Downhole fishing tool for retrieving metallic debris from a borehole

A downhole fishing tool comprising:

• a main body extending along a longitudinal axis, said body presenting a pair of axially spaced wide outer surfaces;
• and
• a side magnet coupled to the body and axially positioned between the wide outer surfaces,
• said side magnet presenting a generally radially facing side surface,
• said wide outer surfaces being radially spaced from the longitudinal axis by a first maximum radial distance,
• said side surface being radially spaced from the longitudinal axis by a second maximum radial distance,
• said first radial distance being at least 20 percent greater than the second radial distance.

A downhole fishing tool comprising:

• a main body extending along a longitudinal axis, said body presenting a pair of axially spaced wide outer surfaces;
• and
• a side magnet coupled to the body and axially positioned between the wide outer surfaces, said side magnet presenting a generally radially facing side surface,
• said wide outer surfaces being radially spaced from the longitudinal axis by a first maximum radial distance,
• said side surface being radially spaced from the longitudinal axis by a second maximum radial distance,
• said first radial distance being at least 10 percent greater than the second radial distance,
• said side surface being substantially flat.

A downhole fishing tool comprising:

• a main body extending along a longitudinal axis, said body presenting a pair of axially spaced wide outer surfaces;
• and
• a side magnet coupled to the body and axially positioned between the wide outer surfaces, said side magnet presenting a generally radially facing side surface,
• said wide outer surfaces being radially spaced from the longitudinal axis by a first maximum radial distance,
• said side surface being radially spaced from the longitudinal axis by a second maximum radial distance,
• said first radial distance being at least 10 percent greater than the second radial distance
• said body further presenting a narrow outer surface axially positioned between the wide outer surfaces,
• said side magnet being positioned proximate the narrow outer surface,
• said body further presenting a pair of axially spaced tapered outer transition surfaces each axially positioned between an end of the narrow outer surface and an end of a respective wide outer surface,
• said narrow outer surface being radially spaced from the longitudinal axis by a third maximum radial distance,
• said third radial distance being less than the first radial distance.

A downhole fishing tool for retrieving radioactive marker bullets from a borehole extending into a subterranean formation, said downhole fishing tool comprising:

• a main body extending along a longitudinal axis and including axially spaced proximal and distal ends, said body presenting a first wide outer surface proximate the distal end, a third wide outer surface proximate to the proximal end, and a second wide outer surface axially spaced from and positioned between the first and third wide outer surfaces;
• a first group of circumferentially spaced magnets coupled to the body and axially positioned between the first and second wide outer surfaces;
• a second group of circumferentially spaced magnets coupled to the body and axially positioned between the second and third wide outer surfaces;
• and
• a third group of spaced-apart magnets coupled to the distal end of the body,
• each magnet in said first and second groups of magnets presenting a generally radially facing side surface,
• each magnet in said third group of magnets presenting a generally axially facing bottom surface,
• said side surface and said bottom surface being exposed so that when the downhole fishing tool passes by a metallic foreign object located away from the fishing tool, the foreign object can be pulled directly into contact with the side surface or the bottom surface and held against the side surface or bottom surface by magnetic force,
• said wide outer surfaces being generally cylindrical in shape,
• said side and bottom surfaces being substantially flat.

An elongated downhole tool for inserting radioactive marker bullets into a subterranean formation and retrieving stray radioactive marker bullets not properly implanted in the formation, said downhole tool comprising:

• a radioactive marker bullet gun having a normally upper end and a normally lower end;
• and
• a magnetic fishing tool having a proximal end coupled to the normally lower end of the radioactive marker bullet gun and a distal end,
• said fishing tool including side magnet positioned between the proximal and distal ends of the fishing tool and an end magnet positioned proximate the distal end of the fishing tool,
• said side magnet presenting an exposed side surface facing in a first direction and said end magnet presenting an exposed bottom surface facing in a second direction,
• said first direction being within 30 degrees of perpendicular to the direction of extension of a longitudinal axis of the downhole tool,
• said second direction being within 30 degrees of parallel to the direction of extension of the longitudinal axis,
• said side surface and said bottom surface being substantially flat,
• said first and second directions being within 30 degrees of perpendicular to one another.

A wellbore system in a subterranean formation, said wellbore system comprising:

• a borehole extending downward into the subterranean formation;
• a stray radioactive marker bullet loosely positioned in the borehole;
• and
• a fishing tool positioned in the borehole and including a plurality of magnets operable to attract and hold the stray radioactive marker bullet so that the stray radioactive marker bullet can be removed from the borehole along with the fishing tool,
• said fishing tool including a main body extending along a longitudinal axis, said body presenting a pair of axially spaced wide outer surfaces,
• said magnets including a side magnet coupled to the body and axially positioned between the wide outer surfaces,
• said wider outer surfaces being radially spaced from the longitudinal axis by a first maximum radial distance,
• said side surface being radially spaced from the longitudinal axis by a second radial maximum distance,
• said first radial distance being at least 10 percent greater than the second radial distance.