Patent ID: 9121963
Filing Date: 2015-09-01
Classification: E21B,G01V

Abstract:
1. A method for evaluating an earth formation intersected by a borehole using a carrier associated with measure electrodes on a plurality of sensor arrays including a first set of sensor arrays and a second set of sensor arrays, wherein each sensor array of the plurality of sensor arrays includes at least one measure electrode of the measure electrodes, the method comprising: conveying the carrier into the borehole; and using the measure electrodes, in a first mode of measurement, to make first current measurements indicative of a resistivity parameter of the earth formation, wherein the first current measurements are made by applying a first voltage to each measure electrode in the plurality of sensor arrays while making the first current measurements; and using the measure electrodes, in a second mode of measurement, to make further current measurements indicative of the resistivity parameter of the earth formation, comprising: applying a second voltage to each measure electrode in the first set of sensor arrays while making second current measurements; and applying a third voltage that is the opposite polarity of the second voltage to each measure electrode in the second set of sensor arrays while making third current measurements; and combining the first current measurements, the second current measurements, and the third current measurements to simulate a virtual impedance for each measure electrode.