| 摘要 |
A magnetic tool for retrieving metal objects from a wellbore has a plurality of magnet assemblies spaced longitudinally along a tool body. Each magnet assembly has a plurality of magnet members covering a majority surface area of the tool body. Each magnet member has a magnet body and a shield encasing the magnet body and protecting the individual magnet body from striking force created by the attracted metal particles. The shield is preferably made from a non-ferrous material and allows concentration of the magnetic force away from the tool body and into the casing annulus.
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