DOWNHOLE INNER SPEAR Russian patent published in 2014 - IPC E21B31/20 

FIELD: mining.

SUBSTANCE: proposed device comprises mandrel with top adapter, bottom guide adapter, lengthwise channel and conical surface diverging downward, thrust located above said surface and collet sleeve with conical inside with inner teeth arranged between the thrust and conical surface. Sleeve features OD larger by 2-3 mm than ID of hardware being retracted from the well and is spring loaded from the mandrel thrust. Note here that this sleeve is equipped with one through cut-out and several alternating opposed blind cut-outs to allow sleeve fitting in inner hole of retractable hardware.

EFFECT: higher reliability, simplified design.

2 dwg