Baker Hughes Corporation

Michael S Crosskno

Stanislav W Forgang

Otto N Fanini

Luis M Pelegri

Randy Gold

Tammye Crosskno, Legal Representative

An induction logging device is provided with additional electrodes. One set of electrodes provides voltages that are indicative of the current distribution in the borehole. The output of the first set of electrodes may be used for estimating formation resistivity. A second set of electrodes may be used to provide an image of the formation.

Method and apparatus for combined induction and imaging well logging

Misalignment of the transmitter and receiver coils of an induction logging tool is determined by positioning the logging tool with a coil axially encompassing the transmitter coil and/or the receiver coil, and activating the transmitter at a plurality of rotational angles.

Correction of misalignment of antennas in a downhole logging tool

The present invention improves measurement of the formation induction response in the presence of the primary magnetic field generated by a logging tool's transmitter. A structure is provided having a new combination of electrical and mechanical design features which provide logging tool for internal calibration and checking of antenna performance and characteristics before during and after well logging operations.

Method and apparatus for internal calibration in induction logging instruments

Calibration of the arrays of a multicomponent induction logging tool is achieved by positioning the tool horizontally above ground. The upper and lower housings of the tool are connected by a borehole conductivity simulator which as a resistance comparable to that of a borehole. Axial and radial positioning of the transmitter coils is done by monitoring outputs at receiver coils to achieve a minimum.

Borehole conductivity simulator verification and transverse coil balancing

Two loop calibrator

A transverse induction logging tool having a transmitter and receiver for downhole sampling of formation properties, the tool having a symmetrical shielded split-coil transmitter coil and a bucking coil interposed between the split transmitter coils to reduce coupling of the transmitter time varying magnetic field into the receiver. The tool provides symmetrical shielding of the coils and grounding at either the transmitter or receiver end only to reduce coupling of induced currents into the received signal. The tool provides an insulator between receiver electronics and the conductive receiver housing having contact with conductive wellbore fluid, to reduce parasitic current flowing in a loop formed by the upper housing, feed through pipe, lower housing and wellbore fluid adjacent the probe housing or mandrel. An internal verification loop is provided to track changes in transmitter current in the real and quadrature component of the received data signal. A galvanic electrode is housed in the same mandrel with the induction logging receiver and transmitter.

Method and apparatus for accurately measuring properties of a formation

The present invention improves measurement of the formation induction response in the presence of the primary magnetic field generated by a logging tool's transmitter. In a exemplary embodiment of the present invention, a structure is provided having a new combination of electrical and mechanical design features which provide logging tool for internal calibration and checking of antenna performance and characteristics before during and after well logging operations. In one aspect of the invention a logging tool is provided comprising a verification winding for coupling a verification signal into the receiver coil.

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Spring, TX, United States of America

Michael S Crosskno