METHOD OF LIQUIDATION OF LEAKINESS OF WORKING STRING OF OIL AND GAS RECOVERY WELL Russian patent published in 2008 - IPC E21B33/13 

FIELD: petroleum industry.

SUBSTANCE: invention relates to the oil and gas production industry namely to the method of liquidation of leakiness of the working strings of gas, gas condensate and oil recovery wells located, particularly, in eternal frost zones. The method includes well killing, withdrawal of the oil string, installation of the cement plug below the leakiness interval of the oil string, punching additional perforation holes within the leakiness interval, injection and forcing-through under pressure of the light sealing compound through these holes, injection of expanding cement grout into the well within the interval of additional perforation holes after hardening of light sealing compound, generation of overpressure inside the oil string above the cement plug, drilling through expanding cement grout after it hardened together with the cement plug. Forcing-through of the light sealing compound into the casing annulus of the well is performed under pressure equal to 0.7-0.8 of the pressurisation value for the oil string and the cement plug. The light sealing compound consists of backfill Portland-cement, epoxy-polyurethane polymer "ЭПУ-01-Б", aluminosilicate microspheres, polyvinylchloride, latex, methylchlorosiloxane, "ТМХС" and the hardening agent at a certain ratio of the ingredients. The expanding cement grout consists of backfill Portland-cement, aluminosilicate microspheres, hydrocarboaluminate additive, gypsum, plasticiser and water or 4% solution of calcium chloride at a certain weight ratio of the ingredients. The invention provides increased reliability of liquidation of leakiness of working strings of the gas and oil recovery wells and elimination of channels for overflow of gas, gas condensate, oil or stratal water from the stratum to the well opening.

EFFECT: increased reliability of liquidation of leakiness of working strings of the gas and oil recovery wells and elimination of channels for overflow of gas, gas condensate, oil or stratal water from the stratum to the well opening.

5 dwg, 1 ex