05781436 is referenced by 93 patents and cites 12 patents.

A method of measuring the conductivity of earth formations penetrated by a wellbore. The method comprises selectively passing an alternating current through transmitter coils inserted into the wellbore. Each of the transmitter coils has a magnetic moment direction different from the magnetic moment direction of the other ones of the transmitter coils. The alternating current includes a first and a second frequency. The amplitude at the first frequency has a predetermined relationship to the amplitude at the second frequency. The relationship corresponds to the first and the second frequencies. The method includes selectively receiving voltages induced in a receiver coil having a sensitive direction substantially parallel to the axis of the corresponding transmitter coil through which the alternating current is passed. A difference in magnitudes between a component of the received voltage at the first frequency and a component of the voltage at the second frequency is measured, and conductivity is calculated from the difference in magnitudes of the components of the received voltage at the two frequencies. In a preferred embodiment, the step of measuring the difference in magnitudes between the voltage components at the two frequencies includes extracting digital signal samples of the received voltage at predetermined times with respect to a cycle of the transmitter current at the first frequency.

Title
Method and apparatus for transverse electromagnetic induction well logging
Application Number
8/686848
Publication Number
5781436
Application Date
July 26, 1996
Publication Date
July 14, 1998
Inventor
Leonty A Tabarovsky
Houston
TX, US
Otto N Fanini
Stafford
TX, US
Stanislav Forgang
Houston
TX, US
Agent
Richard A Fagin
Assignee
Western Atlas International
TX, US
IPC
G06F 19/00
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