The effect of fracture filling fluids on shear‐wave propagation

Guest, Sean; Kolk, Cees van der; Potters, Hans

doi:10.1190/1.1820648

Cited by 20 publications

(21 citation statements)

References 2 publications

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“…This highlights the dangers in assuming that seismic frequencies represent a low frequency, even when, as in this case, the squirt flow frequency as deduced from laboratory measurement lies above the sonic frequency band. The effect we demonstrate is consistent with the observations of Guest et al (1998) concerning strong changes in shear wave splitting between brine and gas saturations.…”

Section: The Effect Of Saturationsupporting

confidence: 93%

The effect of fluid saturation in an anisotropic multi-scale equant porosity model

Chapman

Maultzsch

Liu

et al. 2003

Journal of Applied Geophysics

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Section: The Effect Of Saturationsupporting

confidence: 93%

The effect of fluid saturation in an anisotropic multi-scale equant porosity model

Chapman

Maultzsch

Liu

et al. 2003

Journal of Applied Geophysics

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“…gas at low di erential pressures that displaces oil or water). This result is qualitatively consistent with the ndings of Guest et al (1998) in which the shear splitting parameter increased due to a decrease in the S2-wave v elocity in areas believed to be saturated with highly compressible gas. This observation was made from interpretation of a single multicomponent survey in which the increase in was very well correlated with the known gas cap of the reservoir.…”

Section: Fluid Substitution Theorysupporting

confidence: 91%

“…Hence, the commonly accepted notion that P-waves are sensitive to pore uids while, except for density e ects, S-waves are not. However, multicomponent data acquired over a fractured reservoir at Natih eld, Oman, have shown a decrease in slow shear velocity and an increase in shear-splitting when gas substitutes water or oil (Guest et al, 1998). The apparent contradiction between these results and the notion that shear waves are insensitive to uids results from the violation of Gassmann's isotropic rock assumption when aligned sets of fractures make the rock anisotropic.…”

Section: Introductionmentioning

confidence: 94%

Shear wave velocity dependence on fluid saturation

Cardona¹,

Batzle²

2001

SEG Technical Program Expanded Abstracts 2001

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Sets of aligned open fractures in a background porous rock m a y result in an e ective medium that is anisotropic with respect to wave propagation. Using Brown and Korringa's uid substitution theory we show that the velocities of vertically propagating shear waves in a fractured, anisotropic rock are dependent on uid saturation. The shear-wave sensitivity to uids originates from the e ective symmetry of the fractured rock but it is in uenced by the \isotropic" porosity, the mineralogy of the rock and the bulk modulus of the saturating uid. Transversely isotropic (TI) and orthorhombic symmetry rocks will only show c hanges with saturation of near vertical propagating shear waves when the symmetry planes of the rock are tilted with respect to the vertical direction. Monoclinic and lower symmetry rocks in general will show shear wave velocity v ariations dependent on uid saturation. We c haracterize the changes in vertical shear-waves with saturation for two monoclinic symmetry models proposed by Bakulin et al. (2000) and Grechka and Tsvankin (2001). The rst model is formed by one set of vertical, micro-corrugated fractures in an isotropic background. The second is formed by one set of dipping, rotationally invariant cracks in a transversely isotropic background with vertical symmetry axis. Our results indicate that the shear wave splitting parameter increases as the compressibility of the saturating uid increases, which is consistent with recent observations that have been reported from multicomponent seismic data.

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“…Shearwave splitting is still another way to relate fractures to seismic observations, and shear-wave observations are generally believed to be independent of rock fluid content. However, this idea has been challenged recently by Guest et al (1998). They argue that the basic assumptions used in Gassmann's (1951) equation are incorrect when the reservoir is fractured.…”

Section: Introductionmentioning

confidence: 96%

Poroelastic model to relate seismic wave attenuation and dispersion to permeability anisotropy

Parra

2000

GEOPHYSICS

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A transversely isotropic model with a horizontal axis of symmetry, based on the Biot and squirt-flow mechanisms, predicts seismic waves in poroelastic media. The model estimates velocity dispersion and attenuation of waves propagating in the frequency range of crosswell and high-resolution reverse vertical seismic profiling (VSP) (250-1250 Hz) for vertical permeability values much greater than horizontal permeability parameters. The model assumes the principal axes of the stiffness constant tensor are aligned with the axes of the permeability and squirt-flow tensors. In addition, the unified Biot and squirt-flow mechanism (BISQ) model is adapted to simulate cracks in permeable media. Under these conditions, the model simulations demonstrate that the preferential direction of fluid flow in a reservoir containing fluidfilled cracks can be determined by analyzing the phase velocity and attenuation of seismic waves propagating at different azimuth and incident angles. As a result, the fast compressional wave can be related to permeability anisotropy in a reservoir. The model results demonstrate that for a fast quasi-P-wave propagating perpendicular to fluid-filled cracks, the attenuation is greater than when the wave propagates parallel to the plane of the crack. Theoretical predictions and velocity dispersion of interwell seismic waves in the Kankakee Limestone Formation at the Buckhorn test site (Illinois) demonstrate that the permeable rock matrix surrounding a low-velocity heterogeneity contains vertical cracks.

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The effect of fracture filling fluids on shear‐wave propagation

Cited by 20 publications

References 2 publications

The effect of fluid saturation in an anisotropic multi-scale equant porosity model

The effect of fluid saturation in an anisotropic multi-scale equant porosity model

Shear wave velocity dependence on fluid saturation

Poroelastic model to relate seismic wave attenuation and dispersion to permeability anisotropy

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