The models consist of hundreds of representative elementary volumes revs, where the rev is partially saturated with water and gas pockets. The new theory extends the classic biots poroelastic wave theory to include the effects of cracks. The existence of three dilatational waves is explained through three scalar potentials satisfying wave equations. A numerical analysis shows that all models can have an effect over the exploration seismic frequency range. Carcione2, and weitao sun3 abstract understanding acoustic wave dispersion and. Field measurements and transfer function analysis st. Earthquakes generate four principal types of elastic waves. The emphasis is on the propagation of seismic waves in. Elastic wave propagation and attenuation in porous rock layers with. Illingworth, who have done much to shape my ideas on seismic wave propagation, for their help and criticism. The effect of fluid viscosity on seismicwave attenuation and velocity is. Seismic wave propagation in inhomogeneous and anisotropic. Read seismic reflection from an interface between an elastic solid and a fractured porous medium with partial saturation, transport in porous media on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
This gives rise to systematic variations in the induced attenuation as a function of the materials properties, the relative geometries of the recording array, and the fractured medium. It is commonly accepted that the presence of cracks in subsurface rocks plays an important role in seismic wave propagation. The attenuation of p wave in a periodic layered porous media containing cracks. Analysis of pwave attenuation anisotropy in fractured. To explore these effects, we developed an effective medium model that describes the p wave dispersion and attenuation in inhomogeneous porous media containing a distribution of aligned cracks. It distills a vast quantity of background theory and laboratory results into a series of concise chapters that provide practical solutions to problems in geophysical data interpretation. Azimuthal attenuation elastic impedance inversion for.
Reflection and transmission of elastic waves by a fluid. Wave induced fluid flow due to mesoscopic heterogeneity can explain seismic dispersion and attenuation in the seismic frequency band. Modeling wave propagation in cracked porous media with. Fluid flow may be on either a wavelength scale or a local scale depending on the model and whether the cracks are aligned or randomly oriented, resulting in completely different effects on seismic wave propagation. We establish a patchy saturation model and derive the seismic wave equations for patchy saturated porous media on the basis of biots equations and johnsons bulk modulus. Wave propagation in anisotropic, anelastic, porous and electromagnetic media volume 38 handbook of geophysical exploration. Seismic waves can be generated by a sudden release of energy such as an earthquake. Seismic wave propagation in cracked porous media eap british. By referring this study, in direct pore measurement method based on seismic wave propagation can be developed. This interaction has been described by biot in his theory of poroelasticity. Wave propagation in anisotropic, anelastic, porous and electromagnetic media examines the differences between an ideal and a real description of wave propagation, starting with the introduction of relevant stressstrain relations. In layered media, propagation of the seismic wave gives rise to a secondorder effect.
Several wave propagation numerical experiments were performed to estimate the attenuation of seismic wave in fractured porous fluidfilled media and influence of fracture connectivity on attenuation and dispersion. Elastic wave propagation in fractured media using the discontinuous galerkin method jonas d. This study describes a unified elastic wave theory for porous rock media containing cracks. The mesoscopic heterogeneity mainly contains lithological variations, patchy saturation and mesoscopic fractures. Reflection and transmission coefficients of compressional and shear waves propagating in such system are calculated. In addition to the scattering, wiff process is another factor that affects the stress wave transmission. The wave propagation in cracked media is solved by means of 2d dynamic boundary integral equation. Seismic wave parameter plays very important role to characterize reservoir properties whereas pore parameter is one of the most important parameter of reservoir. Request pdf seismic wave propagation in cracked porous media the movement of interstitial fluids within a cracked solid can have a significant effect on the properties of seismic waves of long. Abstractunderstanding acoustic wave dispersion and attenuation induced by local squirt fluid flow between pores and cracks compliant. School of geosciences, china university of petroleum, qingdao 266580, china. Carcione2, and weitao sun3 abstract understanding acoustic wave dispersion and attenuation induced by local squirt fluid flow between pores and cracks compliant pores is fundamental for better characterization of the porous rocks.
Because modeling wave propagation in 3d inelastic media with exact finite difference techniques is slow and difficult to implement, we apply a technique using born scattering theory, and our application is a unique and new implementation that allows us to examine the influence of. Allan haas, phd principal engineering geophysicist. Seismic attenuation and dispersion in a cracked porous. We solve the equations, obtain the attenuation coefficients, and analyze the characteristics of wave attenuation in the seismic frequency range. Seismic wave propagation in cracked porous media pointer. Influence of patchy saturation on seismic dispersion and. In multilayer porous media, traveling seismic wave gives rise to a second type of seismoelectric response. At local scales, nonlinear extensions of standard elastodynamic equations have been suggested to better describe wave propagation in complex porous media. In principle, the pattern of seismic attenuation recorded on an array of sensors contains information about the medium, in terms of material heterogeneity and anisotropy, as well as material properties such as. Postgraduate student, moscow state university, physical department, moscow, russia.
In this thesis, i use the seismic modelling approach to study the effects of attenuation anisotropy in fractured porous media using p waves with the main aim of improving the understanding of these effects and exploring the physical basis of using attenuation anisotropy as a potential tool for the characterization of fractured reservoirs. Seismic wave, vibration generated by an earthquake, explosion, or similar energetic source and propagated within the earth or along its surface. Wave propagation in fractured porous media plane waves, impulse seismograms, point source in anisotropic randomly inhomogeneous porous media forward and inverse problems of fractured porous media. Modeling wave propagation in cracked porous media with pennyshaped inclusions lin zhang 1, jing ba, jose m. They have served as rigorous and formal foundations to study acoustic wave propagation in saturated porous media.
Simulating propagation of separated wave modes in general anisotropic media, part i. This phenomenon significantly affects the propagation of elastic waves in earth. Seismic wave propagation in patchysaturated porous media is studied by numerical simulation in time domain at the seismic frequency band 1 hz. Modeling wave propagation in cracked porous media with penny. A 2d bem program is developed to model the elastic waves excited by a point explosive source. Theory of compressional and transverse wave propagation in. The seismoelectric method is a relatively new geophysical technique consisting in measuring electromagnetic signals associated with the propagation of seismic waves in porous media.
Study of fluidflow effects on seismic propagation in fractured porous media. E ective models for seismic wave propagation in porous media. Cambridge core solid earth geophysics the rock physics handbook by gary mavko. Attenuation of p waves in a porous medium containing various cracks. The coupled seismoelectric wave propagation in porous media. Seismic wave attenuation in fluidsaturated porous media. Seismic attenuation in fluidsaturated porous rocks can occur by geometric spreading, wave scattering or the internal dissipation of energy, most likely due to the squirtflow mechanism. Attenuation of waves in geologic formations is of importance in seismic studies at very low frequencies 1100 hz.
The patchy saturation models which are locally based on biot theory for porous media have been deeply studied, but the. Among the various mechanisms related to attenuation and dispersion, the biot and squirt. Seismic modelling study of pwave attenuation and velocity. Mechanical and hydraulic properties of a crack can significantly affect seismic wave propagation. Pdf seismic waves in fractured porous media researchgate. Our results demonstrate that, in fluidsaturated porous rocks, fluid mobility greatly influences seismic wave propagation. Seismic wave propagation in cracked porous media pointer 2000. Consequently, the resulting equations are obtained from the momentum balance equations. In each case the cracks may be aligned or randomly oriented, leading, respectively, to anisotropic or isotropic wave speeds and attenuation factors. We consider three distinct mechanisms of waveinduced fluid flow. Seismic waves can be generated by a sudden release of energy such as an earthquake, volcanic eruption, or chemical explosion. Seismic wave propagation in cracked porous media geophysical. Biot theory describes wave propagation in a porous saturated medium, i. Seismic reflection from an interface between an elastic.
A seismic wave is a mechanical disturbance or energy packet that can propagate from point to point in the earth. In principle, the pattern of seismic attenuation recorded on an array of sensors contains information about the medium, in terms of material heterogeneity and anisotropy, as. In general, seismic velocities exhibit behaviour that is intermediate between that of empty cracks and that of isolated liquid. The purpose of this paper is to mathematically model seismic wave propagation in saturated fractured porous media when the wavelength is large compared.
Use features like bookmarks, note taking and highlighting while reading wave fields in real media. Jun 21, 2012 seismic wave parameter plays very important role to characterize reservoir properties whereas pore parameter is one of the most important parameter of reservoir. Summary the movement of interstitial fluids within a cracked solid can have a significant effect on the properties of seismic waves of long. School of geosciences, china university of petroleum, qingdao 266555, china. Simulation of seismic wave propagation in poroelastic. Seismic wave simulation using biots formulations is computationally expensive when compared with the acoustic and elastic. The rock physics handbook addresses the relationships between geophysical observations and the underlying physical properties of rocks. Rocks in earths crust usually contain both pores and cracks. Seismic models of reflections from attenuating layers. Finite difference based wave simulation in fractured porous.
Seismic wave propagation in cracked porous media request pdf. Surface waves and guided waves, and their propagation in porous media are of increasing interest for a variety of fields, notably in onshore and offshore civil engineering as well as in borehole logging. Luyben, voorzitter van het college voor promoties, in het openbaar te verdedigen op maandag 2 mei 2016 om 10. The wave numerical simulation of discontinuous galerkin finite element method dgfet for elastic wave equation is an effective tool to model wave propagation in the fractured porous media. Kennett title page contents jj ii j i page 3 of 497 back full screen close quit rs s e anu 2 coupled equations for seismic waves 46 2. When the downgoing seismic wave traverses an interface between two porous media having contrast in mechanical andor electrical properties a timevarying charge. Apr 10, 2010 read seismic reflection from an interface between an elastic solid and a fractured porous medium with partial saturation, transport in porous media on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. By referring this study, in direct pore measurement method based on seismic wave propagation can be. Numerical analysis of seismic wave propagation in fluidsaturated. Seismic velocities in dry and saturated cracked solids. This study solves the mathematical model for the propagation of harmonic plane waves in a dissipative double porosity solid saturated by a viscous fluid. Velocities of these waves are obtained from the roots of a cubic equation. Theory of compressional and transverse wave propagation in consolidated porous media.
The purpose of this paper is to mathematically model seismic wave propagation in saturated fractured porous media when the wavelength is large compared to the fracture characteristic length. Effective models for seismic wave propagation in porous media. Fractured poroelastic media show significant attenuation and velocity dispersion due to this mechanism. Biot 1956a, b ignores the microscopic level and assumes that continuum mechanics can be applied to measurable macroscopic quantities. A unified theory for elastic wave propagation through porous media. One of the rst models to account for mesoscopicscale inclusions in porous me dia are the ones of white et al. Seismic wave propagation in nonlinear viscoelastic media. A lot of studies have been done on seismic wave attenuation and dispersion theory at different scales.
Wave propagation through porous media allows us to understand the response and interaction that occur between the elastic rock matrix and the fluid. Qiyu han who has been working on wave propagation in porous and cracked. Simulation of surface waves in porous media geophysical. Since substantial inhomogeneities in fluid permeability of porous geological materials are to be expected, the regions of highest local permeability contribute most to the wave energy dissipation while. Fracture detection using p wave data and a seismic study.
Now in its second edition, major new chapters are presented on statistical rock physics and velocityporosityclay models for clastic sediments. In this study, we use the volume averaging technique to investigate the wave propagation in fractured porous media saturated by two immiscible fluids based. To explore these effects, we developed an effective medium model that describes the pwave dispersion and attenuation in inhomogeneous porous media containing a distribution of aligned cracks. For all cases, both seismic wave velocities decrease with increasing crack density. Azimuthal attenuation elastic impedance inversion for fluid. Therefore, wave propagation phenomena in pore media is important to be studied. A unified theory for elastic wave propagation through porous. The patchy saturation models which are locally based on biot theory for porous media have been deeply studied, but the patchy saturation model for. Finite difference based wave simulation in fractured. Coupled seismoelectric wave propagation in porous media. It is another reason why using nonlinear stressstrain relations is interesting in seismic wave propagation modelling.
Seismic velocities in dry and saturated cracked solids o. Mechanics of deformation and acoustic propagation in porous media. Seismic wave propagation modeling in porous media for various. Pdf a fractured porous medium is a dualporosity medium, i. Many seismic applications require sources and receivers to be placed at or near interfaces. Seismic wave propagation in cracked porous media nasaads. It consists of energy loss due to pwave conversion to biot diffusive modes at mesoscopicscale inhomogeneities. Attenuation of p waves in a porous medium containing various. Wave propagation in anisotropic, anelastic, porous. This crack density parameter can be related quantitatively to crack traces observed in thin section.
Direct numerical simulations for wave propagation in highly heterogeneous fractured media can be computationally expensive and require some type of model reduction. Results for completely dry or saturated cracks, for mixtures of dry and saturated cracks, and for cracks saturated with a compressible fluid are presented. Propagation and attenuation of elastic waves in a double. Waveinduced fluid flow generates a dominant attenuation mechanism in porous media. Seismic wave velocity attenuation and dispersion in the. A fractured porous medium is a dualporosity medium, i.
The effects of fracture permeability on acoustic wave. Based on the modified linearslip theory and anisotropic gassmanns equation, we derive an analytical expression for a linearized pp wave reflection coefficient and an azimuthal attenuation elastic impedance. The rock physics handbook by gary mavko cambridge core. Seismic reflection from an interface between an elastic solid. Elastic wave propagation in fractured media using the. Summary seismic wave attenuation and dispersion are caused by the interaction of rock skeleton and pore fluid properties in fluidcontaining porous media. Seismic modelling experiments are implemented in a. May 24, 2002 fluid flow may be on either a wavelength scale or a local scale depending on the model and whether the cracks are aligned or randomly oriented, resulting in completely different effects on seismic wave propagation.
Numerical simulation results and theoretical predictions both. Contrary to the traditional view, seismic attenuation in biots theory of fluidsaturated porous media is due to viscous damping of local not global porefluid motion. In this report, we adopt an equivalent model qizhen et al. The attenuation of p wave in a periodic layered porous media. Other new and expanded topics include anisotropic seismic signatures, borehole waves, models for fractured media, poroelastic models, and attenuation models. Propagation and attenuation of pwaves in patchy saturated. The movement of interstitial fluids within a cracked solid can have a significant effect on the properties of seismic waves of long wavelength propagating through the solid. Seismic attenuation and dispersion in a cracked porous medium. This is why many models for seismic wave propagation in porous media with mesoscopicscale heterogeneities assume a periodic distribution of inclusions.