METHOD OF SEALING OF GAS WELL LINING Russian patent published in 2003 - IPC

FIELD: oil-gas producing industry; applicable in repair and isolating jobs in gas, gas-condensate and oil wells in course of their drilling and operation for restoration of gas-tightness of lining, particularly, cement ring. SUBSTANCE: method includes treatment of cement stone by injection in annular space of aqueous solution of electrolyte in form of aluminum sulfate with subsequent building-up of additional pressure. Said treatment is carried out by successive injection of electrolyte in form of sodium silicate with density of 1096-1265 kg/cu.m, separating displacement fluid and aqueous solution of aluminum sulfate with density of 1094-1333 kg/cu.m. Technical result of invention consists in penetration of formed silica sol due to low viscosity of solution into pares and microfractures of cement stone with formation of plugging material in form of silica gel and formation of sodium aliminate directly in formation that provides for recovery of cement stone gas tightness and prevention of crossflows between strings within wider ranges of specific injectivity. EFFECT: higher efficiency of method. 1 tbl