BOREHOLE CASING SPEAR Russian patent published in 2005 - IPC

FIELD: fishing for or freeing objects in boreholes or wells, particularly used during tube damage liquidation inside wells.

SUBSTANCE: spear comprises conical body with guiding means in lower part and sub in upper part thereof, fishing bush and releasing unit. The fishing bush is made as collet provided with slips in lower part thereof and with rest in upper part thereof. The rest has guiding pin fixedly secured to it. Releasing unit is made as figured channel formed on outer surface of conical body. The channel includes alternating short and long groves adapted to cooperate with guiding pin to rotate thereof only in one direction relative conical body when collet reciprocates relative the conical body.

EFFECT: increased structural reliability and possibility to perform all operations under control, increased reliability of spear freeing.

2 dwg