An outer tubular is imaged by a pad assembly disposed within an inner tubular inserted within the outer tubular. The pad assembly is in contact with the inner tubular, and includes an acoustic pressure source, a backing mounted to a side of the acoustic pressure source, and an intervening layer between the acoustic pressure source and inner tubular. Signals generated by the pad assembly propagate radially outward from the inner tubular and reflect from the outer tubular. The generated and reflected signals travel through a medium between the inner and outer tubulars. An estimate of the distance between the inner and outer tubulars is based on the time from generation of the signal to when the reflected signal is sensed. The pad assembly and its components are during its design.

The invention relates to a transmitter of a through bit dipole acoustic logging device and the logging device, and the transmitter includes a substrate and 2 piezoelectric ceramic plates respectively at either sides of the substrate; wherein the piezoelectric ceramic plate is composed of at least one block of piezoelectric ceramic units; wherein the lengthwise direction of the piezoelectric ceramic elements is along the width direction of the piezoelectric ceramic plates, the width direction of the piezoelectric ceramic units is along the thickness direction of the piezoelectric ceramic plates, and the thickness direction of the piezoelectric ceramic units is along the lengthwise direction of the piezoelectric ceramic plates; the polarization directions of the piezoelectric ceramic units are along the thickness direction of the piezoelectric ceramic units; when electric excitation is applied along the length of the piezoelectric ceramic plate, the piezoelectric ceramic plate on one side of the substrate is extended while the piezoelectric ceramic plate of the other side shortened, pushing the substrate to form a bending vibration, transmitting the thrust to the media and generating acoustic waves.

Embodiments relate to the restriction of gas flow in a piston-type marine vibrator to compensate for air-spring effects. An embodiment provides marine vibrator comprising: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and to the fixture; a driver coupled to the piston plate and to the fixture; and a variable gas flow restrictor disposed in an interior volume of the marine vibrator, wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable gas flow restrictor.

Disclosed are devices and methods for marine geophysical surveying. An example device may comprise a shell, a base plate, wherein the base plate is coupled to the shell, a driver disposed within the shell, an inner spring element disposed within the shell, wherein the inner spring element is coupled to the driver, wherein outer ends of the inner spring element are coupled to outer ends of the inner spring element at spring element junctions, an outer spring element disposed within the shell, wherein outer ends of the outer spring element are coupled to the spring element junctions, and a back mass disposed on the outer spring element.

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.

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.

Systems and methods of the present disclosure relate to signal attenuation for acoustic logging tools. An acoustic logging tool includes acoustic transducers. Each acoustic transducer includes a body, a piezoelectric element disposed on a first end of the body to receive or transmit at least one signal, and a wedge-cut disposed on an opposite end of the body. The wedge-cut defines a sloped portion operable to attenuate signals.

A dual frequency ultrasonic and sonic actuator with constrained impact mass is presented. According to one aspect, displacement of the impact mass is constrained by cavity to which ultrasonic stress from the tip of a horn is applied. According to another aspect, the displacement of the impact mass is constrained by a spring attached to the tip of the horn. According to another aspect, the displacement of the impact mass is constrained by a flexure. The constrained impact mass converts the ultrasonic stress to lower frequency sonic stress that is coupled to a transmitting element for transmission through a surface. According to one aspect, the transmitting element is a longitudinal probe. According to another aspect, the transmitting element is a drill bit used to penetrate though the surface. According to another aspect, the transmitting element is a thumper used to transmit elastic waves though the surface.

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.

Systems, devices, and methods for estimating a value of a parameter of interest of an earth formation intersected by a borehole. Methods include conveying a carrier in the borehole having disposed thereon an acoustic imaging tool including at least one convex linear phased array module, each of the at least one module comprising a rigid shell forming a compartment containing a piezoelectric component array; using the acoustic imaging tool to take acoustic measurements of the borehole; and using the acoustic measurements to estimate at least one parameter of interest. Each module may be self-contained. The tool may include a plurality of modules circumferentially arrayed about a portion of the acoustic tool. Methods include individually removing one selected module from the acoustic tool. Methods may include selecting an outer tool diameter the same as an inner borehole diameter borehole and selecting a maximum number of modules fitting the outer tool diameter.