Dual mode balancing in OBM resistivity imaging

摘要

Methods, systems, and devices for evaluating an earth formation. Methods may include conveying the carrier into a formation borehole; and using measure electrodes, in one mode of measurement, to make current measurements by applying a voltage to each measure electrode in a first set of sensor arrays while making first current measurements; and applying another high frequency voltage to each measure electrode in a second set of sensor arrays while making second current measurements. Optionally, methods include using the measure electrodes, in another mode of measurement, to make further resistivity measurements by applying a voltage to each measure electrode in both sets of sensor arrays while making third current measurements. Methods include combining first current measurements, second current measurements, and third current measurements to simulate a virtual impedance for each measure electrode. Optionally, any two consecutive sensor arrays around the circumference of the tool body are in different sets.

主权项

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.