DOWNHOLE FISHING TOOL Russian patent published in 2007 - IPC E21B31/08 

FIELD: oil and gas industry, particularly fishing for or freeing objects in boreholes or wells, namely for removing damaged strings from cavernous wells.

SUBSTANCE: fishing tool comprises body with axial channel and stepped outer surface, through bell and milling crown fixedly connected to the body, guiding means with end slot for damaged pipe string receiving connected to the body by means of shear member and damaged string centrator arranged in milling crown interior. The guiding means is provided with fixing unit to retain the guiding means with respect to well wall. Minimal inner centrator diameter is less than inner diameter of lower through bell end. Fixing unit of guiding means is made as barrel-type rollers grouped in several rows. Each barrel-type roller may rotate about horizontal pin secured in openings formed in side surface of guiding means. Rollers have curvature radius in plane view of not less than well diameter in area of damaged string head location.

EFFECT: increased reliability and efficiency, decreased time of fishing work performing.

3 cl, 2 dwg