SYSTEM AND METHOD OF FOCUSING AN ARRAY LATEROLOG

摘要

Various embodiments include apparatus and methods to make resistivity measurements in a borehole using tool having an array of electrodes operable to provide focused currents, measure corresponding voltages, and measure corresponding voltage differences to determine resistivity. Tools can be configured to operate at a plurality of modes when voltage differences at some frequencies are effectively unreadable. Additional apparatus, systems, and methods are disclosed.

主权项

1. A method comprising:
generating current from a main electrode of a tool disposed in a borehole at a frequency assigned to the main electrode, the tool having a number of current electrodes spaced apart from each other in a sequence from the main electrode, the tool having two monitor electrodes between the main electrode and a first current electrode of the sequence and two monitor electrodes located next to each other between each of two adjoining current electrodes in the sequence; generating current from each one of the current electrodes in the sequence to a last current electrode in the sequence at a frequency assigned to the current electrode, the assigned frequencies being different from each other, determining voltages at the monitor electrodes in response to the currents generated from the current electrodes in the sequence; determining voltage differences between the two monitor electrodes located next to each other between each of two adjoining current electrodes in the sequence in response to the currents generated; and determining an apparent resistivity based on the determined voltages and the determined voltage differences.