METHOD OF PRODUCTION STRING SEALING Russian patent published in 2015 - IPC E21B33/122 E21B33/124 E21B29/10 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, in particular, to methods of production string sealing. The method of production string sealing includes performance of geophysical survey in the well in order to determine leakage interval in the production string, running in of top and bottom packers to the production string, which are interconnected by a tube at setting tool, setting of top and bottom packers in the well above and below the leakage interval, removal of the setting tool from the well. Upon determination of the leakage interval in the production string above and below of the leakage interval by geophysical survey the top and bottom intervals for production string cutting and length of each interval are defined, from the well mouth to the production string a drill stem complete with bottomhole hydraulic engine and cutter at the end is run in to the well, cutting of the production string is made top-bottom at first in the top cutting interval, then in the bottom cutting interval, the drill stem with bottomhole hydraulic engine and cutter is retrieved to the well mouth, the drill stem with expanding reamer at the end is run in again to the production string, the drill stem is rotated from the well mouth and top-down cleanout of the well is performed from remains of broken cement stone at first in the top cutting interval, then in the bottom cutting interval, thereafter the drill stem with expanding reamer is retrieved from the production string, and the following assembly is assembled bottom-up at the well mouth: mechanical anchor, the lower water swellable packer with length equal to length of the bottom cutting interval in the production string, a pipe equal to distance between the cutting intervals, the upper water swellable packer with length equal to length of the top cutting interval in the production string, centring skid, the left cross-over shoe; then the assembly is run in at the setting tool to the production string so that the upper and lower water swellable packers are placed opposite the to and bottom cutting intervals in the production string, mechanical anchor is dropped and the assembly is unloaded to mechanical anchor, whereupon the setting tool is rotated and disconnected from assembly, the setting tool is retrieved from the production string, at that the assembly remains in the present interval of the production string, process is withhold for the period of the upper and lower packers swelling in the well.

EFFECT: increased reliability and efficiency of the production string sealing, reaching minimum reduction in flow passage of the production string with performance of process operations at the well repair and formation surveying when required.

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