PLUGGING MATERIAL Russian patent published in 1998 - IPC

FIELD: cementing of oil and gas wells. SUBSTANCE: plugging material includes, wt.-%: gypsum, 3-6; fuel ash, 12-25; portland cement clinker, the balance. Fuel ash is used in the form of fly ash, dump ash of combustion of bituminous or brown coals and/or combustion of oil shales. Ash containing at least 35 wt. -% of SiO₂ and not less than 17.0 wt.-% of Al₂O₃ and portland cement clinker containing 0.5-3.0 wt.-% of free CaO. EFFECT: high-strength plugging material. 3 cl, 2 tbl