Theoretical investigation of Stoneley-wave attenuation and dispersion in a fluid filled fracture in transversely isotropic formation

ARI ◽  
1999 ◽  
Vol 51 (4) ◽  
pp. 254-257 ◽  
Author(s):  
A. S. Ashour
Keyword(s):  
Theoretical Investigation ◽  
Wave Attenuation ◽  
Transversely Isotropic ◽  
Stoneley Wave ◽  
Attenuation And Dispersion

Stoneley wave attenuation and dispersion and the dynamic permeability correction

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. WA1-WA10 ◽  
Author(s):  
Xiumei Zhang ◽  
Tobias M. Müller
Keyword(s):  
Hybrid Model ◽  
Wave Attenuation ◽  
Stoneley Wave ◽  
Relaxation Length ◽  
Permeability Model ◽  
P Waves ◽  
Stoneley Waves ◽  
Dynamic Permeability ◽  
Viscous Relaxation ◽  
Attenuation And Dispersion

Stoneley waves induce fluid pressure gradients in a permeable formation surrounding the borehole. These gradients are equilibrated through pressure diffusion, that is to say, slow P-waves in the context of Biot’s poroelasticity theory. Because slow P-waves are strongly sensitive to the formation permeability, the Stoneley-slow P-wave interaction can be used to retrieve the formation permeability from the attenuation and dispersion of Stoneley waves. The accuracy of this established technique in high-permeability formations deteriorates when slow P-waves are not pure diffusion waves; hence, the permeability dependence is more complicated. This effect on Stoneley waves is captured by applying the Johnson-Koplik-Dashen dynamic permeability model. Their model depends on a viscous relaxation length. However, in the estimation of formation permeability from Stoneley waves, this parameter is typically not measured but is estimated from an empirical equation, wherein material properties and microstructural descriptors are lumped together. When the so-calculated relaxation length is erroneous, the inverted formation permeability from the Stoneley wave is not correct either. To overcome this limitation and to provide a versatile alternative, the dynamic permeability problem is reformulated within the viscosity-extended Biot framework. Its physical basis is the conversion scattering in random media from slow P- to slow S-waves. The correlation length of this so-called stochastic dynamic permeability model can be derived from pore-scale images, and it also captures the effect of pore interface roughness. This model is then combined with the simplified Biot-Rosenbaum model to predict Stoneley wave attenuation and dispersion. We have applied this hybrid model to interpret laboratory measurements for which the previously suggested choice of the viscous relaxation length does not provide an accurate prediction. The results indicate that the hybrid model can provide another approach to model Stoneley wave attenuation and dispersion across the entire frequency range.

The transversely isotropic poroelastic wave equation including the Biot and the squirt mechanisms: Theory and application

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 309-318 ◽  
Author(s):  
Jorge O. Parra
Keyword(s):  
Wave Equation ◽  
Fluid Flow ◽  
Analytical Solution ◽  
Seismic Waves ◽  
Transversely Isotropic ◽  
P Wave ◽  
Fluid Properties ◽  
Permeability Anisotropy ◽  
Attenuation And Dispersion ◽  
Maximum Permeability

The transversely isotropic poroelastic wave equation can be formulated to include the Biot and the squirt‐flow mechanisms to yield a new analytical solution in terms of the elements of the squirt‐flow tensor. The new model gives estimates of the vertical and the horizontal permeabilities, as well as other measurable rock and fluid properties. In particular, the model estimates phase velocity and attenuation of waves traveling at different angles of incidence with respect to the principal axis of anisotropy. The attenuation and dispersion of the fast quasi P‐wave and the quasi SV‐wave are related to the vertical and the horizontal permeabilities. Modeling suggests that the attenuation of both the quasi P‐wave and quasi SV‐wave depend on the direction of permeability. For frequencies from 500 to 4500 Hz, the quasi P‐wave attenuation will be of maximum permeability. To test the theory, interwell seismic waveforms, well logs, and hydraulic conductivity measurements (recorded in the fluvial Gypsy sandstone reservoir, Oklahoma) provide the material and fluid property parameters. For example, the analysis of petrophysical data suggests that the vertical permeability (1 md) is affected by the presence of mudstone and siltstone bodies, which are barriers to vertical fluid movement, and the horizontal permeability (1640 md) is controlled by cross‐bedded and planar‐laminated sandstones. The theoretical dispersion curves based on measurable rock and fluid properties, and the phase velocity curve obtained from seismic signatures, give the ingredients to evaluate the model. Theoretical predictions show the influence of the permeability anisotropy on the dispersion of seismic waves. These dispersion values derived from interwell seismic signatures are consistent with the theoretical model and with the direction of propagation of the seismic waves that travel parallel to the maximum permeability. This analysis with the new analytical solution is the first step toward a quantitative evaluation of the preferential directions of fluid flow in reservoir formation containing hydrocarbons. The results of the present work may lead to the development of algorithms to extract the permeability anisotropy from attenuation and dispersion data (derived from sonic logs and crosswell seismics) to map the fluid flow distribution in a reservoir.

Seismic wave attenuation due to fluid pressure diffusion at the mesoscopic scale: an experimental and numerical study

2021 ◽  
Author(s):  
Samuel Chapman ◽  
Jan V. M. Borgomano ◽  
Beatriz Quintal ◽  
Sally M. Benson ◽  
Jerome Fortin
Keyword(s):  
Seismic Wave ◽  
Seismic Waves ◽  
Wave Attenuation ◽  
Fluid Pressure ◽  
Fluid Distribution ◽  
Mesoscopic Scale ◽  
Seismic Wave Attenuation ◽  
X Ray ◽  
Pressure Diffusion ◽  
Attenuation And Dispersion

<p>Monitoring of the subsurface with seismic methods can be improved by better understanding the attenuation of seismic waves due to fluid pressure diffusion (FPD). In porous rocks saturated with multiple fluid phases the attenuation of seismic waves by FPD is sensitive to the mesoscopic scale distribution of the respective fluids. The relationship between fluid distribution and seismic wave attenuation could be used, for example, to assess the effectiveness of residual trapping of carbon dioxide (CO2) in the subsurface. Determining such relationships requires validating models of FPD with accurate laboratory measurements of seismic wave attenuation and modulus dispersion over a broad frequency range, and, in addition, characterising the fluid distribution during experiments. To address this challenge, experiments were performed on a Berea sandstone sample in which the exsolution of CO2 from water in the pore space of the sample was induced by a reduction in pore pressure. The fluid distribution was determined with X-ray computed tomography (CT) in a first set of experiments. The CO2 exosolved predominantly near the outlet, resulting in a heterogeneous fluid distribution along the sample length. In a second set of experiments, at similar pressure and temperature conditions, the forced oscillation method was used to measure the attenuation and modulus dispersion in the partially saturated sample over a broad frequency range (0.1 - 1000 Hz). Significant P-wave attenuation and dispersion was observed, while S-wave attenuation and dispersion were negligible. These observations suggest that the dominant mechanism of attenuation and dispersion was FPD. The attenuation and dispersion by FPD was subsequently modelled by solving Biot’s quasi-static equations of poroelasticity with the finite element method. The fluid saturation distribution determined from the X-ray CT was used in combination with a Reuss average to define a single phase effective fluid bulk modulus. The numerical solutions agree well with the attenuation and modulus dispersion measured in the laboratory, supporting the interpretation that attenuation and dispersion was due to FPD occurring in the heterogenous distribution of the coexisting fluids. The numerical simulations have the advantage that the models can easily be improved by including sub-core scale porosity and permeability distributions, which can also be determined using X-ray CT. In the future this could allow for conducting experiments on heterogenous samples.</p>

The influence of mesoscopic flow on the P-wave attenuation and dispersion in a porous media permeated by aligned fractures

2013 ◽  
Vol 57 (3) ◽  
pp. 482-506 ◽  
Author(s):  
Jixin Deng ◽  
Shangxu Wang ◽  
Gengyang Tang ◽  
Jianguo Zhao ◽  
Xiangyang Li
Keyword(s):  
Porous Media ◽  
Wave Attenuation ◽  
P Wave ◽  
Attenuation And Dispersion

scholarly journals A model forP-wave attenuation and dispersion in a porous medium permeated by aligned fractures

2005 ◽  
Vol 163 (1) ◽  
pp. 372-384 ◽  
Author(s):  
Miroslav Brajanovski ◽  
Boris Gurevich ◽  
Michael Schoenberg
Keyword(s):  
Porous Medium ◽  
Wave Attenuation ◽  
Attenuation And Dispersion

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.

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