Abstract: Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Abstract: Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Abstract: A disclosed data acquisition system includes one or more streamers having multiple spaced apart sensor units. At least one sensor unit includes at least one digital sensor employing a quantized feedback loop to produce a digital output signal. A data recording system collects and stores data from the sensor units. The quantized feedback loop may be adapted to exert a quantized force on the sensing element. A described method for acquiring data includes deploying at least one streamer having multiple spaced apart sensor units, where at least a portion of the sensor units include a digital sensor employing a quantized feedback loop to produce a digital output signal. A stimulus event is triggered. Data is received from the sensor units and stored.

Abstract: Geophysical sensor cables. At least some of the example embodiments are sensor cable sections including hydrophone groups defined along a geophysical sensor cable section, the hydrophone group may include: a substrate of flexible material having electrical traces thereon, the substrate within the internal volume or embedded within the outer jacket, and the substrate having has a length measured parallel to the longitudinal axis; and a plurality of hydrophones mechanically coupled to the substrate. The substrate may have a variety of shapes, including one or more strips, helix, double helix, and cylindrical.

Abstract: Techniques are disclosed relating to sensors configured to measure acceleration and pressure. In various embodiments, an apparatus includes a first hydrophone sensor having a first piezoelectric material and a first housing structure and a second hydrophone sensor having a second piezoelectric material and a second housing structure. In some embodiments, the apparatus includes a first pair of wires configured to provide a first differential voltage and a second pair of wires configured to provide a second differential voltage. The first pair of wires may be coupled to the first hydrophone sensor and the second pair of wires may be coupled to the second hydrophone sensor. In various embodiments, the apparatus is configured to determine, based on the first and second differential voltages, a pressure and an acceleration experienced by the first and second hydrophone sensors.

Abstract: Techniques are disclosed relating to calibrating sensors configured to measure both pressure and acceleration. In various embodiments, a system detects a first voltage produce by a first piezoelectric material in a hydrophone when the hydrophone is exposed to an acceleration and detects a second voltage produced by a second piezoelectric material in the hydrophone when the hydrophone is exposed to the acceleration. The system, in some embodiments, compares the first voltage and the second voltage. Based on the comparing of the first and second voltages, in some embodiments, the system determines a resistance for a variable resistor coupled to one of the first and second piezoelectric materials.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A modeling module is included and configured to calculate a reference potential at a selected electrode for each of the plurality of geophysical survey cables, as well as a calculation module to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to the reference potential.

Abstract: A merged particle velocity signal is generated by merging a recorded vertical particle velocity signal, scaled in an upper frequency range using a time-dependent arrival angle as determined by velocity analysis, with a simulated particle velocity signal, calculated in a lower frequency range from a recorded pressure signal using a time-varying filter based on the time-dependent arrival time. Combined pressure and vertical particle velocity signals are generated by combining the recorded pressure and merged velocity signals.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential.

Abstract: A disclosed pressure-responsive sensor includes a flexible element contained within an enclosure and a membrane configured to exert an electrostatic force on the flexible element to cause the flexible element to respond to pressure variations on the membrane. A disclosed pressure-sensing method includes electrostatically coupling a membrane to a flexible element contained within an enclosure to transfer a pressure response of the membrane to the flexible element. Motion of the flexible element is converted into a pressure signal.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A calculation module is included and configured to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to a reference potential assumed to be present at a selected electrode for each of the plurality of geophysical survey cables. Each reference potential is assumed to be of a magnitude that is within a tolerance range of a common reference potential.

Abstract: The present disclosure describes various geophysical survey systems and methods for mapping an electric potential field. At least one illustrative embodiment includes an electromagnetic (EM) source and geophysical survey cables that each includes multiple electrodes spaced apart along each geophysical survey cable's length, and multiple data acquisition units that each obtains measurements indicative of an electric potential between two the electrodes. A modeling module is included and configured to calculate a reference potential at a selected electrode for each of the plurality of geophysical survey cables, as well as a calculation module to combine signals representative of the measurements to produce signals indicative of the electric potential of each electrode relative to the reference potential.

Abstract: A disclosed pressure-responsive sensor includes a flexible element contained within an enclosure and a membrane configured to exert an electrostatic force on the flexible element to cause the flexible element to respond to pressure variations on the membrane. A disclosed pressure-sensing method includes electrostatically coupling a membrane to a flexible element contained within an enclosure to transfer a pressure response of the membrane to the flexible element. Motion of the flexible element is converted into a pressure signal.

Abstract: A disclosed digital sensor includes a pair of piezoelectric sensors that respond to acceleration and pressure in opposite ways, a pair of digital transducer circuits each employing a quantized feedback path to obtain digital sensor signals for the piezoelectric sensors, and a combiner circuit that combines the digital sensor signals to produce a compensated digital output signal. The compensated digital output signal may be a pressure compensated acceleration signal, an acceleration compensated pressure signal, or both. Also disclosed is a signal detection method that includes configuring a pair of piezoelectric membranes in a piezoelectric sensor to respond to acceleration and pressure in opposite ways, and based on their responses, producing at least one of a digital pressure compensated acceleration signal and a digital acceleration compensated pressure signal. The digital signals may be produced in part by applying a quantized feedback signal to at least one of the piezoelectric membranes.

Abstract: A disclosed data acquisition system includes one or more streamers having multiple spaced apart sensor units. At least one sensor unit includes at least one digital sensor employing a quantized feedback loop to produce a digital output signal. A data recording system collects and stores data from the sensor units. The quantized feedback loop may be adapted to exert a quantized force on the sensing element. A described method for acquiring data includes deploying at least one streamer having multiple spaced apart sensor units, where at least a portion of the sensor units include a digital sensor employing a quantized feedback loop to produce a digital output signal. A stimulus event is triggered. Data is received from the sensor units and stored.

Abstract: A merged particle velocity signal is generated by combining a recorded vertical particle velocity signal, scaled in an upper frequency range using a time-dependent arrival angle as determined by cross-ghosting analysis, with a simulated particle velocity signal, calculated in a lower frequency range from a recorded pressure signal using a time-varying filter based on the time-dependent arrival angle. Combined pressure and vertical particle velocity signals are generated from the recorded pressure and merged particle velocity signals.

Abstract: A time-dependent arrival angle is determined at a single receiver station in a towed streamer. Up-going and down-going pressure wavefields are calculated from pressure and vertical particle velocity wavefields measured at the receiver station. Extrapolated up-going and down-going pressure wavefields are generated from the up-going and down-going pressure wavefields displaced by a time delay based upon the time-dependent arrival angle.

Abstract: A time-dependent arrival angle is determined at a single receiver station in a towed streamer. Up-going and down-going pressure wavefields are calculated from pressure and vertical particle velocity wavefields measured at the receiver station. Extrapolated up-going and down-going pressure wavefields are generated from the up-going and down-going pressure wavefields displaced by a time delay based upon the time-dependent arrival angle.

Abstract: A merged particle velocity signal is generated by combining a recorded vertical particle velocity signal, scaled in an upper frequency range using a time-dependent arrival angle as determined by cross-ghosting analysis, with a simulated particle velocity signal, calculated in a lower frequency range from a recorded pressure signal using a time-varying filter based on the time-dependent arrival angle. Combined pressure and vertical particle velocity signals are generated from the recorded pressure and merged particle velocity signals.

Abstract: A merged particle velocity signal is generated by merging a recorded vertical particle velocity signal, scaled in an upper frequency range using a time-dependent arrival angle as determined by velocity analysis, with a simulated particle velocity signal, calculated in a lower frequency range from a recorded pressure signal using a time-varying filter based on the time-dependent arrival time. Combined pressure and vertical particle velocity signals are generated by combining the recorded pressure and merged velocity signals.