated sediment from treatment plants). Following proportions of components are used: 42.55-43.08% caustic magnesite, 8.62-10.64% clay powder, 2.34-2.84% paper production waste, 2.38-2.92% double superphosphate, and bischofite solution with density 1.28 g/cc - the rest. Preparation of grouting solution comprises(i) providing tempering fluid, namely aqueous solution containing magnesium chloride, to which above-mentioned chemical additive is added and (ii) tempering above-mentioned caustic magnetite with above-mentioned fillers added at weight ratio of tempering fluid to caustic magnetite with fillers at least 0.8.

EFFECT: enhanced reliability of isolation of lost-circulation zones in finely and macroporous, fractured, cavernous, and mixed rocks by providing high-elasticity, durable, and corrosion-resistant grouting stone exhibiting small expansion.

2 cl, 3 tbl