Abstract: An embodiment of a method of estimating characteristics of an earth formation includes: disposing an acoustic tool in a borehole in an earth formation, the acoustic tool including an acoustic multipole transmitter and at least one multipole acoustic receiver; transmitting acoustic signals into the borehole, the acoustic signals generating at least one acoustic body wave that radiates away from the borehole into a far-field formation region; measuring reflected signals including body waves reflected from reflective boundaries in the far-field formation region; identifying a reflective boundary in the formation and reflection attributes associated with the reflective boundary; and estimating at least one of a thickness, distance and a lateral extent of a hydrocarbon formation feature based on the reflected signals and the reflection attributes.

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: A method of estimating fractures in an earth formation includes: disposing an acoustic tool in a cased borehole in an earth formation, the acoustic tool including a multipole acoustic transmitter and an acoustic receiver; transmitting an acoustic signal into the borehole; measuring deep shear wave (DSW) signals generated from shear body waves reflected in the formation in a far-field region of the formation around the borehole; and estimating at least a location and an orientation of a fracture in the formation based on the DSW signals.

Abstract: Systems, devices and methods for evaluating an earth formation intersected by a borehole. Method include detecting a reflective boundary in the earth formation by: generating a multipole acoustic signal with a logging tool in the borehole; identifying a shear wave signal resulting from shear body waves reflected in the formation in a near-field region of the formation around the borehole responsive to the generated multipole acoustic signal; and estimating at least a depth along the borehole of the boundary based on the shear wave signal. The boundary may have an angle of incidence with respect to the borehole of greater than 70 degrees. The boundary may be at least one of i) a fracture; and ii) a fault. The method may include evaluating the boundary using at least one attribute of the shear wave signal and the estimated depth.

Abstract: Disclosed herein is a method of delineating a second wellbore from a first wellbore. The method includes, emitting acoustic waves from a tool in the first wellbore, receiving acoustic waves at the tool reflected from the second wellbore, and determining orientation and distance of at least a portion of the second wellbore relative to the tool.

Abstract: An embodiment of a method of estimating characteristics of an earth formation includes: disposing an acoustic tool in a borehole in an earth formation, the acoustic tool including an acoustic multipole transmitter and at least one multipole acoustic receiver; transmitting acoustic signals into the borehole, the acoustic signals generating at least one acoustic body wave that radiates away from the borehole into a far-field formation region; measuring reflected signals including body waves reflected from reflective boundaries in the far-field formation region; identifying a reflective boundary in the formation and reflection attributes associated with the reflective boundary; and estimating at least one of a thickness, distance and a lateral extent of a hydrocarbon formation feature based on the reflected signals and the reflection attributes.

Abstract: The present disclosure is related to apparatuses and methods measuring and processing a characteristic of subsurface earth formations penetrated by a borehole. More specifically this present disclosure relates to a method and apparatus for measuring and processing an acoustic characteristic such as formation shear wave velocity of subsurface sonic waves after these waves traverse earth formations adjoining a borehole or passing through a portion of the subsurface. The apparatus may include: a bottomhole assembly, a drill bit configured to generate an acoustic signal, at least two acoustic detectors, and a processor. The acoustic signal may include a specific multipole signal that may propagate through an earth formation along the borehole. The method may include use of the apparatus, including steps for estimating a shear velocity of the acoustic signal using signals from the at least two acoustic detectors.

Abstract: A method of estimating fractures in an earth formation includes: disposing an acoustic tool in a cased borehole in an earth formation, the acoustic tool including a multipole acoustic transmitter and an acoustic receiver; transmitting an acoustic signal into the borehole; measuring deep shear wave (DSW) signals generated from shear body waves reflected in the formation in a far-field region of the formation around the borehole; and estimating at least a location and an orientation of a fracture in the formation based on the DSW signals.

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: Disclosed is a method implemented by a processor for imaging a formation penetrated by a borehole. The method includes: obtaining acoustic data in a depth-time domain using an acoustic downhole tool disposed at a depth in the borehole, the acoustic downhole tool having an acoustic source and an acoustic receiver; transforming the acoustic data in the depth-time domain into a Radon domain using a Radon transform; filtering the acoustic data in the Radon domain to increase a signal of interest in the acoustic data in the Radon domain; determining a location of a point in the formation that reflected acoustic energy emitted from the acoustic source to the acoustic receiver, the location of the point being represented in the Radon domain; and inverting the location of the point represented in the Radon domain into a radius-depth domain to image the formation.

Abstract: A stepped reflector on the outside of a bottomhole assembly produces two reflections in response to excitation of a transducer. The velocity of the fluid in the borehole is estimated using the two reflections. Alternatively, a change in the gas content of the borehole fluid is estimated from changes in the electrical impedance of a transducer in contact with the borehole fluid.

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 of impedance are made using a piezoelectric transducer oriented at different angles to a formation bedding plane. The impedance measurements are then used to estimate the anisotropic velocity of the formation.

Abstract: A method for estimating a slowness of an earth formation, the method including: transmitting acoustic energy into the earth formation using an acoustic source; receiving the acoustic energy with an array of acoustic receivers, each acoustic receiver being configured to provide acoustic waveform data related to the received acoustic energy; transforming the acoustic waveform data into a frequency domain to provide frequency domain data; calculating a slowness-frequency coherence function using the frequency domain data; selecting slowness dispersion data from peaks of the slowness-frequency coherence function; fitting a curve to the slowness dispersion data; and estimating the slowness from the curve.

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: The present disclosure relates to methods and apparatuses for estimating a parameter of interest of an earth formation. The method may include using an acoustic sensor azimuthally positioned relative to a monopole acoustic source to reduce at least one high-order mode due to the monopole acoustic source. The monopole acoustic source may include one or more acoustic elements. The method may include generating a monopole acoustic pulse. The apparatus may include at least one acoustic source element and at least one acoustic sensor disposed on a housing configured for conveyance in a borehole. The at least one acoustic sensor may be azimuthally positioned relative to the at least one acoustic source to reduce at least one high-order mode.

Abstract: A radial shear velocity profile of an earth formation is obtained by using dipole and/or cross-dipole measurements. The non-uniqueness in the inversion is addressed by using a constraint based on the fact that high-frequency dipole shear waves are mostly sensitive to the near-borehole shear velocity.

Abstract: An apparatus and method for providing a downhole acoustic source is disclosed. The acoustic source includes a piston configured to oscillate in an axial direction of the acoustic source and produce an acoustic signal in a medium in contact with an exterior surface of the piston, and an elastomer disposed on an interior side of the piston, an acoustic impedance of the elastomer selected to match an acoustic impedance of the piston. A permanent magnet is configured to provide a permanent magnetic field oriented in the axial direction, and a coil disposed on an interior side of the piston produces an alternating magnetic field in the region of the permanent magnetic field. The elastomer may be, for example, a silicon rubber, a silicone jelly, and a silicone oil. A plurality of acoustic sources may be arranged to produce an acoustic dipole configuration or an acoustic quadrupole configuration.

Abstract: Disclosed is a method implemented by a processor for imaging a formation penetrated by a borehole. The method includes: obtaining acoustic data in a depth-time domain using an acoustic downhole tool disposed at a depth in the borehole, the acoustic downhole tool having an acoustic source and an acoustic receiver; transforming the acoustic data in the depth-time domain into a Radon domain using a Radon transform; filtering the acoustic data in the Radon domain to increase a signal of interest in the acoustic data in the Radon domain; determining a location of a point in the formation that reflected acoustic energy emitted from the acoustic source to the acoustic receiver, the location of the point being represented in the Radon domain; and inverting the location of the point represented in the Radon domain into a radius-depth domain to image the formation.