Abstract: An apparatus includes a logging cable with exactly 3 conductors and an armor. A first transceiver is coupled to the three conductors and the armor of the logging cable. The first transceiver comprises a first-transceiver mode M1 port, a first-transceiver mode M2 port, and a first-transceiver mode M3 port. The first transceiver couples to a first mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports, a second mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports, and a third mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports. The first mode, the second mode, and the third mode are mutually orthogonal.

Abstract: Apparatus and systems, as well as methods, operate to acquire downhole data associated with a borehole casing, process a portion of the downhole data at a downhole location to provide processed data, and regulate surface motor power received at a motor downhole. The surface motor power is filtered and the processed data is transmitted to a surface location on a monoconductor that also carries the surface motor power. Additional apparatus, systems, and methods are disclosed.

Abstract: In some embodiments, apparatus and systems, as well as methods, may operate to acquire downhole data associated with a borehole casing, process a portion of the downhole data at a downhole location to provide processed data, regulate surface motor power received at a motor downhole, filter the surface motor power, and transmit the processed data to a surface location on a monoconductor that also carries the surface motor power. Additional apparatus, systems, and methods are disclosed.

Abstract: Oil-based mud imaging systems and methods having standoff compensation. In some embodiments, disclosed logging systems include a logging tool in communication with surface computing facilities. The logging tool is provided with a sensor array having at least two voltage electrodes positioned between two current electrodes energized by an excitation source to create an oscillatory electric field in a borehole wall. The two current electrodes are each shielded with conductive shields to prevent current leakage into the logging tool body. A common mode voltage is measured, and the phase and amplitude of the excitation source is controlled to reduce the difference between the common mode voltage and reference voltage of a voltage detector. The logging tool is further provided with electronics coupled to the voltage detector and the current electrodes to determine a differential voltage between the voltage electrodes and two current flows from separate ones of the current electrodes.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include receiving shunt current in one or more conductors according to a sensed component of power distributed by the conductors through one or more transformers coupled to the conductors and determined by an inductance associated with the transformers and a capacitance associated with the conductors.

Abstract: Improved communication systems and methods are disclosed. In one embodiment, a downhole communications system comprises a downhole transceiver and a surface transceiver. The surface transceiver receives a discrete multi-tone (DMT) modulated uplink signal from the downhole transceiver, and transmits a downlink signal to the downhole transceiver using a modulation method determined by the transceivers as communications are initiated. The downlink modulation methods supported by the surface transceiver may include DMT modulation and quadrature amplitude modulation (QAM). The modulation mode selection may be based on measured channel characteristics, on proposed data rates, or on other predetermined parameters. The uplink and downlink signals may be communicated over a shared transmission mode on multiconductor cable or wired pipe, and alternatively the uplink and downlink signals may be communicated over separate transmission modes.

Abstract: A transmission system between a voltage source and a wireline tool comprising a first loop to transmit a signal between the voltage source and the wireline tool. The first loop has a first transformer coupled to the voltage source. The system also comprises a second loop, electrically independent of the first loop, to transmit the signal between the voltage source and the wireline tool. The second loop has a second transformer coupled to the voltage source. If the first loop fails, the first transformer is isolated from the voltage source.

Abstract: Oil-based mud imaging systems and methods having standoff compensation. In some embodiments, disclosed logging systems include a logging tool in communication with surface computing facilities. The logging tool is provided with a sensor array having at least two voltage electrodes positioned between two current electrodes energized by an excitation source to create an oscillatory electric field in a borehole wall. The two current electrodes are each shielded with conductive shields to prevent current leakage into the logging tool body. A common mode voltage is measured, and the phase and amplitude of the excitation source is controlled to reduce the difference between the common mode voltage and reference voltage of a voltage detector. The logging tool is further provided with electronics coupled to the voltage detector and the current electrodes to determine a differential voltage between the voltage electrodes and two current flows from separate ones of the current electrodes.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include receiving shunt current in one or more conductors according to a sensed component of power distributed by the conductors through one or more transformers coupled to the conductors and determined by an inductance associated with the transformers and a capacitance associated with the conductors.

Abstract: A power delivery system for a wireline tool includes two independent power transmission loops operating on a standard six-conductor cable. The two loops each connect directly to a respective terminals of a DC auxiliary power supply. Each loop also couples through a transformer to an AC instrument power supply. Another transformer for telemetry signals facilitates bidirectional communication between the downhole tool and an uphole computer.

Abstract: A method and a downhole telemetry system a downhole telemetry system using discrete multitone modulation for transmitting a data stream over a plurality of transmission modes is provided. The downhole telemetry system includes a downhole transmitter, a cable, and a surface receiver. The downhole transmitter is configured to transmit the data stream over the plurality of transmission modes. The surface receiver is coupled to the downhole transmitter via the cable and is configured to combine signals from each of the plurality of transmission modes to obtain the data stream transmitted by the downhole receiver. The method includes receiving a plurality of signals over the plurality of transmission modes from a downhole package, and may further include combining the plurality of signals to form at least one data stream.

Abstract: A downhole telemetry system having a surface transceiver, a cable, and a downhole transceiver coupled to the surface transceiver via the cable. The surface transceiver isolates an uplink signal from a combined uplink/downlink signal on the cable using time-domain signal cancellation. The downhole transceiver isolates a downlink signal from the combined uplink/downlink signal using time-domain signal cancellation. In the surface transceiver, the time-domain signal cancellation may be performed by running the combined uplink/downlink signal through a coil of a transformer while running a copy of the downlink signal through an opposite coil of the transformer. Likewise, in the downhole transceiver, the time-domain signal cancellation may be performed by running the combined uplink/signal through a coil of a transformer while running a copy of the uplink signal through an opposite coil of the transformer.

Abstract: A transmission system between a voltage source and a wireline tool comprising a first loop to transmit a signal between the voltage source and the wireline tool. The first loop has a first transformer coupled to the voltage source. The system also comprises a second loop, electrically independent of the first loop, to transmit the signal between the voltage source and the wireline tool. The second loop has a second transformer coupled to the voltage source. If the first loop fails, the first transformer is isolated from the voltage source.

Abstract: Improved communication systems and methods are disclosed. In one embodiment, a downhole communications system comprises a downhole transceiver and a surface transceiver. The surface transceiver receives a discrete multi-tone (DMT) modulated uplink signal from the downhole transceiver, and transmits a downlink signal to the downhole transceiver using a modulation method determined by the transceivers as communications are initiated. The downlink modulation methods supported by the surface transceiver may include DMT modulation and quadrature amplitude modulation (QAM). The modulation mode selection may be based on measured channel characteristics, on proposed data rates, or on other predetermined parameters. The uplink and downlink signals may be communicated over a shared transmission mode on multiconductor cable or wired pipe, and alternatively the uplink and downlink signals may be communicated over separate transmission modes.

Abstract: A system and method for downhole power delivery. In one embodiment, the system delivers computer-regulated downhole power voltages, and may be configured to customize signal waveforms and power allocation on the various independent signal transmission modes to maximize the power capacity of the logging cable subject to its maximum voltage rating. In one embodiment, the system includes a standard multiconductor logging cable which supports orthogonal signal transmission modes on circumferentially spaced insulated conductors. A high-power power source on the surface is coupled to the insulated conductors in the cable to drive a power signal on the lowest impedance signal transmission mode. The system may further include multiple power sources operating on different independent signal transmission modes, and may also include multiple telemetry channels which share the power transmission modes via frequency multiplexing.

Abstract: A downhole telemetry system having a surface transceiver, a cable, and a downhole transceiver coupled to the surface transceiver via the cable. The surface transceiver isolates an uplink signal from a combined uplink/downlink signal on the cable using time-domain signal cancellation. The downhole transceiver isolates a downlink signal from the combined uplink/downlink signal using time-domain signal cancellation. In the surface transceiver, the time-domain signal cancellation may be performed by running the combined uplink/downlink signal through a coil of a transformer while running a copy of the downlink signal through an opposite coil of the transformer. Likewise, in the downhole transceiver, the time-domain signal cancellation may be performed by running the combined uplink/signal through a coil of a transformer while running a copy of the uplink signal through an opposite coil of the transformer.

Abstract: A downhole telemetry system having a surface transceiver, a cable, and a downhole transceiver. The downhole transceiver transmits a first category of data over a first set of frequency subchannels and a second category of data over a second set of frequency subchannels. The frequency subchannels of the first set preferably have lower error rate than the frequency subchannels of the second set. The first category of data may include data from a tool, data from a group of sensors within a tool, data sampled from a data stream at a pre-determined frequency, or a combination thereof. In at least some embodiments, the first and second sets of frequency subchannels are at lower frequencies than a third set of frequency subchannels allocated for downlink communications.

Abstract: A method and a downhole telemetry system a downhole telemetry system using discrete multitone modulation for transmitting a data stream over a plurality of transmission modes is provided. The downhole telemetry system includes a downhole transmitter, a cable, and a surface receiver. The downhole transmitter is configured to transmit the data stream over the plurality of transmission modes. The surface receiver is coupled to the downhole transmitter via the cable and is configured to combine signals from each of the plurality of transmission modes to obtain the data stream transmitted by the downhole receiver. The method includes receiving a plurality of signals over the plurality of transmission modes from a downhole package, and may further include combining the plurality of signals to form at least one data stream.

Abstract: A power delivery system for a wireline tool includes two independent power transmission loops operating on a standard six-conductor cable. The two loops each connect directly to a respective terminals of a DC auxiliary power supply. Each loop also couples through a transformer to an AC instrument power supply. Another transformer for telemetry signals facilitates bidirectional communication between the downhole tool and an uphole computer.

Abstract: A digital communications system employing modulated Walsh functions to convey data across a communications channel. In one embodiment, the system includes a transmitter having a constellation encoder, and a Walsh constellation modulator. The constellation encoder receives a sequence of data words and converts it into a sequence of constellation signal point labels. The modulator receives the sequence of labels, and responsively generates one or more amplitude-modulated Walsh functions which are summed to produce a modulated signal. The modulated signal passes through a communications channel to a receiver. The receiver includes an analog-to-digital converter (ADC) and a demodulation circuit. The ADC oversamples the received signal. The demodulation circuit manipulates the sign of the samples to effectively multiply the received samples with one or more Walsh functions, and sums the resulting values over one symbol interval to determine the modulated amplitude of the corresponding functions.