A downhole imaging system comprises an imaging device operably coupled to a drill string and configured to generate an image of a subterranean formation from within a wellbore. The downhole imaging system comprises a processor operably coupled to the imaging device. The imaging device includes a sensor comprising a transmitter and a receiver, and a coding mask located between the sensor and the subterranean formation. Downhole assemblies including such devices and methods of generating an image of a subterranean formation in a wellbore are also disclosed.

An acoustic logging tool may comprise a center load carrying pipe, a receiver module connected to the center load carrying pipe, one or more transmitter modules connected to the center load carrying pipe, and one or more mass modules connected to the center load carrying pipe.

A method and systems for performing a borehole operation with a borehole fluid that includes applying an amplitude oscillation deformation force to a sample of the borehole fluid over a period of time, measuring the deformation force from the sample, determining a storage modulus of the borehole fluid over the period of time based on the measured deformation force, determining a gel strength of the borehole fluid by correlation with the storage modulus, comparing the gel strength with a desired gel strength and if the gel strength is outside of an acceptable range of the desired gel strength, adjusting a drilling parameter, a composition of the borehole fluid, or a combination thereof, and using the borehole fluid in the borehole operation. Determining the storage modulus and the gel strength may be done using a processor and the force may be applied using a piezoelectric device.

An acoustic transducer is provided. The acoustic transducer includes a housing, a backing, a piezocomposite element adjacent the backing within the housing, and a diaphragm covering on an outward facing surface of the piezocomposite element.

A transducer, method, and downhole tool for acoustic logging. The acoustic transducer comprises a piezoelectric material comprising a body and grooves formed on the body. The grooves comprise a first groove that intersects with a second groove on the body. The method of acoustic logging a wall comprises transmitting an acoustic pulse at the wall using the acoustic transducer. The method also comprises generating a signal indicative of a reflection of the pulse using the acoustic transducer; and determining an acoustic parameter based on the signal using a processor. The acoustic logging tool is locatable in a wellbore intersecting a subterranean earth formation. The acoustic logging tool comprises the acoustic transducer and a processor configured to determine an acoustic parameter based on a signal generated by the acoustic transducer, the signal being indicative of the acoustic wave.

A marine sensor system includes an enclosure that defines an interior volume. The enclosure is configured to be immersed in water. A sensor having a positive output node and a negative output node is disposed within the interior volume of the enclosure. A first parasitic capacitance between the positive output node and the enclosure is substantially equal to a second parasitic capacitance between the negative output node and the enclosure. A cross feed signal that is propagated through a path in water outside the enclosure is coupled to the output nodes in a balanced manner, which enables a differential amplifier to reject the cross feed noise.

An underwater acoustic source can include a first piston coupled to a second piston and a plurality of linear magnetic actuators directly connected to each of the first piston and the second piston. Each of the plurality of linear magnetic actuators include a linear shaft positioned within the cylindrical magnetic assembly and mounted to the first end of the rigid ferromagnetic housing and the second end of the rigid ferromagnetic housing, such that the linear shaft is stationary, and linear bearings positioned between the cylindrical magnet assembly and the linear shaft to allow the cylindrical magnet assembly to translate along the linear shaft relative to the cylindrical electrical coil, and wherein each of the plurality of linear magnetic actuators is activated, the first piston and the second piston oscillate towards and away from each other, causing acoustic waves to be generated in water.

The disclosed embodiments include quadrupole transmitters and methods to determine wave velocities of a downhole formation. In some embodiments, the quadrupole transmitter has a first piezoelectric ring and a second piezoelectric ring that alternatively contracts and expands in opposite radial directions relative to the first piezoelectric ring in response to being simultaneously excited with the first piezoelectric ring. The quadrupole transmitter also includes a covering sleeve surrounding exterior surfaces of the two piezoelectric rings. The quadrupole transmitter further includes a windowed sleeve surrounding the two piezoelectric rings and having a first portion and a second portion adjacent to the first portion. The first portion and the second portion are formed from multiple window sections and adjacent covered sections that are positioned around different sections of the piezoelectric rings to allow transmission of quadrupole acoustic signals when the piezoelectric rings are simultaneously excited.

An ultrasonic transducer may comprise a transducer body including a first face and a second face disposed on opposite sides of the transducer body, wherein the transducer body comprises a piezoelectric material; a first transducer edge disposed on the transducer body; and a second transducer edge disposed on the transducer body, wherein the first edge is disposed on the transducer body substantially opposite from the second edge, and wherein the first and second transducer edges intersect a perimeter of the transducer body, and wherein the first and second edge forms an angle no less than 3 degrees.

An underwater acoustic transducer that is capable of radiating acoustic energy at low frequencies. A transducer which is a resonant low frequency bender-type transducer driven at its end supports by a piezoelectric stack of material operating with inner and outer parts driven in opposite directions creating a bending motion of a radiating beam, plate or disc. The small piezoelectric motions at the beam supports are magnified by the leveraged motion of the bending beam(s) creating significant output at low frequencies.