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US 4,071,815 AGranted
Well logging system for measuring remanent magnetic fields in the earth
AssigneeMobil Oil Corporation
InventorJoseph Zemanek, Jr.
Life of this patent
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AssigneeMobil Oil Corporation
InventorJoseph Zemanek, Jr.
Estimating the term…
A borehole tool for logging the remanent magnetic field of the earth formations surrounding a borehole includes a coil system having transmitter, receiver, and nulling coils; a phase-sensitive detector connected across the receiver and nulling coils to provide signals representative of magnetic susceptibility; and a detector system having a pair of axially spaced magnetometers, a pair of counters, an oscillator, a comparator, and a transmitter to provide signals representative of the total magnetic field differential between the two magnetometers. An uphole receiver compares differentials in the magnetic susceptibility measurements between two positions in the borehole with the total magnetic field differential between the same two positions as an indication of the earth's remanent magnetic field.
A method for determining paleomagnetic reversals between subsurface formations traversed by a borehole, comprising the steps of:
A borehole logging system for detecting paleomagnetic reversals in subsurface formations traversed by a borehole, comprising:
Dependencies are inferred from the claim text.