Texaco Inc.

James A Fuchs

Larry Wayne Thompson

Percy T Cox

Richard A Meador

Larry L Adams

James R Bridges

A system operating at radio frequencies in the range of 10 MHZ to 60 MHZ is provided for simultaneously determining the resistivity and dielectric constant of earth formations in the vicinity of a well bore. A transmitter coil and two longitudinally spaced receiver coils are provided in the system. Circuit means for measuring the unnormalized amplitude ratio and the relative phase shift of electromagnetic waves at the spaced receiver coils are provided. A relationship is given whereby the formation dielectric constant and resistivity may be obtained from the amplitude ratio and relative phase shift measurements.

Electromagnetic wave logging system for determining resistivity and

The invention disclosed herein includes methods and apparatus for determining true formation resistivity, flushed zone resistivity and invasion diameter of the earth formation in the vicinity of a well borehole. A radio frequency electromagnetic field in the frequency range from 800 kilohertz to 4 megahertz is generated in a borehole and the electromagnetic field is detected at a plurality of longitudinally spaced locations. Measurements of the attenuation and propagation velocity of the electromagnetic wave at the longitudinally spaced receivers may then be interpreted according to predetermined relationships in terms of the formation resistivity, flushed zone resistivity and invasion diameter surrounding the borehole.

Electromagnetic wave propagation well logging utilizing multiple phase

A dielectric well logging system includes a logging tool adapted to be passed through a borehole traversing an earth formation. The logging tool includes a transmitter which induces electric energy into the earth formation at a radio frequency. Two receivers in the logging tool spaced a predetermined distance apart provides intermediate frequency signals corresponding to the electrical energy received from the earth formation. The intermediate frequency signals are transmitted by way of a cable to the surface. Surface electronics include zero crossing detectors, each detector receives a different intermediate frequency signal from the cable and provides a detector signal whose change in amplitude is representative of the intermediate frequency signal passing through zero. A source provides clock pulses at a frequency substantially greater than the frequency of the intermediate frequency signals. A logic circuit receiving the detector signals and the clock pulses provides groups of clock pulses in accordance with the detector signals. The number of clock pulses in each group corresponds to the dielectric constant of the earth formation.

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Missouri City, TX, United States of America

James A Fuchs