Method and Apparatus for Detection and Quantification of Borehole Standoff
AssigneeWeatherford Technology Holdings, LLC
InventorDavid Gouyu Hu
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Abstract
A method of quantifying borehole properties, comprising: injecting an electric current from an outer button and an inner button disposed on an equipotential pad into a subterranean formation surround by the borehole, measuring an apparent conductivity or a scaled current for each button, modeling the measurements at a sequence of standoff locations, and, using an inversion technique to determine at least one of the following borehole properties: mudcake thickness, mudcake resistivity, diameter of invasion, flushed zone resistivity and true formation resistivity.
Claims24
A method of logging a subterranean formation surrounding a borehole, the method comprising:
- injecting an electric current from buttons disposed on an equipotential pad into the formation surrounding the borehole, the buttons including at least two outer buttons and one or more inner buttons;
- collecting a first electrical measurement from each button;
- modeling the first electrical measurements at a sequence of standoff locations;
- and
- determining at least one downhole property by using an inversion technique on the modelled measurements.
A downhole logging apparatus for a subterranean formation surrounding a borehole, the apparatus comprising:
- a return electrode associated with the apparatus;
- an equipotential pad associated with the apparatus;
- a plurality of buttons disposed on the equipotential pad and including at least two outer button and one or more inner buttons;
- and
- processing circuitry associated with the apparatus and monitoring the buttons and the return electrode, the processing circuitry being configured to:
- inject an electric current from the buttons into the subterranean formation surrounding the borehole,
- collect a first electrical measurement from each button,
- model the first electrical measurements at a sequence of standoff locations, and
- use an inversion technique on the modelled measurements to determine at least one downhole property.
Dependencies are inferred from the claim text.