METHOD OF REPAIRING WELLS OF UNDERGROUND RESERVOIRS Russian patent published in 2009 - IPC E21B29/00 E21B33/13 

FIELD: mining.

SUBSTANCE: while implementing method, well is preliminary filled with saturated water solution of common salt with density 1180-1200 kg/m³ to base surface of artificial bottomhole, then lower part of flow string is perforated by making four diametrical openings of 20 mm diameter. The artificial bottomhole is set by means of pumping return emulsion, containing filler - polypropylene fiber- at amount of 0.03-0.05 wt % from the volume of return emulsion, and by pumping cement grout with density 900-1000 kg/m³, made on mineralised water, in volumes facilitating formation of columns 10 m each in an open borehole of the well; then the well is held for the period of cement hardening. An additional casing column is lowered and cemented to the well head. Before pumping the cement grout in the middle part of the interval of its location three circular grooves of 15 cm depth are made at the distance of 1 m one from another. After holding the well for cement hardening the borehole of the well is expanded and its diameter is increased in interval from the top of the artificial bottomhole to the base of the flow string. Tamping the lower part of the flow string is performed by supplying cement grout with density 1840-1900 kg/m³ made on mineralised water in volume calculated from formula. The well is held for cement hardening with following boring a cement column at a depth facilitating setting of the shoe of the additional casing column lower, than the shoe of the flow string.

EFFECT: upgraded quality of pressure tightness restoration of column.

2 cl