An immersible ultrasonic transmitter consists of an end element of a first type, an end element of a second type and at least one transmitting member. The end element of the first type comprises a first cylindrical transmitter, a stack of piezoelectric elements, a second cylindrical transmitter and a coupling element with a threaded connection for coupling together the two cylindrical transmitters. The transmitting member contains a stack of piezoelectric elements, a cylindrical transmitter of a transmitting member, and an element with a threaded connection for coupling together the cylindrical transmitter of a transmitting member and the cylindrical transmitter of an adjacent transmitting member, or the second cylindrical transmitter of the end element of the first type. The end element of the second type comprises a first cylindrical transmitter, a stack of piezoelectric elements and a coupling element with a threaded connection for coupling together the cylindrical transmitter and the cylindrical transmitter of an adjacent transmitting member.

An apparatus for detecting a location of an optical fiber having an acoustic sensor disposed subsurface to the earth includes an acoustic emitter configured to emit a first signal having a first frequency and a second signal having a second frequency that is higher than the first frequency, the first and second emitted acoustic signals being azimuthally rotated around the borehole and an optical interrogator configured to interrogate the optical fiber to receive an acoustic measurement that provides a corresponding first received signal and a corresponding second received signal. The apparatus also includes a processor configured to (i) frequency-multiply the first received signal to provide a third signal having a third frequency within a selected range of the second frequency, (ii) estimate a phase difference between the second received signal and the third signal, and (iii) correlate the phase difference to the location of the optical fiber.

Embodiments relate to relate to marine vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine vibrator may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and the fixture; a driver disposed in the marine vibrator, wherein the driver is coupled to the piston plate and the fixture; and a container coupled to the piston plate, wherein the container is configured to hold a variable mass load; wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable mass load.

A reaction mass seismic survey source that is located in an underground casing. The seismic source includes a non-planar base plate; a reaction mass located on the non-planar base plate; and a flextensional element housed in a recess of the reaction mass and configured to vibrate the non-planar base plate when actuated, to generate seismic waves underground.

Apparatus and techniques are disclosed relating to a two-axis sensing element. In various embodiments, a two-axis sensing element includes a mounting plate that includes a first pair of mounting slots oriented in a first direction and a second pair of mounting slots oriented in a second, different direction. Further, in various embodiments, the two-axis sensing element may include a first pair of bender elements and a second pair of bender elements. The first pair of bender elements may be mounted through the first pair of mounting slots such that the first pair of bender elements is oriented in the first direction and the second pair of bender elements may be mounted through the second pair of mounting slots such that the second pair of bender elements is oriented in the second, different direction. In various embodiments, the mounting plate may transect each of the bender elements into two cantilever portions.

Apparatus and techniques are disclosed relating to sensor housing and spacer carrier assemblies. In various embodiments, a spacer carrier provides a cavity through a body of the spacer carrier and a first alignment element positioned at a first end of the cavity. In some embodiments, a sensor housing is configured to be deployed within the cavity through the body of the spacer carrier. The sensor housing may include a housing body configured to receive a sensor and a second alignment element configured to interface with the first alignment element. In various embodiments, the first and second alignment elements are configured to maintain an orientation of the sensor housing within the cavity when the sensor housing is inserted into the spacer carrier.

A frequency-shifting system and method for cement-bond-logging tools is disclosed. Shifting the frequency of a received acoustic signal to a lower signal for transmission on a wireline is accomplished by digitizing the received signal at a first sampling rate, storing the digitized data in memory, and converting the digitized data to an analog signal at a second sampling rate. The digitizing sampling rate is higher than the conversion sampling rate. This allows an acoustic operating frequency that is greater than the wireline transmission frequency, and therefore allow signal-to-noise optimization not available in conventional systems. Acoustic transducers can be operated at higher frequencies than what is acceptable for wireline transmission. This allows for the use of transducers not conventionally used in the art (such as piezoelectric stacks).

The method for enhanced depth penetration of energy into a formation may include mechanically stimulating the formation at a first frequency to induce mechanical stress in the formation and directing electromagnetic radiation towards the formation while mechanically stimulating the formation.

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.

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.