A solid-state hydrophone may include a piezoelectric rod positioned between at least two electrodes. The piezoelectric rod may be disposed within a metallic housing to shield the piezoelectric rod and its connections from acoustic and electromagnetic waves. The piezoelectric rod and the electrodes may be potted in the mechanical housing using a potting material that may be positioned adjacent to the piezoelectric rod. At least a layer of the potting material may be positioned between the piezoelectric rod and the metallic housing to physically separate the piezoelectric rod from the metallic housing.

This disclosure is related to hydrophones, for example hydrophones that may be used in marine seismic surveying, permanent reservoir monitoring, downhole acoustic monitoring in a wellbore, and/or various other applications. Some embodiments of a hydrophone according to this disclosure are constructed such that a longitudinal stiffness of the hydrophone is greater than a circumferential stiffness of the hydrophone. In some embodiments, however, the longitudinal stiffness may be somewhat less than the circumferential stiffness. For example, the longitudinal stiffness may be greater than one half the circumferential stiffness in some cases.

An extremely low frequency hydrophone includes a housing forming an interior space comprising a backchamber. The housing includes an opening to the interior space, and a side of the housing comprises a diaphragm plate. A backplate is disposed inside the housing adjacent the diaphragm plate, and an electronics unit including a preamplifier is disposed in the interior space. The hydrophone further includes dielectric liquid substantially filling the interior space. A passageway permits inert gas to be introduced into the dielectric liquid in the interior space of the housing.

A fibre-optic hydrophone comprising a substantially incompressible tubular body, the tubular body generally having a geometry of a cylindrical shell defining an axis, and a deflectable outer wall, arranged to surround the tubular body in a distance thereof, and defining an axis that is arranged to substantially coincide with the axis of the tubular body. The hydrophone further comprising an optical fibre coil arranged on an outer surface of the outer wall, and a first and a second end lid arranged to seal the tubular body and the outer wall at a first end and a second end thereof, respectively, the first end lid and the second end lid being substantially incompressible. Additionally, the hydrophone comprising an outer cavity defined by an inner surface of the outer wall, an outer surface of the tubular body, the first lid, and the second lid; and an inner cavity defined by an inner surface of the tubular body, the first lid, and the second lid. The outer cavity is in fluid communication with the inner cavity via one or more passages in the tubular body, the outer cavity and the inner cavity being filled with a fluid, wherein the passages are configured to contribute to a function as a filter defining a low pass filter response with high cut-off frequency. In some embodiments the deflectable outer wall is cylindrical.

A solid-state hydrophone may include a piezoelectric rod positioned between at least two electrodes. The piezoelectric rod may be disposed within a metallic housing to shield the piezoelectric rod and its connections from acoustic and electromagnetic waves. The piezoelectric rod and the electrodes may be potted in the mechanical housing using a potting material that may be positioned adjacent to the piezoelectric rod. At least a layer of the potting material may be positioned between the piezoelectric rod and the metallic housing to physically separate the piezoelectric rod from the metallic housing.

An extremely low frequency hydrophone includes a housing forming an interior space comprising a backchamber. The housing includes an opening to the interior space, and a side of the housing comprises a diaphragm plate. A backplate is disposed inside the housing adjacent the diaphragm plate, and an electronics unit including a preamplifier is disposed in the interior space. The hydrophone further includes dielectric liquid substantially filling the interior space. A passageway permits inert gas to be introduced into the dielectric liquid in the interior space of the housing.

An improved hydrophone is presented that has extremely low acceleration sensitivity, hermetic sealing, and is self-shielded. The hydrophone can also contain an integral amplifier and pressure/depth limiting switch. The hydrophone is also designed such that it can use a single standard piezoelectric sensing element in many hydrophone designs that have different acoustic pressure sensitivities but the same capacitance. Lastly, the sensor is also designed to be low cost in high volumes using standard accelerometer manufacturing techniques. A hydrophone is also designed such that it can use a single standard piezoelectric sensing element that can be incorporated into several hydrophone configurations with varying acoustic pressure sensitivities. The sensor is also designed to be low cost in high volumes.

The invention relates to a hydrophone housing. The housing comprises an outer casing with an exterior shape being in close contact with sediment when buried therein and having a deflectable wall part. Solid material partly fills the casing to define an outer chamber behind the deflectable wall part, a cavity shaped so that an inner chamber is defined immediately surrounding a hydrophone sensing element held therein, and a first duct for liquid flow communication between the outer chamber and the cavity or an internal volume of the hydrophone sensing element. Thereby, a hydraulic coupling is provided so that an acoustic pressure causing small radial displacements of outer surface of the housing will, via liquid in the first duct, cause large radial displacements of the hydrophone sensitive element. The area of the deflectable wall part is much larger than the area of the sensitive element so that only small displacements of the housing are required to cause large displacements at the hydrophone sensing element.

Provided is a swim bladder bionic amphibious optical fiber ocean acoustic sensor, belonging to the field of optical fiber ocean sensors, consisting of a sound sensitive diaphragm, a diaphragm supporting shell, a section of coated optical fiber, a single-hole optical fiber sleeve and a single-mode optical fiber. An upper surface of the supporting shell is provided with two symmetrical overflow holes, and a structure includes a back cavity communicated with the overflow holes. A medium in the back cavity of the sensor may be replaced by inflating, deflating and filling water through the overflow holes, to achieve impedance matching with external environments. When the back cavity is inflated, the sensor serves as a fiber-optic microphone, and when the back cavity is deflated and filled with water, the sensor serves as a fiber-optic hydrophone. The working states could be switched flexibly to achieve a working mode like a swim bladder.

Computing device, software and method for balancing forces acting on a piston of a marine vibrator towed in a body of water. The method includes estimating with a management system located on a vessel or a controller located on a marine vibrator, a transient pressure disturbance in the body of water; computing, at the controller, a force correction for the piston of the marine vibrator, based on the transient pressure disturbance; and instructing an actuation system of the marine vibrator to apply the force correction to the piston in anticipation of an arrival of the transient pressure disturbance.