Patent ID: 8756015

Claim:
A method for increasing sensitivity in a measurement of at least one of magnitude and direction of resistivity in an earth formation, the method comprising: performing a first set of measurements of resistivity of the earth formation using a first logging instrument disposed in a first borehole penetrating the earth formation; constructing a model of a background signal derived from a resistivity gradient in the earth formation using the first set of measurements; calculating a predicted response of a second logging instrument to the model of the background signal; performing a second set of measurements of at least one of magnitude and direction of resistivity of the earth formation using the second logging instrument, wherein the second logging instrument is disposed in a second borehole penetrating the same earth formation as the first borehole; deriving a second logging instrument response from the second set of measurements; and subtracting the predicted response from the second logging instrument response to produce a corrected response that has greater sensitivity than the second logging instrument response; wherein the second logging instrument is separate, independent, and configured differently from the first logging instrument.