Magnetic assembly for use with a downhole casing perforator

A magnetic assembly for use below a perforator tool in a well lined with a metal casing, comprising:

• a pipe section having a series of magnets mounted therewithin in longitudinally-spaced relation, the pipe section having a threaded distal end and a threaded proximal end;
• a guide shoe having a first end threadedly mounted on the distal end of the pipe section, the guide shoe having a rounded tapering nose on a second end and having a central body and a series of equiangularly-spaced vanes extending from the central body, the vanes being sized such that an outer radial extremity of each vane is in use in close proximity to an inside face of the metal casing and a flow passage extends between adjacent pairs of the vanes;
• and,
• a thread adaptor having a first end threadedly mounted on the proximal end of the pipe section, the thread adaptor having a second end adapted to connect to a central position on a bottom face of the perforator tool in use;
• wherein the pipe section is thereby maintained in a generally centred position within the metal casing such that a generally annular flow passage is created between the pipe section and the metal casing, and wherein, after the perforator tool has perforated the metal casing at a location within a resource cavity, fragments of metal carried through the annular flow passage by resulting fluid flow are magnetically pulled toward, and held on, an outside surface of the pipe section.