Acoustic characterization of fracture permeability at Chalk River, Ontario

1983 ◽  
Vol 20 (3) ◽  
pp. 468-476 ◽  
Author(s):  
Frederick L. Paillet
Keyword(s):  
Wave Amplitude ◽  
Acoustic Analysis ◽  
Wave Attenuation ◽  
Close Correlation ◽  
Wave Mode ◽  
Acoustic Energy ◽  
Shear Mode ◽  
Fracture Permeability ◽  
Keywords Fracture ◽  
Tube Wave

This study was undertaken to test recently formulated acoustic-analysis methods for fracture interpretation. The study area was selected because surface outcrops of igneous and metamorphic rocks have numerous, interconnected fractures and major lithology changes. In-situ acoustic-refraction data were obtained by digitally recording the entire pressure signal received by a conventional acoustic borehole logging system. The acoustic energy source had a centerband frequency of 34 kHz, and data were obtained at 60 and 90 cm source/receiver spacing. Borehole geometry produces waveforms with strong shear arrivals and high amplitudes associated with the fundamental guided fluid mode known as the tube wave. Waveforms refracted across fractures that are open on the borehole have shear mode excitation and tube-wave attenuation effects similar to previously described effects for isolated fractures in very uniform lithologies. Independent permeability data for the Chalk River boreholes are available in the form of effective-fracture apertures determined by straddle packer isolation and injection tests. The best correlation between the permeabilities measured by packer tests and acoustic data is obtained by integrating the difference between local tube-wave amplitude and an average amplitude from many adjacent stations. This synthetic amplitude-deficit log shows close correlation with zones of large measured permeabilities; however, there are some quantitative differences. These are attributed to: (1) differing radii of investigation, (2) effects of fracture interconnectivity, and (3) drilling damage in highly weathered and fractured zones. The tube-wave-amplitude method also does not seem applicable to depths less than about 50 m where the tube-wave mode is relatively unexcited. Keywords: fracture permeability, borehole acoustics, fracture hydrology.

Physical modeling of the full acoustic waveform in a fractured, fluid‐filled borehole

Geophysics ◽  
1988 ◽  
Vol 53 (9) ◽  
pp. 1219-1224
Author(s):  
Petko Zlatev ◽  
Eileen Poeter ◽  
Jerry Higgins
Keyword(s):  
Exponential Function ◽  
Physical Modeling ◽  
Wave Amplitude ◽  
Crystalline Rock ◽  
Wave Mode ◽  
Fracture Aperture ◽  
Negative Exponential Function ◽  
Tube Wave ◽  
Fracture Apertures ◽  
Negative Exponential

Three concrete models were constructed, one each with a fracture oriented at 90, 45, and 10 degrees to the axis of the borehole. These were used to simulate physically the propagation of the full acoustic waveform through a fluid‐filled borehole in crystalline rock and to ascertain the effects of fracture aperture and orientation of fluid‐filled fractures on the waveform. The tube‐wave mode of the waveform was most indicative of the magnitude of fracture aperture. Normalized tube‐wave amplitude decreased as a negative exponential function of aperture over the range of fracture apertures studied (closed to 0.66 cm). The 90 degree fracture orientation caused greater tube‐wave amplitude reduction than the 45 degree fracture. We hypothesize that this reduction can be attributed to the borehole wall’s guiding the wave across the 45 degree fracture. However, the 10 degree model gave ambiguous results, which are believed to be related to the low ratio of tube‐wave wavelength to aperture as measured parallel to the borehole axis, i.e., axial aperture.

A hybrid wave-mode formulation for the vibro-acoustic analysis of 2D periodic structures

2016 ◽  
Vol 363 ◽  
pp. 285-302 ◽  
Author(s):  
C. Droz ◽  
C. Zhou ◽  
M.N. Ichchou ◽  
J.-P. Lainé
Keyword(s):  
Acoustic Analysis ◽  
Periodic Structures ◽  
Wave Mode ◽  
Hybrid Wave

Ultrasonic SHM Approach to Predict Delamination in a Laminated Beam Using d15 Piezoelectric Sensors

2021 ◽  
pp. 1-32
Author(s):  
Hussain Altammar ◽  
Nathan Salowitz
Keyword(s):  
Lead Zirconate Titanate ◽  
Critical Factor ◽  
Lead Zirconate ◽  
Wave Mode ◽  
Ultrasonic Waves ◽  
Propagation Path ◽  
Shear Mode ◽  
Novel Approach ◽  
Viable Approach ◽  
Laminated Structures

Abstract Ultrasonic structural health monitoring (SHM), employing embedded piezoelectric elements to actuate and sense ultrasonic waves, has greatly advanced in recent years. This paper presents a novel approach to address the prevailing challenges in the inspection of laminated structures for delamination using shear-mode (d15) piezoelectric transducers, composed of lead zirconate titanate (PZT). To experimentally evaluate the effectiveness of the proposed approach, a beam-like laminated specimen consisting of internally embedded d15 square PZTs was fabricated with simulated delamination at the interface of an adhesive joint. Evaluation of the results showed that the location of shear-mode actuators is a critical factor to detect delamination and to predict the propagation path of delamination. Delamination initiated close to actuators are more likely to be detected owing to their remarkable sensitivity of structural stiffness surrounding their region. The antisymmetric A0 wave mode generated by these actuators exhibit high interaction with damage, suggesting internally embedded d15 PZTs are a viable approach that can potentially advance the inspection tools of ultrasonic SHM.

Stoneley‐wave attenuation and dispersion in permeable formations

Geophysics ◽  
1989 ◽  
Vol 54 (3) ◽  
pp. 330-341 ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
Dispersion Relation ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Water Infiltration ◽  
Stoneley Wave ◽  
Biot Theory ◽  
Static Approximation ◽  
Quasi Static Approximation ◽  
Tube Wave ◽  
Dynamic Description

The tube wave, or low‐frequency manifestation of the Stoneley wave, has been modeled previously using the quasi‐static approximation; I extend this method to include the effect of the formation matrix compressibility, which tends to marginally increase the tube‐wave attenuation. Using the Biot theory of poroelasticity, I develop a fully dynamic description of the Stoneley wave. The dispersion relation derived from Biot’s equations reduces in the low‐frequency limit to the quasi‐static dispersion relation. Comparisons of the quasi‐static and dynamic theories for typical sandstones indicate the former to be a good approximation to at least 1 kHz for oil and water infiltration. At higher frequencies, usually between 5 and 20 kHz for the formations considered, a maximum in the Stoneley Q is predicted by the dynamic theory. This phenomenon cannot be explained by the quasi‐static approximation, which predicts a constantly increasing Q with frequency. Instead, the peak in Q may be understood as a transition from dispersion dominated by bore curvature to a higher frequency regime in which the Stoneley wave behaves like a wave on a flat fluid‐porous interface. This hypothesis is supported by analytical and numerical results.

Discussion of “Characteristics of an Open Tube Wave Attenuation System”

1969 ◽  
Vol 95 (3) ◽  
pp. 430-436
Author(s):  
T. Milne Dick ◽  
Wyndham J. Roberts ◽  
A. O. Ofuya
Keyword(s):  
Wave Attenuation ◽  
Open Tube ◽  
Tube Wave

Stability analysis for the onset of thermoacoustic oscillations in a gas-filled looped tube

2014 ◽  
Vol 741 ◽  
pp. 585-618 ◽  
Author(s):  
H. Hyodo ◽  
N. Sugimoto
Keyword(s):  
Wave Equation ◽  
Stability Analysis ◽  
Temperature Gradient ◽  
Energy Flux ◽  
Diffusion Layer ◽  
Wave Mode ◽  
Frequency Equation ◽  
Acoustic Energy ◽  
Tube Length ◽  
Thermoacoustic Oscillations

AbstractThis paper develops a stability analysis for the onset of thermoacoustic oscillations in a gas-filled looped tube with a stack inserted, subject to a temperature gradient. Analysis is carried out based on approximate theories for a thermoviscous diffusion layer derived from the thermoacoustic-wave equation taking account of the temperature dependence of the viscosity and the heat conductivity. Assuming that the stack consists of many pores axially and that the thickness of the diffusion layer is much thicker than the pore radius, the diffusion wave equation with higher-order terms included is applied for the gas in the pores of the stack. For the gas outside of the pores, the theory of a thin diffusion layer is applied. In a section called the buffer tube over which the temperature relaxes from that at the hot end of the stack to room temperature, the effects of the temperature gradient are taken into account. With plausible temperature distributions specified on the walls of the stack and the buffer tube, the solutions to the equations in both theories are obtained and a frequency equation is finally derived analytically by matching the conditions at the junctions between the various sections. Seeking a real solution to the frequency equation, marginal conditions of instability are obtained numerically not only for the one-wave mode but also for the two-wave mode, where the tube length corresponds to one wavelength and two wavelengths, respectively. It is revealed that the marginal conditions depend not only on the thickness of the diffusion layer but also on the porosity of the stack. Although the toroidal geometry allows waves to be propagated in both senses along the tube, it is found that the wave propagating in the sense from the cold to the hot end through the stack is always greater, so that a travelling wave in this sense emerges as a whole. The spatial and temporal variations of excess pressure and mean axial velocity averaged over the cross-section of a flow passage are displayed for the two modes of oscillations at the marginal state. The spatial distribution of mean acoustic energy flux (acoustic intensity) over one period is also shown. It is unveiled that the energy flux is generated only in the stack, and it decays slowly in the other sections by lossy effects due to a boundary layer. Mechanisms for the generation of the acoustic energy flux are also discussed.

The Research on the Model for Calculating Relative Acoustical Amplitude on Interface I Based on Attenuation Theory of Acoustic Wave

2012 ◽  
Vol 229-231 ◽  
pp. 2638-2642
Author(s):  
Chi Ai ◽  
Xiang Meng ◽  
Ming Hao ◽  
Wan Chun Zhao ◽  
Hui Zhi Zhao
Keyword(s):  
Energy Consumption ◽  
Acoustic Wave ◽  
Wave Amplitude ◽  
Wave Attenuation ◽  
Influence Factors ◽  
Propagation Path

Acoustic wave can cause particle vibration in the process of transmission and the energy consumption gradually, and the acoustic wave amplitude will attenuation. Through analysising the propagation path of acoustic wave in the layer media in the process of well cementation., according to the theory of acoustic wave attenuation, the model for calculating the relative acoustical amplitude of well cementation on interfaceⅠ. And on this basis, to discuss the influence factors of relative acoustic on interfaceⅠ

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