METHOD OF PRODUCTION STRING SEALING Russian patent published in 2014 - IPC E21B33/138 C09K8/44 

FIELD: oil and gas production industry.

SUBSTANCE: method of production string sealing includes running-in of a tubing string into a production string and setting of the tubing string open end at the depth below the fault zone. The well is filled with the process liquid at that it exits from an annular space to the surface. Then intake of the fault zone is determined. After determination of the intake value a double-component cement composition is selected, density and ratio of the cement composition is determined. The process liquid is circulated at a temperature of 5-10°C and density less or more than the density of the injected double-component cement composition per 5% until the temperature and density stabilise in the tubing string and annular space behind the tubing string. The double-component cement composition with continuous flow is prepared and fed to the tank, at the same time it is fed in a continuous mode to the tubing sting and flushed down by the process liquid at a temperature of 5-10°C and density less or more than the density of the injected double-component cement composition per 5% until liquid columns in the tubing string and annular space behind it come into balance. The tubing string is run out up to the upper border of the double-component cement composition with further removal of the cement composition excess. The double-component cement composition is injected into the fault zone with the flow rate less than 2 l/s. When pressure becomes per 10% lower than the alarm pressure for the production string, injection is stopped and periodical injection of the double-component cement composition is made into the fault zone as the pressure decreases until zero intake value is obtained. Then additional injection is stopped, the pressure in the borehole is decreased smoothly up to 40-60% of the value received in the process of additional injection.

EFFECT: improving efficiency of remedial cementing during sealing of production strings, improving accuracy control over injection of the cement composition planned volume.

1 dwg