Abstract: An apparatus for simultaneous logging presenting a capability to perform multipole sonic and acoustic reflection surveys for near-borehole and far field imaging.

Abstract: A technique facilitates determination of a quantitative bond between a pipe and adjacent materials, e.g. between a wellbore casing and adjacent cement. The quantitative bond is established via acoustic measurements related to signal attenuation. Additionally, the acoustic measurements may be conducted with a sonic tool during a wellbore operation, e.g. during a drilling operation. The methodology enables use of signal attenuation in a manner which facilitates determination of bond index coverage up to a high percentage, e.g. 100 percent.

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: Acoustic signals sent by a logging tool disposed in a borehole are detected by receivers located on the logging tool. Time domain representations of the detected acoustic signals are converted into frequency domain representations. Then at least one frequency range is selected and the detected acoustic signals corresponding to each selected frequency range are filtered. Eigenvectors for the filtered data for each selected frequency range are computed and dependence of the eigenvectors on the frequency is obtained. System for processing acoustic signals comprises a computer in communication with the logging tool and a set of instructions executable by the computer.

Abstract: A tool for monopole and multipole sonic logging includes an acoustic source section, an acoustic receiver section, and an isolator section disposed therebetween. The tool may include a mandrel having integrally formed alternating first portions having a first outer diameter and second portions having a second outer diameter. The second outer diameter is smaller than the first outer diameter, which allows the portions to function acoustically as a mass and spring system. The isolator section sufficiently mutes or delays extensional and flexural modes intrinsic to the logging tool itself. Thus, the effects of the tool presence on the measurements are minimized. In addition, a plurality of axially oriented grooves are defined in an outer surface of the acoustic receiver section, and each groove is configured for receiving an acoustic receiver module that includes a sensor, an amplifier, an A/D converter, and a digital multiplexer.

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: Apparatus for acoustic measurement in a downhole environment to enable high quality measurements to be obtained in difficult logging conditions are disclosed. An example apparatus includes a downhole tool having a body with a plurality of transmitters located on the body. A receiver is located on the body a distance from the transmitters and an attenuator section is integrally formed on the body between at least one transmitter and the receiver.

Abstract: An example method for displaying sonic logging data associated with a formation surrounding a borehole can include acquiring sonic data at a plurality of depths using an acoustic array located in the borehole and transforming the acquired sonic data from a time-space domain to a frequency-wave number domain at a limited number of discrete frequencies. The method can also include estimating slowness values at the limited number of discrete frequencies from the transformed sonic data, interpolating the estimated slowness values to obtain a projection of one or more slowness-frequency dispersions of the acquired sonic data and displaying the projection of the slowness-frequency dispersions. The projection of the slowness-frequency dispersions can include a plurality of color bands corresponding to each of the limited number of discrete frequencies.

Abstract: Methods and related systems are described relating to a sealed acoustic transducer assembly for use in a wellbore is provided. A tool body is deployed in the wellbore, having a groove and a sealed acoustic transducer assembly removeably mounted therein. The transducer assembly includes an acoustic transducer element, and an elongated fluid filled sealed container housing the transducer element. The container includes flexible portions along the length of the container which allows for volume changes when exposed to changes in external pressure and/or temperature. Acoustic measurements downhole are made using the transducer element.

Abstract: A technique facilitates determination of a quantitative bond between a pipe and adjacent materials, e.g. between a wellbore casing and adjacent cement. The quantitative bond is established via acoustic measurements related to signal attenuation. Additionally, the acoustic measurements may be conducted with a sonic tool during a wellbore operation, e.g. during a drilling operation. The methodology enables use of signal attenuation in a manner which facilitates determination of bond index coverage up to a high percentage, e.g. 100 percent.

Abstract: A tool for monopole and multipole sonic logging includes an acoustic source section, an acoustic receiver section, and an isolator section disposed therebetween. The tool may include a mandrel having integrally formed alternating first portions having a first outer diameter and second portions having a second outer diameter. The second outer diameter is smaller than the first outer diameter, which allows the portions to function acoustically as a mass and spring system. The isolator section sufficiently mutes or delays extensional and flexural modes intrinsic to the logging tool itself. Thus, the effects of the tool presence on the measurements are minimized. In addition, a plurality of axially oriented grooves are defined in an outer surface of the acoustic receiver section, and each groove is configured for receiving an acoustic receiver module that includes a sensor, an amplifier, an A/D converter, and a digital multiplexer.

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 example method for displaying sonic logging data associated with a formation surrounding a borehole can include acquiring sonic data at a plurality of depths using an acoustic array located in the borehole and transforming the acquired sonic data from a time-space domain to a frequency-wave number domain at a limited number of discrete frequencies. The method can also include estimating slowness values at the limited number of discrete frequencies from the transformed sonic data, interpolating the estimated slowness values to obtain a projection of one or more slowness-frequency dispersions of the acquired sonic data and displaying the projection of the slowness-frequency dispersions. The projection of the slowness-frequency dispersions can include a plurality of color bands corresponding to each of the limited number of discrete frequencies.

Abstract: Example methods, apparatus and articles of manufacture to determine anisotropy indicators for subterranean formations are disclosed. A disclosed example method includes computing a first shear slowness value from measured quadrupole waves, computing a second shear slowness value from measured Stoneley waves, and comparing the first and second shear slowness values to determine an anisotropy indicator representative of anisotropy of a subterranean formation.

Abstract: Methods and related systems are described relating to a sealed acoustic transducer assembly for use in a wellbore is provided. A tool body is deployed in the wellbore, having a groove and a sealed acoustic transducer assembly removeably mounted therein. The transducer assembly includes an acoustic transducer element, and an elongated fluid filled sealed container housing the transducer element. The container includes flexible portions along the length of the container which allows for volume changes when exposed to changes in external pressure and/or temperature. Acoustic measurements downhole are made using the transducer element.

Abstract: Methods and related systems are described relating to a sealed acoustic transducer assembly for use in a wellbore is provided. One or more acoustic transducer elements, which can be receivers or transmitters, are housed in an elongated fluid filled sealed container. The sealed container is adapted to be removeably mounted to a portion of a drill collar. The container, which for example can be made of thin corrugated metal or rubber, includes flexible portions along the length of the container which allows for volume changes when exposed to changes in external pressure and/or temperature.

Abstract: Apparatus for acoustic measurement in a downhole environment to enable high quality measurements to be obtained in difficult logging conditions are disclosed. An example apparatus includes a downhole tool having a body with a plurality of transmitters located on the body. A receiver is located on the body a distance from the transmitters and an attenuator section is integrally formed on the body between at least one transmitter and the receiver.

Abstract: A solar cell includes a crystalline semiconductor substrate having one of a p-type and an n-type material, a p-type semiconductor layer formed on a first principal surface of the substrate, a first transparent conductive film comprising indium oxide containing hydrogen and cerium and formed on the p-type semiconductor layer, an n-type semiconductor layer formed on a second principal surface of the substrate, and a second transparent conductive film comprising indium oxide containing no cerium and formed on the n-type semiconductor layer.

Abstract: Example methods, apparatus and articles of manufacture to determine anisotropy indicators for subterranean formations are disclosed. A disclosed example method includes computing a first shear slowness value from measured quadrupole waves, computing a second shear slowness value from measured Stoneley waves, and comparing the first and second shear slowness values to determine an anisotropy indicator representative of anisotropy of a subterranean formation.

Abstract: An i-type amorphous silicon layer 14 and a p-type amorphous silicon layer 15 are formed on a part of an inner wall of a through hole of an n-type single-crystal silicon substrate 11. Further, an i-type amorphous silicon layer 12 and an n-type amorphous silicon layer 13 are formed on a part of the inner wall of the through hole of the n-type single-crystal silicon substrate 11. The inner wall surface of the through hole is covered with the i-type amorphous silicon layer 14 and the i-type amorphous silicon layer 12.