A major cause of seismic attenuation in fluid-saturated rocks is the flow pore fluid induced by passing wave. At sonic and ultrasonic frequencies, appears to be dominated local (pore-scale) between pores different shapes orientations. simple squirt model developed which all parameters can independently measured or estimated from measurements. The space rock assumed consist stiff porosity compliant (or soft) present at grain contacts. effect isotropically distributed modeled considering...

SUMMARY We perform a theoretical study of the effect fine layering on compressional-wave velocities and attenuation coefficients in fluid-saturated rocks. This permeable rock differs from that purely elastic solid because local flow pore fluid across interfaces, which is caused by passing wave. For analytical calculations. Biot theory applied to non-homogeneous (randomly periodically layered) porous media leading Biot's equations with variable coefficients. By analysing these help...

Fractures in a porous rock can be modelled as very thin and highly layers background. First, dispersion equation for P wave propagating periodically layered poroelastic medium is obtained using propagator matrix approach applied to Biot equations of poroelasticity with periodic coefficients. Then the limit low stiffness thickness this yields an expression effective P-wave modulus fractured material. When both pores fractures are dry, material equivalent transversely isotropic elastic...

ABSTRACT Natural fractures in hydrocarbon reservoirs can cause significant seismic attenuation and dispersion due to wave induced fluid flow between pores fractures. We present two theoretical models explicitly based on the solution of Biot's equations poroelasticity. The first model considers as planes weakness (or highly compliant very thin layers) infinite extent. In second are modelled penny‐shaped voids finite radius. both is a result conversion incident compressional energy into...

Abstract In order to study the effect of micro‐CT scan resolution and size on accuracy upscaled digital rock property estimation core samples Bentheimer sandstone images with varying from 0.9 μm 24 are used. We statistically show that correlation length pore‐to‐matrix distribution can be reliably determined for finer than 9 voxels per representative volume this is about 15 3 length. Similar values also valid total porosity, specific surface area, mean curvature, topology pore space. Only...

Interface conditions at a boundary between two porous media are derived directly from Biot’s equations of poroelasticity by replacing the discontinuity surface with thin transition layer, in which properties medium change rapidly yet continuously, and then taking limit as thickness layer approaches zero. The interface obtained this way, well known “open-pore” conditions, shown to be only ones that fully consistent validity throughout poroelastic continuum, including surfaces across...

A detailed analysis of the relationship between elastic waves in inhomogeneous, porous media and effect wave-induced fluid flow is presented. Based on results poroelastic first-order statistical smoothing approximation applied to Biot’s equations poroelasticity, a model for wave attenuation dispersion due 3-D randomly inhomogeneous developed. Attenuation depend linear combinations spatial correlations fluctuating parameters. The observed frequency dependence typical relaxation phenomenon....

Maximizing the recovery of known hydrocarbon reserves is one biggest challenges facing petroleum industry today. Optimal production strategies require accurate monitoring production-induced changes reservoir saturation and pressure over life field. Time-lapse seismic technology increasingly used to map these in space time. However, until now, interpretation time-lapse data has been mostly qualitative. In order allow estimation saturation, it necessary know quantitative relationship between...

Mavko and Jizba propose a quantitative model for squirt dispersion of elastic-wave velocities between seismic ultrasonic frequencies in granular rocks. Their central results are the expressions so-called unrelaxed frame bulk shear moduli computed under an assumption that stiff pores drained (or dry) but soft filled with fluid. Mavko-Jizba limited to liquid-saturated rocks become inaccurate when fluid-bulk modulus is small (e.g., gas-saturated rocks). We have derived new fluid-saturated...

The squirt-flow wave attenuation mechanism is implemented in Biot’s theory of poroelasticity the form differential equations. All stiffnesses involved stress-strain relation become complex and frequency dependent, which can exactly be expressed terms kernels based on Zener mechanical model. In time domain, this approach implies convolutions, are circumvented by introducing memory variables. equations consistent with Gassmann’s Mavko-Jizba at low high frequencies, respectively. coefficients...

When a seismic wave travels through fluid-saturated porous reservoir containing aligned fractures, it induces oscillatory fluid flow between the fractures and embedding background medium. Although there are numerous theoretical models for quantifying associated attenuation velocity dispersion, they rely on certain assumptions, such as infinitesimal fracture thickness dilute concentration, which rarely hold in real reservoirs. The objective of this work is to overcome some these limitations...

ABSTRACT The detection and characterisation of domains intersecting fractures are important goals in several disciplines current interest, including exploration production unconventional reservoirs, nuclear waste storage, CO 2 sequestration, groundwater hydrology, among others. objective this study is to propose a theoretical framework for quantifying the effects fracture intersections on frequency‐dependent elastic properties fluid‐saturated porous fractured rocks. Three characteristic...

Distributed acoustic sensing (DAS) is a rapidly developing technology particularly useful for the acquisition of vertical seismic profile (VSP) surveys. DAS data are increasingly used imaging, but not estimating rock properties. We have developed workflow elastic properties subsurface using full-waveform inversion (FWI) VSP data. Whereas conventional borehole geophones usually measure three components particle velocity, measures single quantity, which an approximation strain or rate along...

Porous rocks encountered in hydrocarbon reservoirs are often saturated with a mixture of two or more fluids. Generation synthetic seismograms as well interpretation in-situ attenuation measurements require theoretical understanding the relation between heterogeneous distribution fluid patches and acoustic properties rocks. Thus, problem calculating fluids has attracted considerable interest (White, 1975; Murphy, 1982; Gist, 1994; Mavko Mukerji, 1998; Pride et al., 2004). At same time, this...

Scattering caused by fine layering is known to play an important role in seismic attenuation. If the rock also porous and permeable, additional attenuation can be a flow of pore fluid induced passing wave (see e.g., White, 1983). At frequencies higher than 100 kHz, standard Biot's (Biot, 1962; Bourbié et al., 1987) may contribute overall layered poroelastic rock. While has been well for decades, effects scattering interlayer have studied extensively both theoretically numerically recent...

ABSTRACT Saturation of porous rocks with a mixture two fluids has substantial effect on seismic‐wave propagation. In particular, partial saturation causes significant attenuation and dispersion the propagating waves due to mechanism wave‐induced fluid‐flow. Such flow arises when passing wave induces different fluid pressures in regions rock saturated by fluids. Most models mesoscopic heterogeneities imply that are distributed regular way. However, recent experimental studies show have less...

We simulate the effect of fractures by considering them to be thin circular cracks in a poroelastic background. Using solution scattering problem for single‐crack and multiple‐scattering theory, we estimate attenuation dispersion elastic waves porous medium containing sparse distribution cracks. When comparing with similar model, which effects are neglected, find that there is agreement at high frequencies discrepancies low frequencies. conclude interaction between should not neglected...

One of the main causes azimuthal anisotropy in sedimentary rocks is tectonic stresses earth’s crust. We have developed an analytic model for seismic caused by application a small anisotropic stress. first considered isotropic linearly elastic medium (porous or nonporous) permeated distribution discontinuities with random (isotropic) orientation (such as randomly oriented compliant grain contacts cracks). The geometry individual not specified. Instead, their behavior defined ratio B normal to...

ABSTRACT Naturally fractured reservoirs are becoming increasingly important for oil and gas exploration in many areas of the world. Because fractures may control permeability a reservoir, it is to be able find characterize zones. In reservoirs, wave‐induced fluid flow between pores can cause significant dispersion attenuation seismic waves. For waves propagating normal fractures, this effect has been quantified earlier studies. Here we extend incidence results oblique using known expressions...

Laboratory measurements of elastic and anelastic parameters dry water-saturated sandstones with low (0.7- 1.1-mD) high (425-mD) permeability have been conducted at seismic frequencies (0.1 to 120 Hz). The experiments were performed a laboratory apparatus that measures the stress-strain relationship in linear regime. extensional attenuation low-permeability exhibits prominent peaks band, accompanied by considerable dispersion. Variations dispersion high-permeability sandstone are below...