Abstract: A technique facilitates cement bonding evaluation including collecting waveform data and pre-processing the waveform data. The technique also may utilize processes which provide a time window position for the pre-processed waveform data and calculation of waveform amplitude and/or attenuation. Additionally, the technique may include deriving an amplitude-based bond index and/or attenuation-based bond index through the use of a model or other suitable waveform data processing technique which enables preparation of quality control plots with respect to the processing results.

Abstract: An acoustic signal is transmitted from a downhole tool positioned within a wellbore. Amplitudes and travel times of the acoustic signal received at different azimuthal locations of the downhole tool are measured. Correction factors, each corresponding to a different one of the measured amplitudes, are determined based on the travel times measured at each of the different azimuthal locations. Corrected amplitudes are each determined based on the corresponding measured amplitude and the corresponding correction factor.

Abstract: A downhole tool having a transmitter array with azimuthally spaced transmitters and receiver arrays with azimuthally spaced receivers. Methods of operation include transmitting an acoustic signal from an individual one of the transmitters, sensing an attribute of the acoustic signal with the receivers, and evaluating a characteristic of a portion of a downhole feature based on response signals generated by the first and second receivers. Each response signal is indicative of the acoustic signal attribute sensed by the corresponding receivers. This is repeated with different individual ones of the transmitters and receivers until the evaluated portions of the downhole feature collectively extend around a wellbore.

Abstract: A method of quantitative cement evaluation is provided. The method includes deploying a logging-while-drilling downhole sonic tool into a wellbore inside a casing, measuring acoustic signals propagating through the casing with the logging-while-drilling downhole sonic tool, and performing quantitative cement evaluation with respect to cement bonding around the casing by using waveform data of the acoustic signals measured with the logging-while-drilling downhole sonic tool.

Abstract: A downhole tool for operation within a wellbore and including a transmitter array and first and second receiver arrays. The transmitter array includes a plurality of transmitters azimuthally distributed around a longitudinal axis of the downhole tool at a first axial location of the downhole tool. The first receiver array includes a plurality of first receivers azimuthally distributed around the longitudinal axis at a second axial location axially offset from the first axial location. The second receiver array includes a plurality of second receivers azimuthally distributed around the longitudinal axis at a third axial location axially offset from the first and second axial locations.

Abstract: An acoustic signal is transmitted from a downhole tool positioned within a wellbore. Amplitudes and travel times of the acoustic signal received at different azimuthal locations of the downhole tool are measured. Correction factors, each corresponding to a different one of the measured amplitudes, are determined based on the travel times measured at each of the different azimuthal locations. Corrected amplitudes are each determined based on the corresponding measured amplitude and the corresponding correction factor.

Abstract: A downhole tool having a transmitter array with azimuthally spaced transmitters and receiver arrays with azimuthally spaced receivers. Methods of operation include transmitting an acoustic signal from an individual one of the transmitters, sensing an attribute of the acoustic signal with the receivers, and evaluating a characteristic of a portion of a downhole feature based on response signals generated by the first and second receivers. Each response signal is indicative of the acoustic signal attribute sensed by the corresponding receivers. This is repeated with different individual ones of the transmitters and receivers until the evaluated portions of the downhole feature collectively extend around a wellbore.

Abstract: A downhole tool for operation within a wellbore and including a transmitter array and first and second receiver arrays. The transmitter array includes a plurality of transmitters azimuthally distributed around a longitudinal axis of the downhole tool at a first axial location of the downhole tool. The first receiver array includes a plurality of first receivers azimuthally distributed around the longitudinal axis at a second axial location axially offset from the first axial location. The second receiver array includes a plurality of second receivers azimuthally distributed around the longitudinal axis at a third axial location axially offset from the first and second axial locations.

Abstract: A technique facilitates removal of noise from sonic logging signals. The technique may comprise various approaches used alone or in combination to reduce or eliminate noise associated with tool arrival. The technique may comprise an active cancellation approach which optimizes the cancellation effect while having minimal impact on the desired acoustic signals. The techniques also may utilize an asynchronous noise cancellation approach with a calibration transmitter designed to minimize impact on the desired acoustic signals.

Abstract: A technique facilitates cement bonding evaluation including collecting waveform data and pre-processing the waveform data. The technique also may utilize processes which provide a time window position for the pre-processed waveform data and calculation of waveform amplitude and/or attenuation. Additionally, the technique may include deriving an amplitude-based bond index and/or attenuation-based bond index through the use of a model or other suitable waveform data processing technique which enables preparation of quality control plots with respect to the processing results.

Abstract: A method of quantitative cement evaluation is provided. The method includes deploying a logging-while-drilling downhole sonic tool into a wellbore inside a casing, measuring acoustic signals propagating through the casing with the logging-while-drilling downhole sonic tool, and performing quantitative cement evaluation with respect to cement bonding around the casing by using waveform data of the acoustic signals measured with the logging-while-drilling downhole sonic tool.

Abstract: An apparatus disclosed herein includes a shell movably coupled to a base. The shell defines a chamber, and a counterweight is disposed in the chamber. A first spring is coupled to the shell and a first end of the counterweight, and a second spring is coupled to the shell and a second end of the counterweight. The first spring is oriented at a first angle, and the second spring is oriented at a second angle different than the first angle. The example apparatus further includes an actuator coupled to the first spring or the second spring. The actuator is to oscillate the counterweight to enable the shell to provide an acoustic signal.

Abstract: An improvement of an anti-rust cover for covering the outer side of a disc rotor of a vehicle disc brake. The anti-rust cover, which is capable of removably attached to the outer periphery of a dust cover, for covering the inner side of the disc rotor, at its outer periphery is characterized in that an engaging member disposed, on the inner surface and in the vicinity of the outer periphery, thereof for being engaged with the outer periphery of the dust cover, is utilized to afford a recess portion large enough to allow at least a part of a human finger to be held therein, and the anti-rust cover can be easily removed by means of holding a finger in the recess portion when required to be taken away.

Abstract: An improved anti-rust cover for covering the outer side of a disc rotor of a vehicle disc brake. The anti-rust cover, which is capable of removably attached to the outer periphery of a dust cover for covering the inner side of the disc rotor at its outer periphery, is characterized in that the same is provided with a bridge portion formed by partly narrowing the width of the annular portion thereof and a detoured path portion formed by protruding a part of the bridge portion outwardly from base of the bridge portion to encircle a gate shaped open space in it.