NUMERICAL ALGORITHM OF SEISMIC ATTENUATION ESTIMATION IN ANISOTROPIC FRACTURED POROUS FLUID-SATURATED MEDIA

In our work we investigate the effect of transport and elastic properties anisotropy on seismic attenuation due to fracture-to-fracture wave-induced fluid flow using numerical algorithm of estimation of seismic wave attenuation in anisotropic fractured porous fluid-saturated media. Algorithm is based on numerical solution of anisotropic Biot equations using finite-difference scheme on staggered grid. We perform a set of numerical experiments to model wave propagation in fractured media with anisotropic fractured-filling material providing wave-induced fluid flow within interconnected fractures. Recorded signals are used for numerical estimation of inverse quality factor. Results demonstrate the effect of fracture-filling material anisotropy on seismic wave attenuation.

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Seismic wave attenuation and dispersion due to wave-induced fluid flow in rocks with strong permeability fluctuations

The Journal of the Acoustical Society of America ◽

10.1121/1.4824967 ◽

2013 ◽

Vol 134 (6) ◽

pp. 4742-4751 ◽

Cited By ~ 14

Author(s):

J. Germán Rubino ◽

Leonardo B. Monachesi ◽

Tobias M. Müller ◽

Luis Guarracino ◽

Klaus Holliger

Keyword(s):

Fluid Flow ◽

Seismic Wave ◽

Wave Attenuation ◽

Seismic Wave Attenuation ◽

Wave Induced ◽

Attenuation And Dispersion

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Pore fluid effects on S-wave attenuation caused by wave-induced fluid flow

Geophysics ◽

10.1190/geo2011-0233.1 ◽

2012 ◽

Vol 77 (3) ◽

pp. L13-L23 ◽

Cited By ~ 37

Author(s):

Beatriz Quintal ◽

Holger Steeb ◽

Marcel Frehner ◽

Stefan M. Schmalholz ◽

Erik H. Saenger

Keyword(s):

Fluid Flow ◽

Wave Attenuation ◽

Pore Space ◽

Seismic Attenuation ◽

P Wave ◽

S Wave ◽

Hydrocarbon Reservoir ◽

Saturated Media ◽

Water Saturated ◽

Wave Induced

We studied seismic attenuation of P- and S-waves caused by the physical mechanism of wave-induced fluid flow at the mesoscopic scale. Stress relaxation experiments were numerically simulated by solving Biot’s equations for consolidation of 2D poroelastic media with finite-element modeling. The experiments yielded time-dependent stress-strain relations that were used to calculate the complex moduli from which frequency-dependent attenuation was determined. Our model consisted of periodically distributed circular or elliptical heterogeneities with much lower porosity and permeability than the background media, which contained 80% of the total pore space of the media. This model can represent a hydrocarbon reservoir, where the porous background is fully saturated with oil or gas and the low-porosity regions are always saturated with water. Three different saturation scenarios were considered: oil-saturated (80% oil, 20% water), gas-saturated (80% gas, 20% water), and fully water-saturated media. Varying the dry bulk and shear moduli in the background and in the heterogeneities, a consistent tendency was observed in the relative behavior of the S-wave attenuation among the different saturation scenarios. First, in the gas-saturated media the S-wave attenuation was very low and much lower than in the oil-saturated or in the fully water-saturated media. Second, at low frequencies the S-wave attenuation was significantly higher in the oil-saturated media than in the fully water-saturated media. The P-wave attenuation exhibited a more variable relative behavior among the different saturation degrees. Based on the mechanism of wave-induced fluid flow and on our numerical results, we suggest that S-wave attenuation could be used as an indicator of fluid content in a reservoir. Additionally, we observed that impermeable barriers in the background can cause a significant increase in S-wave attenuation. This suggests that S-wave attenuation could also be an indicator of permeability changes in a reservoir due to, for example, fracturing operations.

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Seismic wave attenuation and dispersion resulting from wave-induced flow in porous rocks — A review

Geophysics ◽

10.1190/1.3463417 ◽

2010 ◽

Vol 75 (5) ◽

pp. 75A147-75A164 ◽

Cited By ~ 457

Author(s):

Tobias M. Müller ◽

Boris Gurevich ◽

Maxim Lebedev

Keyword(s):

Fluid Flow ◽

Velocity Dispersion ◽

Wave Attenuation ◽

Field Measurements ◽

Theoretical Models ◽

Seismic Attenuation ◽

P Wave ◽

Induced Flow ◽

Wave Induced ◽

Attenuation And Dispersion

One major cause of elastic wave attenuation in heterogeneous porous media is wave-induced flow of the pore fluid between heterogeneities of various scales. It is believed that for frequencies below [Formula: see text], the most important cause is the wave-induced flow between mesoscopic inhomogeneities, which are large compared with the typical individual pore size but small compared to the wavelength. Various laboratory experiments in some natural porous materials provide evidence for the presence of centimeter-scale mesoscopic heterogeneities. Laboratory and field measurements of seismic attenuation in fluid-saturated rocks provide indications of the role of the wave-induced flow. Signatures of wave-induced flow include the frequency and saturation dependence of P-wave attenuation and its associated velocity dispersion, frequency-dependent shear-wave splitting, and attenuation anisotropy. During the last four decades, numerous models for attenuation and velocity dispersion from wave-induced flow have been developed with varying degrees of rigor and complexity. These models can be categorized roughly into three groups ac-cording to their underlying theoretical framework. The first group of models is based on Biot’s theory of poroelasticity. The second group is based on elastodynamic theory where local fluid flow is incorporated through an additional hydrodynamic equation. Another group of models is derived using the theory of viscoelasticity. Though all models predict attenuation and velocity dispersion typical for a relaxation process, there exist differences that can be related to the type of disorder (periodic, random, space dimension) and to the way the local flow is incorporated. The differences manifest themselves in different asymptotic scaling laws for attenuation and in different expressions for characteristic frequencies. In recent years, some theoretical models of wave-induced fluid flow have been validated numerically, using finite-difference, finite-element, and reflectivity algorithms applied to Biot’s equations of poroelasticity. Application of theoretical models to real seismic data requires further studies using broadband laboratory and field measurements of attenuation and dispersion for different rocks as well as development of more robust methods for estimating dissipation attributes from field data.

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Numerical Algorithm of Seismic Wave Propagation and Seismic Attenuation Estimation in Anisotropic Fractured Porous Fluid-Saturated Media

10.1007/978-3-030-86653-2_32 ◽

2021 ◽

pp. 434-448

Author(s):

Mikhail Novikov ◽

Vadim Lisitsa ◽

Tatyana Khachkova ◽

Galina Reshetova ◽

Dmitry Vishnevsky

Keyword(s):

Wave Propagation ◽

Seismic Wave ◽

Numerical Algorithm ◽

Seismic Wave Propagation ◽

Seismic Attenuation ◽

Saturated Media ◽

Attenuation Estimation

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Seismic attenuation: Effects of pore fluids and frictional‐sliding

Geophysics ◽

10.1190/1.1441276 ◽

1982 ◽

Vol 47 (1) ◽

pp. 1-15 ◽

Cited By ~ 268

Author(s):

Kenneth W. Winkler ◽

Amos Nur

Keyword(s):

Fluid Flow ◽

Strain Amplitude ◽

Seismic Wave ◽

Wave Attenuation ◽

Velocity Ratio ◽

Seismic Attenuation ◽

P Wave ◽

Amplitude Dependence ◽

S Wave ◽

Frictional Sliding

Seismic wave attenuation in rocks was studied experimentally, with particular attention focused on frictional sliding and fluid flow mechanisms. Sandstone bars were resonated at frequencies from 500 to 9000 Hz, and the effects of confining pressure, pore pressure, degree of saturation, strain amplitude, and frequency were studied. Observed changes in attenuation and velocity with strain amplitude are interpreted as evidence for frictional sliding at grain contacts. Since this amplitude dependence disappears at strains and confining pressures typical of seismic wave propagation in the earth, we infer that frictional sliding is not a significant source of seismic attenuation in situ. Partial water saturation significantly increases the attenuation of both compressional (P) and shear (S) waves relative to that in dry rock, resulting in greater P‐wave than S‐wave attenuation. Complete saturation maximizes S‐wave attenuation but causes a reduction in P‐wave attenuation. These effects can be interpreted in terms of wave induced pore fluid flow. The ratio of compressional to shear attenuation is found to be a more sensitive and reliable indicator of partial gas saturation than is the corresponding velocity ratio. Potential applications may exist in exploration for natural gas and geothermal steam reservoirs.

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