| 摘要 |
In the representative embodiment of the present invention disclosed herein, a nuclear-magnetism logging tool is arranged with at least its polarizing and detecting coil isolated in an enclosed chamber containing a uniquely-treated hydrogenous oil and preferably coupled to a suitable compensating system operatively arranged for responding to borehole pressure and temperature conditions. In particular, a selected, minor amount of a ferromagnetic colloid is dispersed in the oil in a sufficient concentration for uniquely effecting a controlled decay of nuclear magnetic noise signals from the coil-isolating oil, with this decay being of selected rapidity sufficient to avoid interference with the measurement of nuclear magnetic measurement signals from earth formations.
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