Texaco Inc.

Donald L Johnson, Jr

Wayne F Warren

Percy T Cox

Theodore W Nussbaum

The present invention is a thin bed resistivity well logging system and method which includes a transmitter transmitting electromagnetic energy into an earth formation, from within a borehole traversing the earth's formation, at a frequency lying within a range of frequencies from 500 kilohertz to 4 megahertz. The system, a portion of which is located in the borehole, determines the true resistivity of a thin strata in accordance with the transmitted electromagnetic energy that has propagated through the earth's formation.

Electromagnetic propagation thin bed resistivity well logging system and

A well logging system and method of the present invention determines the dielectric constant and/or conductivity of earth formations some of which have fluid invasion. The system and method of the present invention includes the transmission of electromagnetic energy into the earth formation from a first location in a borehole in the formations at a frequency which enables the electromagnetic energy to propagate throughout the surrounding earth formations. Electromagnetic energy is received by receivers at three locations in the borehole which are spaced longitudinally from the location of the transmission of the electromagnetic energy. The receivers provide signals representative of the total electromagnetic fields at those locations. The dielectric constant and/or resistivity of the earth formations are determined in accordance with portions of the signals from the three receivers corresponding to secondary electromagnetic fields at the three receiving locations.

Deep penetration well logging system and method

An electromagnetic energy well logging system and method includes transmitting electromagnetic energy substantially at a frequency of 4 MHz into an earth formation from a borehold traversing the earth formation. The true resistivity of an oil-based flushed zone of the earth formation is derived in accordance with the transmitted electromagnetic energy after it is passed through at least a portion of the oil-based flushed zone.

Oil-based flushed zone electromagnetic well logging system and method

Apparatus for determining the dielectric constant and/or resistivity of earth formations traversed by a borehole includes a transmitter which transmits electromagnetic energy into the earth formation from a first location in the borehole at a frequency which enables the electromagnetic energy to propagate throughout the surrounding earth formations. Receivers receive electromagnetic energy at two locations in the borehole which are spaced longitudinally from the transmitter provide signals representative of the total electromagnetic fields at the receiver locations. Circuitry determines the dielectric constant and/or resistivity of the formations in accordance with a secondary field ratio and a phase difference derived from the signals provided by the receivers.

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Houston, TX, United States of America

Donald L Johnson, Jr