METHOD OF PRODUCTION STRING SEALING Russian patent published in 2014 - IPC E21B33/122 

FIELD: oil and gas industry.

SUBSTANCE: sealing method of a production string involves lowering on a setting tool to a production string of the well of two packers connected between with a pipe, their setting in the production string above and below the leakage interval with further removal of the setting tool and sealing of the production string. Prior to sealing, bed is temporarily locked by self-decomposing after checking the bottom packer tightness. After that the following components are assembled at well mouth, from bottom to top: the lower packer, a tube the upper packer, hydraulic disconnector; the packing is run-in at the setting tool to the place of sealing failure occurrence; then the packer are successively seated. First the lower packer is seated by its axial movement per 1.5-2 m up and down and then the upper packer is seated by unloading of the packing to the lower packer. After that a geophysical tool on the cable is run in at the setting tool to the point of the lower packer location and sealing of the lower packer seating is checked, carrying out geophysical study; then the geophysical tool on the cable is removed from the well; tubing-casing annulus above the upper packer is filled with process fluid and the flow column is 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; in case setting of both packers is tight, the hydraulic disconnector is actuated; for this, ball is thrown from the well head into the setting tool, the setting tool is filled with process fluid and excessive pressure of fluid is created in it until actuation of the hydraulic disconnector; after that, the setting tool with the hydraulic disconnector is removed from the flow column to the surface; in case of untight seating of at least one packer both packers are unset and the whole packing is removed for inspection, thereafter all the above operations of temporarily blocking, downing, setting and testing are repeated. The suggested method of production string sealing is simple as far as the whole sealing process is carried out during one tool running. There is a possibility to control tightness of upper packer seating until its disconnection from the setting tool. Also two-packer unit can be removed to the well head in case of untight seating of the upper packer until disconnection of the setting tool.

EFFECT: increased efficiency and success of works on sealing of flow columns with two-packer units in directional wells.

5 dwg, 1 tbl