PROCEDURE FOR RECOVERY OF TIGHTNESS IN FLOW STRING OF WELL Russian patent published in 2011 - IPC E21B33/13 

FIELD: oil and gas production.

SUBSTANCE: procedure for tightness recovery in flow string of well consists in successive pumping liquid glass and water solution of calcium chloride into isolation zone. Further, there is performed grout torqueing. First, there is pumped fringe of fresh water. Liquid glass and water solution of calcium chloride are pumped with fringes starting from fringe of water solution of calcium chloride. Buffer fringe of fresh water is pumped between each fringe. Water solution of calcium chloride has density 1.30-1.38 g/cm³. Volume ratio between water solution of calcium chloride and liquid glass in fringes is set from 1: 1 to 1: 3. Amount of fringes of water solution of calcium chloride and liquid glass is set not less, than 2. Fringes of water solution of calcium chloride and liquid glass are pressurised with process fluid of 1.00-1.18 g/cm³ density. The well is flushed with process fluid of 1.00-1.18 g/cm³ density and there is performed process conditioning during 2-4 hours. Buffer fringe of fresh water is pumped prior to grout pumping. Upon grout pumping grout is pressurised with process fluid of 1.00-1.18 g/cm³ density, the well is flushed with process fluid of 1.00-1.18 g/cm³ density and process conditioning is carried out for 24-28 hours.

EFFECT: increased reliability of tightness recovery procedure.

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