Christoph Klieber

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Research Highlights

Acoustic Sensor Development
Visualizing Wave Propagration
Beamshaping and Beamforming
Ultra-Broadband Acoustic Measurements
Nonlinear Acoustics

 

Acoustic Sensor Development

Photos and figures from reference: New-Generation Ultrasonic Measurements for Quantitative Cement Evaluation in Heavy Muds and Thick-Wall Casings, SPE ATCE, SPE-181450-MS.

Ultrasonic nondestructive testing for environmental safety evaluation of subterrain wells such as PowerECHO* depends on robust ultrasonic transducers which operate reliably under extreme environmental conditions (temperatures exceeding 175°C and pressures exceeding 2000 bar). This requirement makes transducer development and construction very challenging. Laboratory studies and numerical simulations of complete ultrasonic transducer allow to fully understand internal and external wave propagation during wave emission and upon reception of reflected waves. Much effort has to be invested to obtain a good handle on non-trivial parameters for all of the transducer parts, using input from experimental data to calibrate effects such as frequency dependence of backing dampening and piezoelectric interactions. Such an in depth study allows capturing all relevant physical phenomena and results in a solid understanding of their impact on the measurement to ultimately engineer the sensor hardware to its best possible performance. Validation measurements covering the full muldi-dimensional space of possible environmental conditions were carried out to verify its proper performance.
* Mark of Schlumberger

Understanding and Optimizing Measurements Through Wave Visualization

Photos and figures from reference: New-Generation Ultrasonic Measurements for Quantitative Cement Evaluation in Heavy Muds and Thick-Wall Casings, SPE ATCE, SPE-181450-MS.

Needle hydrophone measurements visualize full acoustic wave propagation of the flexural wave measurement as it is used in commercial cement evaluation services such as the IsolationScanner* and PowerFLEX*.
* Mark of Schlumberger

Beamshaping and Beamforming

Figures reproduced from reference: Narrow-Band Acoustic Attenuation Measurements in Vitreous Silica at Frequencies Between 20 and 400 GHz, C. Klieber et al., Appl. Phys. Lett. 98, 211908 (2011).

Beamshaping and Beamforming are powerful methods to focus acoustic or optical energy either spatially or into a certain frequency range. This opens up the possibility to conduct measurements examining small spatial features or when signal-to-noise levels would otherwise not allow it.

Ultra-Broadband Acoustic Measurements

Figures reproduced from reference: Toward broadband mechanical spectroscopy, T. Hecksher et al., Proceedings of the National Academy of Sciences 114(33), 2017.

Viscous liquids of all kinds, from honey to glycerol to common polymers, display remarkably similar dynamical properties upon cooling from high temperatures at which local structural relaxation and flow occur quickly, to moderate temperatures at which key components of the dynamics slow down dramatically, to cold temperatures at which a glassy solid is formed. The similarities suggest a common theoretical framework, but comprehensive measurements of liquids’ mechanical properties covering the extraordinary range of time scales spanned have been elusive. Using seven experimental methods covering 13 decades in frequency with few gaps, we demonstrate that broadband mechanical spectra are now within reach.

Nonlinear Acoustics

Figures reproduced from references: Femtosecond imaging of nonlinear acoustics in gold, T. Pezeril et al., Optics Express, 22(4), 4590-4598 (2014) and Nonlinear Phasing and Dephasing of Three Wave Mixing of Acoustic Guided Waves, C. Klieber et al., Phys. Rev. E 88, 033204 (2013).

Our world is linear only in first approximation. For example, when one pulls on a spring or rubber band a little harder, the linear force-elongation relationship stops to be valid and the system first enters a reversible, nonlinear regime before it plastically deforms and ultimately fails (e.g. the rubber band tears). Nonlinear measurements in the elastic regime are a powerful tool in nondestructive testing to evaluate material properties, and detect alterations and damage to a sample. For example, we investigated the potential of such measurements for early signs of borehole failure by exploiting nonlinear tubewave (Stoneley wave) propagation.

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