Abstract: In one aspect, the disclosure provides an apparatus that includes an acoustic transducer, and a backing coupled to the transducer, wherein the backing includes solid grains with fluid between the grains.

Abstract: A transducer assembly for downhole imaging includes a 1-3 Piezoelectric composite transducer of high Q ceramic rods in a polymer matrix. The assembly also includes a Teflon® window, a fluid-filled cavity adjacent to the window, and impedance matching material between the composite transducer and the fluid. The transducer is positioned to reduce the reverberation time.

Abstract: Systems, devices, and methods for evaluating an earth formation intersected by a borehole using signals produced at a plurality of borehole depths by an ultrasonic transducer in the borehole, the signals produced by the transducer including ringdown signals from the ultrasonic transducer and echo signals from a wall of the borehole from a plurality of azimuthal orientations.

Abstract: An apparatus for imaging a borehole wall includes an array of acoustic transducers and a controller. The controller scans a section of the borehole wall with first acoustic beams that are transmitted by a series of sets of acoustic transducers in the array to produce adjacent first acoustic measurements that are spaced a first distance D1 apart along the borehole wall, each set having at least one transducer that is different from an adjacent set, (ii) steers a second acoustic beam along the section of the borehole wall using one set of acoustic transducers in the array to produce adjacent second acoustic measurements that are a second distance D2 apart along the borehole wall, and (iii) images the borehole wall using the first acoustic measurements and the second acoustic measurement to generate a borehole wall image, wherein at least one second acoustic measurement is between adjacent first acoustic measurements.

Abstract: Methods, systems, and devices for downhole evaluation using a sensor assembly that includes a sensor plate, wherein a surface of the sensor plate forms a portion of an exterior surface of a downhole tool. Methods may include submerging the surface of the sensor plate in a downhole fluid in a borehole; activating the sensor assembly to generate a guided wave that propagates along the sensor plate, wherein propagation of the guided wave along the sensor plate is dependent upon a parameter of interest of the downhole fluid; and using information from the sensor assembly relating to the propagation of the guided wave along the sensor plate to estimate the parameter of interest. Methods may include isolating an opposing surface of the sensor plate from the downhole fluid. The guided wave may be an interface guided wave or may propagate in the plate between the surface and an opposing surface.

Abstract: Systems, devices, and methods for evaluating an earth formation intersected by a borehole using signals produced at a plurality of borehole depths by an ultrasonic transducer in the borehole, the signals produced by the transducer including ringdown signals from the ultrasonic transducer and echo signals from a wall of the borehole from a plurality of azimuthal orientations.

Abstract: An embodiment of an acoustic transducer assembly includes: a piezoelectric active element configured to emit acoustic signals, the active element having an emitting surface and a back surface located opposite the emitting surface, at least a portion of the back surface having a shape that forms a curve, the shape configured to cause the active element to have a variable thickness between the emitting surface and the back surface; and a backing material disposed in contact with the backing surface and configured to absorb the acoustic signals, the backing material shaped to conform to the back surface.

Abstract: An apparatus for estimating a property of a subsurface material includes a carrier configured to convey an acoustic wave guide though a borehole. The acoustic wave guide includes an acoustic plate configured to guide an acoustic wave along a path of the plate and an acoustic reservoir coupled to the acoustic plate and at least partially surrounding the acoustic plate. The acoustic reservoir has a mass greater than the mass of the acoustic plate and is configured to absorb acoustic wave leakage from the acoustic plate. A first acoustic transducer is coupled to the acoustic plate and configured to transmit an acoustic wave along the path. A second acoustic transducer is coupled to the acoustic plate and configured to receive the acoustic wave that travels along the path. A controller is configured to operate the first acoustic transducer and the second acoustic transducer in order to estimate the property.

Abstract: An acoustic transducer assembly includes: a carrier configured to be disposed in an earth formation, the carrier having a carrier axis; an array of transducer elements forming at least a semicircular shape, the array configured to emit acoustic signals in a radial direction relative to the carrier axis; and a circuit coupled to the array and configured to actuate a subset of the transducer elements and emit an acoustic beam therefrom, the circuit configured to actuate the subsets as a phased array to electronically rotate the acoustic beam about the carrier axis.

Abstract: An apparatus for imaging a borehole wall includes an array of acoustic transducers and a controller. The controller scans a section of the borehole wall with first acoustic beams that are transmitted by a series of sets of acoustic transducers in the array to produce adjacent first acoustic measurements that are spaced a first distance D1 apart along the borehole wall, each set having at least one transducer that is different from an adjacent set, (ii) steers a second acoustic beam along the section of the borehole wall using one set of acoustic transducers in the array to produce adjacent second acoustic measurements that are a second distance D2 apart along the borehole wall, and (iii) images the borehole wall using the first acoustic measurements and the second acoustic measurement to generate a borehole wall image, wherein at least one second acoustic measurement is between adjacent first acoustic measurements.

Abstract: An apparatus for estimating a property of a subsurface material includes a carrier configured to convey an acoustic wave guide though a borehole. The acoustic wave guide includes an acoustic plate configured to guide an acoustic wave along a path of the plate and an acoustic reservoir coupled to the acoustic plate and at least partially surrounding the acoustic plate. The acoustic reservoir has a mass greater than the mass of the acoustic plate and is configured to absorb acoustic wave leakage from the acoustic plate. A first acoustic transducer is coupled to the acoustic plate and configured to transmit an acoustic wave along the path. A second acoustic transducer is coupled to the acoustic plate and configured to receive the acoustic wave that travels along the path. A controller is configured to operate the first acoustic transducer and the second acoustic transducer in order to estimate the property.

Abstract: Methods, systems, and devices for downhole evaluation using a sensor assembly that includes a sensor plate, wherein a surface of the sensor plate forms a portion of an exterior surface of a downhole tool. Methods may include submerging the surface of the sensor plate in a downhole fluid in a borehole; activating the sensor assembly to generate a guided wave that propagates along the sensor plate, wherein propagation of the guided wave along the sensor plate is dependent upon a parameter of interest of the downhole fluid; and using information from the sensor assembly relating to the propagation of the guided wave along the sensor plate to estimate the parameter of interest. Methods may include isolating an opposing surface of the sensor plate from the downhole fluid. The guided wave may be an interface guided wave or may propagate in the plate between the surface and an opposing surface.

Abstract: An embodiment of an acoustic transducer assembly includes: a piezoelectric active element configured to emit acoustic signals, the active element having an emitting surface and a back surface located opposite the emitting surface, at least a portion of the back surface having a shape that forms a curve, the shape configured to cause the active element to have a variable thickness between the emitting surface and the back surface; and a backing material disposed in contact with the backing surface and configured to absorb the acoustic signals, the backing material shaped to conform to the back surface.

Abstract: An acoustic transducer assembly includes: a carrier configured to be disposed in an earth formation, the carrier having a carrier axis; an array of transducer elements forming at least a semicircular shape, the array configured to emit acoustic signals in a radial direction relative to the carrier axis; and a circuit coupled to the array and configured to actuate a subset of the transducer elements and emit an acoustic beam therefrom, the circuit configured to actuate the subsets as a phased array to electronically rotate the acoustic beam about the carrier axis.

Abstract: Measurements made by a transducer assembly for downhole imaging are affected by reverberations between the transducer and the window on the outside of the assembly. The reverberations result in a stationary noise on the image. Hardware solutions to improve signal-to-noise ratio includes using a composite transducer, adjusting the distance between the transducer and the window. SNR can also be improved by processing techniques that include stacking, fitting a sinusoid to the reverberation, by envelope peak detection, and by applying a notch filter.

Abstract: Measurements made by a transducer assembly for downhole imaging are affected by reverberations between the transducer and the window on the outside of the assembly. The reverberations result in a stationary noise on the image. Hardware solutions to improve signal-to-noise ratio includes using a composite transducer, adjusting the distance between the transducer and the window. SNR can also be improved by processing techniques that include stacking, fitting a sinusoid to the reverberation, by envelope peak detection, and by applying a notch filter.

Abstract: Measurements made by a transducer assembly for downhole imaging are affected by reverberations between the transducer and the window on the outside of the assembly. The reverberations result in a stationary noise on the image. Hardware solutions to improve signal-to-noise ratio includes using a composite transducer, adjusting the distance between the transducer and the window. SNR can also be improved by processing techniques that include stacking, fitting a sinusoid to the reverberation, by envelope peak detection, and by applying a notch filter.

Abstract: The present disclosure relates to methods and apparatuses measuring a property of a material. The apparatus may include a transducer comprising a first electrical conductor, a second electrical conductor, and a piezoelectric component configured to receive the two conductors. The piezoelectric component may include a cavity dimensioned to improve the strength of or reduce stress on an interconnection between piezoelectric component and at least one of the conductors. The method may include using one or more transducers measuring a property of a material. In some embodiments, the material may be an earth formation.

Abstract: A stop collar assembly used for axially securing and/or to resist axial sliding of a downhole tool device. The assembly provided on a housing of the downhole tool and includes a generally annular ring having an inner circumference beveled outward proximate to the ring edge. A clamp ring having a raised portion on its outer surface is disposed adjacent and substantially coaxial with the annular ring. Pushing the annular ring against the clamp ring compresses the clamp ring onto the housing to resist axial sliding of the annular ring.

Abstract: The downhole tool disclosed herein comprises a body, a flexible member attached to the body, and a transducer housed in the body. The flexible member compresses against one side of the wellbore and urges the body against the other side. The transducer emits a signal to the flexible member reflectable from the flexible member back to the transducer. The signal travel time from the transducer to the flexible member and back is analyzed for estimating the distance between the body and the flexible member. The standoff distance can be estimated from the distance between the body and the flexible member. From the standoff distance, the wellbore diameter is estimated. The tool may also obtain wellbore dimensions by obtaining near side wellbore standoff and using a magnetic ruler to determine bowspring flexing. The magnetic ruler results may be used in conjunction with or without the far side standoff data.