A free fluid log. A well log that is dependent on the alignment of the magnetic moment of protons (hydrogen nuclei) with an impressed magnetic field. Protons tend to align themselves with the magnetic field; and when it is removed, they precess in the earth's magnetic field and gradually return to their original state. Proton precession in free fluid produces a radio frequency signal. The amplitude of this radio frequency signal is measured in the nuclear magnetism log as the free fluid index. The rate of decay of the precession signal depends on interactions with neighboring atoms and hence on the nature of the molecule of which the proton is a part. The signal from the borehole fluid decays very rapidly when disseminated iron is present (artificially introduced, or from steel worn from drill pipe and bits). By slightly delaying the time of measuring, the hole signal is minimized. Fluids bound to surfaces (as water adsorbed to clays and silts) and dead oil do not give appreciable response. Thus, the free fluid index indicates the free fluid (the hydrogen in free-fluid hydrocarbons and water). Gas gives a low signal because of its low hydrogen content.
terms:nuclear_magnetism_log
terms/nuclear_magnetism_log.txt · Last modified: 2023/11/22 08:42 by 127.0.0.1