Abstract: A method of identifying a material and/or condition of a material in a borehole is described, together with related apparatus. The material may either be between first and second tubulars or between a first tubular and a wall of the borehole. The method may include providing a reference quality factor (Qreference) for one or more known materials in one or more known conditions and measuring a downhole quality factor (Qmeasured) of the material and/or material condition to be identified. A spectral ratio ?=(Qmeasured/Qreference) may then be computed for one or more known materials under one or more known conditions followed by an analysis of the spectral ratios to identify the material and/or condition of the material in the borehole.

Abstract: A spacecraft including a frame including a joint coupling a first frame portion to a second frame portion, and an acoustic communication system configured to transfer acoustic data signals across the joint between the first frame portion and the second frame portion.

Abstract: A communication system that is positionable in a wellbore can include a first transceiver positioned externally to a casing string. The first transceiver can be operable to detect a presence or an absence of a surface wave; determine a location of a fluid in the wellbore based on the presence or the absence of the surface wave; and transmit data indicative of the location to a second transceiver. The surface wave can include an electromagnetic wave that has a magnetic field or an electric field that is non-transverse to a direction of propagation of the surface wave. The communication system can also include the second transceiver, which can be positioned externally the casing string and operable to receive the data.

Abstract: Systems and methods of performing a seismic survey in a marine environment are provided. The system includes a seismic data acquisition unit disposed on a seabed in the marine environment. The seismic data acquisition unit includes a local pressure sensor, an optical transmitter and an optical receiver to determine one or more pressure values. The system includes an extraction vehicle including a reference pressure sensor, an optical transmitter, and an optical receiver to establish an optical communications link with the seismic data acquisition unit, and generate reference pressure data. The system includes at least one of the local pressure sensor and the one or more pressure values calibrated based on the reference pressure data generated by the extraction vehicle.

Abstract: A transducer assembly including a rigid transducer housing. The transducer housing has an interior space and defines a transducer socket and a pressure balancing cylinder. A transducer device is fixedly mounted within the transducer socket. A pressure balancing piston is reciprocably mounted within the pressure balancing cylinder. A pressure balancing fluid and an electronics assembly are contained within the interior space. The electronics assembly is operatively connected with the transducer device. A measurement tool including a tool body and one or more transducer assemblies. The tool body defines one or more pressure balancing body passages extending between mounting pockets in the tool body. The transducer housings define one or more pressure balancing housing passages extending between the interior space and the exterior of the transducer housings. At least some pressure balancing body passages and some pressure balancing housing passages are in pressure communication with each other.

Abstract: The present disclosure provides methods of data acquisition and processing of seismic data that combines nodal survey design, especially sparse nodal surveys, with the hybrid gather processing methodologies.

Abstract: The transmission system combines a self-contained, wireless seismic acquisition unit and a wireless, line of site, communications unit to form a plurality of individual short-range transmission networks and also a mid-range, line of sight transmission network. Each seismic unit has a power source, a short-range transmitter/receiver disposed within a casing and a geophone disposed within the casing. Each wireless communications unit is formed of an elongated support structure on which is mounted an independent power source, mid-range radio transmitter/receiver; and a short-range transmitter/receiver configured to wirelessly communicate with the short-range transmitter/receiver of the acquisition unit. Preferably, when deployed, the acquisition unit is buried under the surface of the ground, while the wireless communications unit is positioned in the near vicinity of the buried unit so as to vertically protrude above the ground.

Abstract: A system for self-tuning sonic transmitters which transmits a plurality of frequencies into a downhole formation, then identifies which of the transmitted frequencies generates the best response from the formation. The system then uses the best frequency identified for subsequent logging of formation data until a subsequent tuning sequence is initiated.

Abstract: Embodiments, including apparatuses, systems, and methods, for attaching autonomous seismic nodes directly to a deployment cable. The nodes may be attached to the deployment cable by a removable fastener or insert. The fastener may be a staple that surrounds the cable and rigidly couples to the node to securely fasten the cable to the node. The fastener may be secured into the node itself, a housing or enclosure surrounding the node, or into a receiver or mechanism attached to the node. Other fasteners besides a staple may include bands, wires, pins, straps, ties, clamps, and other similar devices that may be inserted around a portion of the deployment line and be removably coupled to the node. After retrieval of the node, the fastener may be removed and discarded.

Abstract: Methods of designing seismic survey and acquisition of seismic data with reduced noise using equally or optimally irregularly spaced sources or receivers are described. Specifically, prime number ratios for the station to line spacing is used to prevent harmonic leakage and other noise contaminations in the acquired seismic data.

Abstract: Systems and methods for underwater communication using a MIMO acoustic channel. An acoustic receiver may receive a signal comprising information encoded in at least one transmitted symbol. Using a two-layer iterative process, the at least one transmitted symbol is estimated. The first layer of the two-layer process uses iterative exchanges of soft-decisions between an adaptive turbo equalizer and a MAP decoder. The second layer of the two-layer process uses a data-reuse procedure that adapts an equalizer vector of both a feedforward filter and a serial interference cancellation filter of the adaptive turbo equalizer using a posteriori soft decisions of the at least one transmitted symbol. After a plurality of iterations, a hard decision of the bits encoded on the at least one transmitted symbol is output from the MAP decoder.

Abstract: The invention relates to a method for seismic survey by autonomous seismic nodes (1) at a sea floor (2), comprising: —attaching the seismic nodes (1) to a rope (3); —loading the rope (3) with the seismic nodes into a node deployer (4); —lowering the node deployer (4) into the sea (5); —towing the node deployer (4) above the sea floor (2); —deploying the rope (3) with the seismic nodes (1) at the sea floor (2); —collecting seismic data by the seismic nodes (1); —retrieving the rope (3) with the seismic nodes (1) from the sea floor (2), and —unloading seismic data from the seismic nodes (1). The invention also relates to a node deployer (4) for deploying a rope (3) with seismic nodes (1) at the sea floor (2), comprising a magazine (7) for the rope (3) with the seismic nodes (1).

Abstract: A low frequency ultrasonic communication system includes: a low frequency ultrasonic transmitting apparatus configured to transmit data using a low frequency ultrasonic wave; and a low frequency ultrasonic receiving apparatus configured to recover the data by processing a low frequency ultrasonic reception signal transmitted from the low frequency ultrasonic transmitting apparatus. In communication between the transmitting apparatus and the receiving apparatus, modulation is performed using a DPSK scheme, and FEC coding is used to perform channel coding before the modulation.

Abstract: A method of manufacturing a streamer section. The method includes coupling together a plurality of prefabricated harness modules. A harness module includes a plurality of geophysical sensors disposed along a length of the harness module and a sensor node communicatively coupled to the plurality of sensors. A first connector is disposed at a first end of the harness module and a second connector disposed at a second end of the harness module. The first connector is coupled to the sensor node and is configured to couple to a second harness module and receive data from a sensor node in the second harness module. The second connector is coupled to the sensor node and is configured to couple to a third harness module and forward data to a sensor node in the third harness module.

Abstract: A survey system including a multibeam echo sounder and a beam selector for selecting beams with the largest amplitudes.

Abstract: Methods and apparatus for performing formation evaluation in a borehole intersecting an earth formation. Methods may include exciting at a first borehole depth at least one critical refraction wave by steering an acoustic beam transmitted by at least one ultrasonic transmitter to an interface in the formation to intercept the interface at a critical angle; receiving an acoustic signal comprising critical refraction wave data at a logging tool in the borehole; and obtaining a wave property measurement from the critical refraction wave data. The interface may be the borehole wall in an open-hole well or behind casing. Methods include using ultrasonic transmitter(s) to generate the plurality of acoustic beams, identifying critical refraction wave data within the response signal corresponding to the at least one critical refraction wave, and obtaining the wave property measurement from the critical refraction wave data.

Abstract: The present disclosure provides systems and methods associated with mode conversion for ultrasound and acoustic radiation devices. A mode converting structure (holographic metamaterial) is formed with a distribution of acoustic material properties selected to convert an acoustic pressure pattern from a first mode to a second mode to attain a target radiation pattern that is different from the input radiation pattern. A solution to a holographic equation provides a sufficiently accurate approximation of a distribution of acoustic material properties to form a mode converting device. One or more optimization algorithms can be used to improve the efficiency of the mode conversion and generation of the acoustic mode converter.

Abstract: An ultrasonic sensor includes a two-dimensional array of ultrasonic transducers. A signal generator is configured to generate a plurality of transmit signals, wherein each transmit signal of the plurality of transmit signals has a different phase delay relative to other transmit signals of the plurality of transmit signals. A plurality of shift registers is configured to store a beamforming space including a beamforming pattern to apply to the two-dimensional array, wherein the beamforming pattern identifies a transmit signal of the plurality of transmit signals that is applied to each ultrasonic transducer of the beamforming space that is activated during a transmit operation. An array controller is configured to control activation of ultrasonic transducers during a transmit operation according to the beamforming pattern and configured to shift a position of the beamforming space within the plurality of shift registers such that the beamforming space moves within the two-dimensional array.

Abstract: A test for screening defects of a transmission/reception circuit in an IC is enabled at low cost, without withstand voltage violation, and without carrying out electrical contacts with many terminals connected to oscillators. In a transmission/reception separation switch circuit using transistors as switch elements, a potential of a gate is lowered in a test more than the potential in a case of reception to avoid gate-source withstand-voltage violation when a large-amplitude signal is input, and an internal-signal loopback test is carried out without destroying a reception circuit.

Abstract: A system for constraining a dither time can comprise a source and a controller coupled to the source. The controller can be configured to actuate the source in sequence, while the source is moving through a fluid volume at a bottom speed, with an actuation time interval between each actuation comprising a sum of a nominal time and a dither time for each actuation and constrain the dither time for each actuation such that a reduction of the actuation time interval relative to a directly precedent actuation time interval is at most a threshold dither time difference, wherein the threshold dither time difference corresponds to a maximum bottom speed.