Abstract

Symmetrization/antisymmetrization of tensor resistivity measurements and data rotation technique enable separation of the formation response from the tool eccentricity effect in the borehole. Similar principles of data processing can be applied to tensor measurements acquired by both wireline and logging-while-drilling tools of the new generation. I show how to directly determine the bed boundary positions and the formation anisotropy azimuth and how to perform visual interpretation of raw tool data in the presence of the tool eccentricity. I study the tool behavior in conductive water-based mud boreholes — the situation that requires much more complicated numerical modeling than the case of resistive oil-based mud boreholes. I show when and how the tool eccentricity effect can be separated from the formation response. The separation technique can accelerate and improve existing methods of formation interpretation.

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