METHOD OF PRODUCTION STRING SEALING Russian patent published in 2014 - IPC E21B33/00 

FIELD: oil and gas industry.

SUBSTANCE: method of production string sealing includes running-in of two packers interconnected by a tube at a setting tool made as a flow column, setting of these packers in production string above and below the sealing failure and further removal of the setting tool. Before occurrence of failure in the production string sealing samples are taken and initial specific weight of the stratum fluid is determined, then at the well head the following assembly is arranged bottom-up: the lower packer, a tube, the upper packer, the left crossover shoe, a dead-ended coupling, a perforated tube; the assembly is run-in at the setting tool to the place of sealing failure occurrence; then the lower packer is seated by its axial movement per 1.5m up and down and the upper packer is seated by unloading of the assembly to the lower packer; then the well over the upper packer is filled with process fluid and the flow column if pressurised under excess pressure that does not exceed permitted pressure on the flow column; the flow column is withhold under excess pressure during 30 minutes and tightness of the upper packer seating is checked; when the upper packer seating is untight the upper and lower packers are unset and the whole assembly is removed for the purpose of its inspection and thereafter all above operations are performed up to tight seating of the upper packer; when the upper packer seating is tight then the setting tool is rotated clockwise, the setting tool is unscrewed and removed together with the perforated tube, the dead-ended coupling and the left crossover shoe from the flow column to the surface; operation of the well is started, samples are taken and specific weight of the stratum fluid is determined; by comparison of the initial and retested value of the stratum fluid specific weight sealing of the lower packer seating is defined; if the lower packer sealing is untight then repeated sealing of the flow column is performed as described above from running-in of the assembly to the place of sealing failure up to determination of tightness for the lower packer seating.

EFFECT: this method of production string sealing allows increasing efficiency and quality of the production string sealing, reducing time for production string sealing; the method is also simple in use as the whole sealing process is performed during one run of the tool.

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