Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Directional detectors provide a signal channel with reduced noise content and improved noise channels with reduced signal content. Directional detectors may be magnetometers aligned with the magnetic field, or antennas aligned with the electric field, of signal or noise sources. Alignment may be performed by beam steering of the outputs of a three-channel detector, which may detect both signal and noise.

Abstract: Methods and systems employing combined source-channel coding for multi-carrier modulation (MCM). In some embodiments, a described method comprises: estimating channel gain to noise ratio (CGNR) as a function of frequency bin; determining MCM parameters that minimize distortion of one or more telemetry signals; generating a communications signal using the MCM parameters, and transmitting the communications signal via a communications channel. The MCM parameters may be determined by minimizing a telemetry signal distortion measure subject to CGNR and a transmit power constraint. The MCM parameters may further account for differing fidelity requirements when multiple telemetry signals are being transmitted.

Abstract: An acoustic attenuator includes a housing having an inner side surface which defines an interior chamber and at least one dampening member both physically and acoustically coupled to the housing and projecting into the interior chamber. Acoustic energy propagating within the housing is deflected into the dampening members for acoustically dispersal within the interior chamber. In various aspects thereof, the dampening members may include one or a group of two or more generally cylindrical sleeves having one end both physically and acoustically coupled to the housing and a second end projecting into the interior chamber. Preferably, when a group of two or more cylindrical sleeves are employed, the sleeves are nested within one another. The dampening members may further include a second, oppositely disposed, group of two or more acoustic attenuators nested within one another and interdigitated with the first group of cylindrical sleeves.

Abstract: Methods and systems for transmitting and receiving a discrete multi-tone (DMT) modulated signal in a fluid. Some illustrative embodiments may be a method comprising transforming an input data series into an information-carrying signal (the information-carrying signal carrying input data from the input data series as modulations of at least one of a plurality of evenly spaced frequency bins), and applying the information-carrying signal to a transducer that converts the information-carrying signal into pressure variations within a fluid.

Abstract: A communications system employing discrete multi-tone (“DMT”) modulated signals on a communications channel formed by inductively-coupled pipe. In one embodiment, the communications system includes a string of wired pipe joints that couple a transmitter to a receiver. Each pipe joint in the string possesses threaded ends configured for mechanically connecting with other pipe joints, a electrical or inductive coupler at each threaded end, and an insulated conductor that electrically connects the couplers. The transmitter and receiver communicate via DMT modulated signals transported by the wired pipe string. The system may further include multiple repeaters in the string. Each repeater may be configured to receive a DMT-modulated signal, to recover information from the DMT-modulated signal, and to re-transmit the information in the form of a DMT-modulated signal.

Abstract: Acoustic telemetry devices and methods that provide directional detection. In one embodiment, a disclosed acoustic telemetry device comprises at least two acoustic sensors and an electronics module. A first of the acoustic sensors detects a communication signal that propagates along a tubing string in a first direction. A second of the acoustic sensors is configured to detect the communication signal before the first acoustic sensor. The electronics module combines the detection signals from the acoustic sensors to obtain a combined signal that substantially excludes signals propagating in a direction opposite to the communication signal. Such signal suppression may significantly enhance the communication signal's signal-to-noise ratio, thereby increasing channel capacity. The acoustic telemetry device may be configured to support logging while drilling and/or full-duplex communication.

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 drill pipe forms an acoustic transmission channel for data to be transmitted from a downhole transceiver to a surface transceiver. By positioning a first low frequency acoustic attenuator between a drill bit and the downhole transceiver, acoustic noise generated by the drill bit is attenuated. Similarly, by positioning the surface transceiver between the top of the drill pipe and a second low frequency acoustic attenuator, acoustic noise generated by surface equipment is attenuated. In this manner, the first and second low frequency acoustic attenuators serve as terminators for the acoustic transmission channel.

Abstract: A downhole telemetry system employing code division multiple access (CDMA) is disclosed. In one embodiment, the downhole telemetry system comprises one or more downhole transmitters and an uphole receiver. Each of the downhole transmitters transmits a corresponding uplink signal which is generated using amplitude modulation of corresponding code word signals. The code word signals are orthogonal to each other, and the transmitters may be configured to adjust the timing to assure synchronous arrival of the various uplink signals at the receiver. Each of the transmitters may be allocated a different number of code words when it is desired to allow for unequal bandwidth requirements. Such allocation is preferably dynamic. Additional modulation techniques may be employed with CDMA, including frequency division multiplexing, time division multiplexing, and frequency re-use.

Abstract: A very high data rate telemetry system is provided for use in a wellbore. In a described embodiment, a telemetry system includes multiple nodes positioned in the wellbore and distributed over a substantial length of the wellbore. The nodes simultaneously communicate with a remote location at a very high combined data transmission rate. A method of communicating data in a wellbore is also provided. The method includes the steps of installing multiple modems in the wellbore, installing a remote modem at a location remote from the downhole modems, and simultaneously communicating data from each of the downhole modems to the remote location. Each downhole modem communicates with the remote modem using a unique set of frequency subchannels.

Abstract: A portion of at least one fiber is moved from a wellbore into a formation such that the portion is placed to conduct a signal responsive to at least one parameter in the formation. One particular implementation uses fiber optic cable with a process selected from the group consisting of a fracturing process, an acidizing process, and a conformance process.

Abstract: The present disclosure provides several methods for selecting and transmitting information from downhole using more than one channel of communication wherein data streams transmitted up each communications channel are each independently interpretable without reference to data provided up the other of the communications channels. Preferred embodiments incorporate the use of a combination of at least two of mud-based telemetry, tubular-based telemetry, and electromagnetic telemetry to achieve improved results and take advantage of opportunities presented by the differences between the different channels of communication.

Abstract: System, apparatus, and method of telemetering downhole sensor information to the surface while operations are performed in an oil or gas well using coiled tubing. Data are transmitted on coiled tubing as digital signals encoded in acoustic signals. In one implementation, a stripper packer through which coiled tubing is moved into a well is operated between at least a first state and a second state; and an acoustic communication device responds to operation of the stripper packer such that when the stripper packer is in the first state, the acoustic communication device is decoupled from acoustic communication with the coiled tubing, but when the stripper packer is in the second state, the acoustic communication device is coupled for acoustic communication with the coiled tubing.

Abstract: A portion of at least one fiber is moved into an exterior annulus of a well between a tubular structure in the well and the wall of the borehole of the well such that the portion is placed to conduct a signal responsive to at least one parameter in the exterior annulus. One particular implementation uses fiber optic cable with a cementing process whereby flowing cementing fluid pulls the portion of the cable into the exterior annulus.

Abstract: A synchronous CDMA telemetry system is provided for use in a wellbore. In one described embodiment, each data bit of digital outputs of multiple downhole data sources is multiplied by an orthogonal code unique to each data source. The resulting encoded outputs are modulated on a carrier frequency and summed on a transmission channel. The resulting signal is demodulated at a remote location and separately multiplied by each of the codes to separate out the contributions to the signal from each data source. The individual demodulated and decoded outputs are then integrated over the length of each data bit.

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: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Multiple noise channels are coupled to series connected adaptive filters for removing each noise source from the signal channel. The order of noise removal is selected to remove the most significant first.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Improved sensors provide noise channels with reduced signal content. Motion sensors are used to detect noise and provide a noise channel free of signal content. The motion sensors are shielded from electromagnetic signals to prevent detection of the telemetry signal.

Abstract: A method and a downhole telemetry system using discrete multitone modulation and adaptive filtering. The downhole telemetry system includes a downhole transmitter, a cable, and a surface receiver coupled to the downhole transmitter via the cable. The surface receiver adaptively filters noise from a signal received from the downhole transmitter. The method includes receiving a time-domain signal carrying desired information at specific frequencies and adaptively filtering at least a portion of the noise from the time-domain signal. The time-domain signal includes noise. The method may also include delaying the time-domain signal by a delay time to form a delayed time-domain signal, and adaptively filtering at least a portion of the periodic noise from the time-domain signal using the delayed time-domain signal.

Abstract: A communication system usable in a borehole in which a downhole modem wirelessly communicates with a surface modem using discrete multi-tone (“DMT”) modulation. The communication may be one-way (i.e., from downhole modem to surface modem, or vice versa) or two-way between the two modems.