LIGHTENED GROUTING CEMENT AND A METHOD FOR PREPARATION THEREOF Russian patent published in 2007 - IPC C09K8/473 E21B33/138 C04B7/52 

FIELD: oil and gas production.

SUBSTANCE: invention is designed for use in cementation of deep oil, gas, and gas condensate boreholes under complicated geologic conditions and on deposits in late development stage, in whose geologic profiles there are intake formations and formations in risk or rupture. Lightened grouting cement containing clinker, natural gypsum-dihydrate, and lightening additive contains, as said lightening additive, tripoly powder or diatomite, or gliezh (fired clay), said lightened grouting cement further containing silica gel and having specific surface 700-900 m²/g and granulometric composition characterized by following sieve residues: 0.315 - 0.1%, 0.25 - 0.1%, 0.16 - 0.2%, 0.1 - 1.5%, 0.08 - 2.1%, and passage through sieve 0.08 - the rest. Finally, lightened grouting cement is composed of, wt %: clinker 55-63, gypsum 5.5, lightening additive 30-38. and silica gel 1-1.5. Method of preparing lightened grouting cement comprises jointly grinding at 300-350°C clinker, gypsum-dihydrate with moisture content 10-12%, lightening additive with moisture content 15-18%, and silica gel until target specific surface is obtained.

EFFECT: reduced setting and structurization period of cement at moderate temperatures, increased strength of stone at early setting period, and reduced power consumption on preliminary drying of lightening additives.

2 cl, 2 tbl