Electromagnetic formation evaluation tool apparatus and method

摘要

Apparatus and methods are described, such as for obtaining information indicative of a formation resistivity using an electromagnetic formation evaluation tool apparatus. For example, the electromagnetic formation evaluation tool apparatus includes exciter electrodes configured to transmit and receive a formation current. A first exciter electrode may be insulated from a conductive apparatus housing and a second exciter electrode may be coupled to the conductive apparatus housing. Monitor electrodes may be insulated from the conductive apparatus housing. A receiver circuit may be coupled to the monitor electrodes and configured to measure a voltage differential between the monitor electrodes. A power amplifier circuit may be coupled to the first exciter electrode and the conductive apparatus housing and configured to generate the formation current wherein the conductive apparatus housing provides a return path to the power amplifier circuit for the formation current.

主权项

1. An electromagnetic formation evaluation tool apparatus comprising:
a plurality of exciter electrodes configured to transmit and receive formation currents, the plurality of exciter electrodes comprising:
a first exciter electrode insulated from a conductive apparatus housing that is insulated from a borehole environment; anda second exciter electrode coupled to the conductive apparatus housing; a plurality of monitor electrodes insulated from the conductive apparatus housing, the plurality of monitor electrodes located around the periphery of the conductive housing and between the first and second exciter electrodes; a receiver circuit coupled to the plurality of monitor electrodes and configured to measure a voltage differential between the plurality of monitor electrodes; and a power amplifier circuit coupled to the first exciter electrode and the conductive apparatus housing and configured to generate the formation current, wherein the conductive apparatus housing provides a return path to the power amplifier circuit for the formation current.