A coherent sound source is provided for marine seismic surveys. An underwater sound projector for producing time-harmonic waveforms comprises two pistons positioned on either side of an electro-magnetic force generator substantially having mechanical and magnetic symmetry about its geometric center thereby creating a virtual node to substantially cancel reaction loads that occur when the pistons are actuated. The underwater sound projector optionally also includes control systems to improve the fidelity of the force generator, provide pressure compensation to the pistons, finely adjust the static position of the pistons, and change the depth and roll when it is configured as tow body. A plurality of underwater sound projectors can be configured in an array. A load-bearing umbilical can connect the underwater sound projectors to a ship, transmit electrical power to each array element and serve as a duplex data transmission medium to route commands from the ship to the projector and report machinery status to the ship.

Provided is a sensor for measuring water levels of groundwater and surface water using magnetostriction displacement and multi measurement system for groundwater and surface water by using the same. The sensor includes an outer case having a hollow space therein and extending in a longitudinal direction, a magnetostriction line spaced apart from an inner wall in the hollow space of the outer case to extend in the longitudinal direction, a floating permanent magnet guided along the magnetostriction line to be movable in the longitudinal direction, the floating permanent magnet being changed in position to correspond to a water level; and a transceiver applying a current pulse into the magnetostriction line to receive an elastic wave that is generated while first magnetic fields formed in a circumferential direction of the magnetostriction line by the current pulse crosses a second magnetic fields formed in an axial direction of the magnetostriction line by the permanent magnet.

Embodiments relate to marine acoustic vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine acoustic vibratory may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a spring element coupled to the piston plate and the fixture; and a driver coupled to the piston plate and the fixture and configured to move the piston plate back and forth.

Marine vibrators and methods of use are disclosed. A marine vibrator may comprise a containment housing, where the containment housing comprises a marine vibrator internal volume, wherein the marine vibrator internal volume comprises a first gas at a first gas pressure. The marine vibrator may further comprise a sound radiating surface. The marine vibrator may additionally comprise a compliance chamber in contact with the first gas, wherein the compliance chamber comprises a chamber housing and a moveable structure, wherein at least the chamber housing and the moveable structure form a compliance chamber internal volume which holds a second gas at a second gas pressure, wherein the moveable structure is configured to move in response to a change in the first gas pressure, and wherein the compliance chamber is configured to condense the second gas in response to compression of the marine vibrator internal volume by the moveable structure.

This disclosure is related to marine seismic sources, for example marine seismic sources known in the art as benders. Some embodiments of this disclosure use magnetic reluctance forces to produce seismic energy. For example, pole pieces may be attached to one or more plates of a marine seismic source, and a wire coil may induce an attractive force between the pole pieces to cause deformation of the plates to produce seismic energy. Such marine seismic sources may be components of a marine seismic survey system, and may be used in a method of marine seismic surveying. Methods of making marine seismic sources are also disclosed.

The present disclosure includes a method for monitoring a subsurface formation including disposing an antenna in a horizontal wellbore, the antenna including a plurality of piezoelectric modules. A voltage signal is applied to at least one of the piezoelectric modules to cause the at least one piezoelectric modules to emit seismic energy into the subsurface formation. A resulting signal is received at a receiver. A property of the subsurface formation is determined based, at least in part, on the resulting signal.

Embodiments related to a sound source that comprises a base plate configured to bend and generate acoustic energy; a spring coupled to the base plate; and a mass element coupled to the spring, wherein the sound source is operable to produce at least two resonance frequencies in the sound source.

A coherent sound source is provided for marine seismic surveys. An exemplary underwater sound projector comprises a plurality of pistons actuated by an electromagnetic force generator having components comprising a stator, armatures, electrical coils, and permanent magnets. The pistons and the components are arranged to create mechanical and magnetic symmetry about a geometric center of the projector to reduce reaction loads that occur when the pistons are actuated. The stator and the armatures have magnetic poles that employ a tapered geometry. The projector optionally includes control systems to improve the fidelity of the force generator, provide pressure compensation to the pistons, finely adjust the static position of the pistons, and/or change the depth and roll when the projector is configured as a tow body. A plurality of such projectors can be configured in an array. An umbilical can connect the projectors to a vessel, transmit electrical power and compressed gas to each array element and/or provide a data transmission medium between the projector and the vessel.

A piezoelectric transducer is mounted in a housing. An impedance matching layer is provided between the piezoelectric transducer and the housing. The impedance matching layer includes high-permittivity regions that have a first permittivity, and low-permittivity regions that separate the high-permittivity regions and have a second permittivity. The second permittivity is lower than the first permittivity.

A downhole ultrasonic transducer (10) used to transmit and/or receive ultrasonic waves in a hydrocarbon well where a fluid is present comprises: a metal housing (11) defining an internal cavity (12) isolated from the fluid of the hydrocarbon well (100) by a membrane wall (13) made of metal or metal alloy; a piezoelectric element (14) mounted inside the internal cavity (12), the piezoelectric element (14) having a front side (20) mechanically coupled on the membrane wall (13);

wherein: the internal cavity (12) is at a pressure unrelated to a hydrocarbon well pressure; a back side (21) of the piezoelectric element (14) is arranged to be free to oscillate in the internal cavity (12) so as to generate a high acoustic impedance mismatch between the piezoelectric element (14) and the internal cavity (12) at the back side (21) and to maximize acoustic transmission at the front side (20); and a thickness (ei) of the membrane wall (13) is such that there is a common resonance between the membrane wall and the piezoelectric element thereby achieving high acoustic transmission through the membrane wall (13), and such that the membrane wall (13) is suitable to resist to the hydrocarbon well pressure.