Abstract: A current regulator for regulating alternating current (AC) flow to a load device is provided. The current regulator can include an AC coupling device that can be electrically connected to the load device via an output electrical path, a current control device electrically connected in series with the AC coupling device, and an AC feedback circuit electrically connected to the output electrical path and the current control device. The current control device can modify a current flow through at least one component of the AC coupling device in response to receiving an error correction current. An output AC current provided to the load device can be controlled based on the current flow through the component of the AC coupling device. The AC feedback circuit can include voltage error compensation device that provides the error correction current in response to receiving a feedback voltage corresponding to the output AC current.

Abstract: A resistivity logging tool includes a plurality of excitation electrodes, at least one return electrode, and a plurality of monitor electrodes. The resistivity logging tool also includes a controller that determines a set of independent currents to be emitted by at least some of the plurality of excitation electrodes during an excitation cycle based on at least one measured downhole parameter and at least one predetermined constraint.

Abstract: A resistivity logging system includes a plurality of excitation electrodes, at least one return electrode, and a plurality of monitor electrodes. The resistivity logging system also includes a controller that determines a level of excitation current to be emitted by at least one of the plurality of excitation electrodes during a subsequent excitation cycle based on a comparison of measured downhole parameter values corresponding to excitation current emitted in two previous excitation cycles.

Abstract: A resistivity logging tool includes a plurality of excitation electrodes, at least one return electrode, and a plurality of monitor electrodes. The resistivity logging tool also includes a controller that determines a set of independent currents to be emitted by at least some of the plurality of excitation electrodes during an excitation cycle based on at least one measured downhole parameter and at least one predetermined constraint.

Abstract: A current regulator for regulating alternating current (AC) flow to a load device is provided. The current regulator can include an AC coupling device that can be electrically connected to the load device via an output electrical path, a current control device electrically connected in series with the AC coupling device, and an AC feedback circuit electrically connected to the output electrical path and the current control device. The current control device can modify a current flow through at least one component of the AC coupling device in response to receiving an error correction current. An output AC current provided to the load device can be controlled based on the current flow through the component of the AC coupling device. The AC feedback circuit can include voltage error compensation device that provides the error correction current in response to receiving a feedback voltage corresponding to the output AC current.

Abstract: A resistivity logging system includes a plurality of excitation electrodes, at least one return electrode, and a plurality of monitor electrodes. The resistivity logging system also includes a controller that determines a level of excitation current to be emitted by at least one of the plurality of excitation electrodes during a subsequent excitation cycle based on a comparison of measured downhole parameter values corresponding to excitation current emitted in two previous excitation cycles.

Abstract: Technologies are described for reducing distortion in amplified signals in well logging tools based on spectral analyses of the amplified signals. For example, a system includes a well logging tool. The well logging tool includes an excitation source to direct an excitation signal towards an environment adjacent a wellbore and a receiver to amplify a probe signal received from the environment adjacent the wellbore in response to the excitation signal. The system also includes a feedback module to receive the amplified signal. The feedback module includes a spectrum analyzer module to spectrally analyze the amplified signal to generate spectral information of the amplified signal; and a controller module to determine, from the spectral information, whether the amplified signal includes distortion, and if so, to issue a feedback signal to the excitation source or the receiver to cause at least a reduction of the distortion in the amplified signal.

Abstract: Technologies are described for reducing distortion in amplified signals in well logging tools based on spectral analyses of the amplified signals. For example, a system includes a well logging tool. The well logging tool includes an excitation source to direct an excitation signal towards an environment adjacent a wellbore and a receiver to amplify a probe signal received from the environment adjacent the wellbore in response to the excitation signal. The system also includes a feedback module to receive the amplified signal. The feedback module includes a spectrum analyzer module to spectrally analyze the amplified signal to generate spectral information of the amplified signal; and a controller module to determine, from the spectral information, whether the amplified signal includes distortion, and if so, to issue a feedback signal to the excitation source or the receiver to cause at least a reduction of the distortion in the amplified signal.