Pierre-Yves Le Bas | Los Alamos National Laboratory (original) (raw)

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Papers by Pierre-Yves Le Bas

Research paper thumbnail of Downhole nonlinear acoustics measurements in rock formations using dynamic acoustic elasticity and time reversal

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 8, 2021

Research paper thumbnail of Time-reversed nonlinear acoustics for downhole pressure measurements

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Aug 3, 2021

Research paper thumbnail of Time-reversed nonlinear acoustic downhole pore pressure measurements

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 20, 2021

Research paper thumbnail of Acoustic Imaging of Delaminations and Cracks Using Time Reversal and Nonlinear Spectroscopy Techniques

Research paper thumbnail of Nonlinear resonant ultrasound spectroscopy of stress corrosion cracking in stainless steel rods

NDT & E international, Mar 1, 2019

Research paper thumbnail of Nonlinearity from stress corrosion cracking as a function of chloride exposure time using the time reversed elastic nonlinearity diagnostic

Journal of the Acoustical Society of America, 2019

Research paper thumbnail of On the use of time reversal in the detection of buried nonlinear features

Research paper thumbnail of Knocking over LEGO minifigures with time reversal focused vibrations: Understanding the physics and developing a museum demonstration

Journal of the Acoustical Society of America, Oct 1, 2021

Time reversal (TR) of impulse responses can be used to focus wave energy, even in a reverberant e... more Time reversal (TR) of impulse responses can be used to focus wave energy, even in a reverberant environment. A demonstration of TR focusing was developed to knock over a targeted LEGO minifigure, standing among other minifigures (who remain standing), by focusing plate vibrations under the target minifigure\rquote s feet. In order to achieve a high degree of repeatability, the physics of the demonstration needed to be understood. A laser Doppler vibrometer was used to compare the motion of the minifigure and the plate directly beneath it. Speaker shakers are used to generate motion of the plate. If their induced vibration was too large the minifigure loses contact with the plate prematurely, causing it to be in the air when the main focused vibrations arrive. If the minifigure is in contact with the plate when the focused vibrations arrive then the minifigure is launched into the air before toppling on its side. This demonstration was optimized to be a two-player-game museum exhibit in a wave propagation museum hosted by ETH Zurich in Switzerland. This demonstration illustrates the power of focused vibrations.

Research paper thumbnail of Microdamage detection and monitoring using NEWS over a wide frequency range

Research paper thumbnail of Nonlinear acoustic signature in relation to crack density for thermally shocked CFRP

Research paper thumbnail of Nonlinearity based diagnosis and localisation techniques for microdamage detection

Research paper thumbnail of The physics of knocking over LEGO minifigures with time reversal focused vibrations for use in a museum exhibit

Journal of the Acoustical Society of America, Feb 1, 2022

Research paper thumbnail of Damage localisation technique using Nonlinear Time Reversal Acoustics

Research paper thumbnail of Modeling of non-linear interaction of waves in rock

Research paper thumbnail of Nonlinear Acoustic Testing for Concrete MaterialsEvaluation

Materials evaluation, 2017

Research paper thumbnail of Combining Nonlinear Elastic Wave Spectroscopy with Time Reversal techniques for microdamage imaging

Research paper thumbnail of Nonlinear Acoustics Applications for Near Wellbore Formation Evaluation

SPWLA 61st Annual Online Symposium Transactions, 2020

We present experimental and modeling results and a downhole logging tool concept resulting from a... more We present experimental and modeling results and a downhole logging tool concept resulting from a research collaboration between Chevron Energy Technology Company and Los Alamos National Laboratory investigating using nonlinear acoustics applications for natural fracture characterization and assessing near-wellbore mechanical integrity or drilling-induced damage. The generation of a scattered wave by noncollinear mixing of two acoustic plane waves in an acoustically nonlinear medium was first documented several decades ago. If the frequency ratio and convergence angle of the two waves and the compressional-to-shear velocity ratio of the medium where they intersect meet certain conditions, their interaction creates a scattered third wave, propagating in a predictable direction, with a frequency equal to the sum or difference between the two primary wave frequencies and an amplitude dependent on the nonlinearity at the intersection location. The conditions resulting in this scattering and the properties of the scattered wave are thus governed by the physics of the interaction, resulting in a set of “selection rules” that are the key to the measurement principle introduced here. If the two transmitted plane waves are oriented such that the third wave returns to the borehole, the phenomenon may be used as the basis for a logging tool measuring acoustic nonlinearity around the wellbore circumference, with a secondary measurement of the compressional-to-shear velocity ratio. Laboratory measurements supported by finite-difference and analytical modeling confirmed that the mixing of two plane compressional waves generated a shear wave as predicted by the selection rules in a large Berea sandstone block, confirming the potential for a downhole tool with a depth of investigation in the range 15 to 20 cm. Historical data show that nonlinearity in core samples is primarily caused by a lack of mechanical integrity. In the oil field, this may be microfractures in tight rock unconventional reservoirs or incipient near-wellbore failure while drilling. This prompts applications to fracture characterization and calibration of mechanical earth models. The main practical challenge for a downhole logging tool is injecting powerful directional acoustic energy into the formation. We envisage an openhole tool making sequential station measurements using transmitters built into hydraulically controlled pads contacting the borehole wall. Noncollinear mixing may be activated by maintaining the frequency of one transmitter constant while sweeping the other through the range of frequency ratios predicted by the selection rules, resulting in a received sum or difference frequency signal that rises to a peak and then falls. Alternatively, the frequency ratio may be maintained while steering one of the acoustic beams. The peak signal amplitude indicates the coefficient of nonlinearity, which is sensitive to lack of mechanical integrity caused by natural fractures or mechanical disaggregation. The frequency ratio at which it occurs is an indicator of the shear-to-compressional velocity at the location where the two beams cross. In this manner, a record of nonlinearity along or around the borehole can be envisaged. The physics of acoustic nonlinearity is well established, and our laboratory measurements have determined that the phenomenon of interest should occur and be measurable in the subsurface. Overcoming the engineering challenges would bring new formation evaluation insights unique to this measurement principle.

Research paper thumbnail of A comparison of impulse response modification techniques for time reversal with application to crack detection

The Journal of the Acoustical Society of America, 2019

Time reversal (TR) focusing used for nonlinear detection of cracks relies on the ability of the T... more Time reversal (TR) focusing used for nonlinear detection of cracks relies on the ability of the TR process to provide spatially localized, high-amplitude excitation. The high amplitude improves the ability to detect nonlinear features that are a signature of the motion of closed cracks. It follows that a higher peak focal amplitude than what can be generated with the traditional TR process will improve the detection capability. Modifying the time-reversed impulse response to increase the amplitude of later arrivals in the impulse response, while maintaining the phase information of all arrivals, increases the overall focal signal amplitude. A variety of existing techniques for increasing amplitude are discussed, and decay compensation TR, a technique wherein amplitude is increased according to the inverse of the amplitude envelope of the impulse response decay, is identified as the best modification technique for nonlinear crack detection. This technique increases the focal signal a...

Research paper thumbnail of Nonlinear resonant ultrasound spectroscopy of stress corrosion cracking in stainless steel rods

NDT & E International, 2018

Research paper thumbnail of Dynamic acousto-elastic testing of concrete with a coda-wave probe: comparison with standard linear and nonlinear ultrasonic techniques

Ultrasonics, 2017

The use of nonlinear acoustic techniques in solids consists in measuring wave distortion arising ... more The use of nonlinear acoustic techniques in solids consists in measuring wave distortion arising from compliant features such as cracks, soft intergrain bonds and dislocations. As such, they provide very powerful nondestructive tools to monitor the onset of damage within materials. In particular, a recent technique called dynamic acousto-elasticity testing (DAET) gives unprecedented details on the nonlinear elastic response of materials (classical and non-classical nonlinear features including hysteresis, transient elastic softening and slow relaxation). Here, we provide a comprehensive set of linear and nonlinear acoustic responses on two prismatic concrete specimens; one intact and one pre-compressed to about 70% of its ultimate strength. The two linear techniques used are Ultrasonic Pulse Velocity (UPV) and Resonance Ultrasound Spectroscopy (RUS), while the nonlinear ones include DAET (fast and slow dynamics) as well as Nonlinear Resonance Ultrasound Spectroscopy (NRUS). In addit...

Research paper thumbnail of Downhole nonlinear acoustics measurements in rock formations using dynamic acoustic elasticity and time reversal

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jun 8, 2021

Research paper thumbnail of Time-reversed nonlinear acoustics for downhole pressure measurements

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Aug 3, 2021

Research paper thumbnail of Time-reversed nonlinear acoustic downhole pore pressure measurements

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 20, 2021

Research paper thumbnail of Acoustic Imaging of Delaminations and Cracks Using Time Reversal and Nonlinear Spectroscopy Techniques

Research paper thumbnail of Nonlinear resonant ultrasound spectroscopy of stress corrosion cracking in stainless steel rods

NDT & E international, Mar 1, 2019

Research paper thumbnail of Nonlinearity from stress corrosion cracking as a function of chloride exposure time using the time reversed elastic nonlinearity diagnostic

Journal of the Acoustical Society of America, 2019

Research paper thumbnail of On the use of time reversal in the detection of buried nonlinear features

Research paper thumbnail of Knocking over LEGO minifigures with time reversal focused vibrations: Understanding the physics and developing a museum demonstration

Journal of the Acoustical Society of America, Oct 1, 2021

Time reversal (TR) of impulse responses can be used to focus wave energy, even in a reverberant e... more Time reversal (TR) of impulse responses can be used to focus wave energy, even in a reverberant environment. A demonstration of TR focusing was developed to knock over a targeted LEGO minifigure, standing among other minifigures (who remain standing), by focusing plate vibrations under the target minifigure\rquote s feet. In order to achieve a high degree of repeatability, the physics of the demonstration needed to be understood. A laser Doppler vibrometer was used to compare the motion of the minifigure and the plate directly beneath it. Speaker shakers are used to generate motion of the plate. If their induced vibration was too large the minifigure loses contact with the plate prematurely, causing it to be in the air when the main focused vibrations arrive. If the minifigure is in contact with the plate when the focused vibrations arrive then the minifigure is launched into the air before toppling on its side. This demonstration was optimized to be a two-player-game museum exhibit in a wave propagation museum hosted by ETH Zurich in Switzerland. This demonstration illustrates the power of focused vibrations.

Research paper thumbnail of Microdamage detection and monitoring using NEWS over a wide frequency range

Research paper thumbnail of Nonlinear acoustic signature in relation to crack density for thermally shocked CFRP

Research paper thumbnail of Nonlinearity based diagnosis and localisation techniques for microdamage detection

Research paper thumbnail of The physics of knocking over LEGO minifigures with time reversal focused vibrations for use in a museum exhibit

Journal of the Acoustical Society of America, Feb 1, 2022

Research paper thumbnail of Damage localisation technique using Nonlinear Time Reversal Acoustics

Research paper thumbnail of Modeling of non-linear interaction of waves in rock

Research paper thumbnail of Nonlinear Acoustic Testing for Concrete MaterialsEvaluation

Materials evaluation, 2017

Research paper thumbnail of Combining Nonlinear Elastic Wave Spectroscopy with Time Reversal techniques for microdamage imaging

Research paper thumbnail of Nonlinear Acoustics Applications for Near Wellbore Formation Evaluation

SPWLA 61st Annual Online Symposium Transactions, 2020

We present experimental and modeling results and a downhole logging tool concept resulting from a... more We present experimental and modeling results and a downhole logging tool concept resulting from a research collaboration between Chevron Energy Technology Company and Los Alamos National Laboratory investigating using nonlinear acoustics applications for natural fracture characterization and assessing near-wellbore mechanical integrity or drilling-induced damage. The generation of a scattered wave by noncollinear mixing of two acoustic plane waves in an acoustically nonlinear medium was first documented several decades ago. If the frequency ratio and convergence angle of the two waves and the compressional-to-shear velocity ratio of the medium where they intersect meet certain conditions, their interaction creates a scattered third wave, propagating in a predictable direction, with a frequency equal to the sum or difference between the two primary wave frequencies and an amplitude dependent on the nonlinearity at the intersection location. The conditions resulting in this scattering and the properties of the scattered wave are thus governed by the physics of the interaction, resulting in a set of “selection rules” that are the key to the measurement principle introduced here. If the two transmitted plane waves are oriented such that the third wave returns to the borehole, the phenomenon may be used as the basis for a logging tool measuring acoustic nonlinearity around the wellbore circumference, with a secondary measurement of the compressional-to-shear velocity ratio. Laboratory measurements supported by finite-difference and analytical modeling confirmed that the mixing of two plane compressional waves generated a shear wave as predicted by the selection rules in a large Berea sandstone block, confirming the potential for a downhole tool with a depth of investigation in the range 15 to 20 cm. Historical data show that nonlinearity in core samples is primarily caused by a lack of mechanical integrity. In the oil field, this may be microfractures in tight rock unconventional reservoirs or incipient near-wellbore failure while drilling. This prompts applications to fracture characterization and calibration of mechanical earth models. The main practical challenge for a downhole logging tool is injecting powerful directional acoustic energy into the formation. We envisage an openhole tool making sequential station measurements using transmitters built into hydraulically controlled pads contacting the borehole wall. Noncollinear mixing may be activated by maintaining the frequency of one transmitter constant while sweeping the other through the range of frequency ratios predicted by the selection rules, resulting in a received sum or difference frequency signal that rises to a peak and then falls. Alternatively, the frequency ratio may be maintained while steering one of the acoustic beams. The peak signal amplitude indicates the coefficient of nonlinearity, which is sensitive to lack of mechanical integrity caused by natural fractures or mechanical disaggregation. The frequency ratio at which it occurs is an indicator of the shear-to-compressional velocity at the location where the two beams cross. In this manner, a record of nonlinearity along or around the borehole can be envisaged. The physics of acoustic nonlinearity is well established, and our laboratory measurements have determined that the phenomenon of interest should occur and be measurable in the subsurface. Overcoming the engineering challenges would bring new formation evaluation insights unique to this measurement principle.

Research paper thumbnail of A comparison of impulse response modification techniques for time reversal with application to crack detection

The Journal of the Acoustical Society of America, 2019

Time reversal (TR) focusing used for nonlinear detection of cracks relies on the ability of the T... more Time reversal (TR) focusing used for nonlinear detection of cracks relies on the ability of the TR process to provide spatially localized, high-amplitude excitation. The high amplitude improves the ability to detect nonlinear features that are a signature of the motion of closed cracks. It follows that a higher peak focal amplitude than what can be generated with the traditional TR process will improve the detection capability. Modifying the time-reversed impulse response to increase the amplitude of later arrivals in the impulse response, while maintaining the phase information of all arrivals, increases the overall focal signal amplitude. A variety of existing techniques for increasing amplitude are discussed, and decay compensation TR, a technique wherein amplitude is increased according to the inverse of the amplitude envelope of the impulse response decay, is identified as the best modification technique for nonlinear crack detection. This technique increases the focal signal a...

Research paper thumbnail of Nonlinear resonant ultrasound spectroscopy of stress corrosion cracking in stainless steel rods

NDT & E International, 2018

Research paper thumbnail of Dynamic acousto-elastic testing of concrete with a coda-wave probe: comparison with standard linear and nonlinear ultrasonic techniques

Ultrasonics, 2017

The use of nonlinear acoustic techniques in solids consists in measuring wave distortion arising ... more The use of nonlinear acoustic techniques in solids consists in measuring wave distortion arising from compliant features such as cracks, soft intergrain bonds and dislocations. As such, they provide very powerful nondestructive tools to monitor the onset of damage within materials. In particular, a recent technique called dynamic acousto-elasticity testing (DAET) gives unprecedented details on the nonlinear elastic response of materials (classical and non-classical nonlinear features including hysteresis, transient elastic softening and slow relaxation). Here, we provide a comprehensive set of linear and nonlinear acoustic responses on two prismatic concrete specimens; one intact and one pre-compressed to about 70% of its ultimate strength. The two linear techniques used are Ultrasonic Pulse Velocity (UPV) and Resonance Ultrasound Spectroscopy (RUS), while the nonlinear ones include DAET (fast and slow dynamics) as well as Nonlinear Resonance Ultrasound Spectroscopy (NRUS). In addit...

Research paper thumbnail of Ultrasonic radiation from wedges of cubic profile: Experimental results

This paper presents experimental results demonstrating the increase in ultrasonic radiation obtai... more This paper presents experimental results demonstrating the increase in ultrasonic radiation obtained from a wedge of cubic profile relative to a plate of uniform thickness. The wedge of cubic profile provides high efficiency sound radiation matching layer from a mounted piezoelectric transducer into the surrounding air. Previous research on structures with indentations of power-law profile has focused on vibration mitigation using the so called "acoustic black-hole" effect, whereas here such structures are used to enhance ultrasonic radiation. The work provides experimental verification of the numerical results of Remillieux et al. (2014).