Experimental verification of the anisotropic Gassmann model for fluid substitution in fractured reservoirs

Luke Brown; Boris Gurevich

doi:10.1071/ASEG2003ab018

ISSN: 2202-0586
E-ISSN:

oa Experimental verification of the anisotropic Gassmann model for fluid substitution in fractured reservoirs
Authors Luke Brown^a and Boris Gurevich^b
View Affiliations Hide Affiliations

^a Curtin University, , Australia, [email protected] ^b Curtin University, , Australia, [email protected]
Publisher: Australian Society of Exploration Geophysicists
Source: ASEG Extended Abstracts, Volume 2003, Issue ASEG2003 - 16th Geophysical Conference, Aug 2003, p. 1 - 5
DOI: https://doi.org/10.1071/ASEG2003ab018
- Published online: 01 Aug 2003

Abstract

Porous reservoirs with aligned fractures exhibit frequency dependent seismic anisotropy due to wave induced fluid flow between pores and fractures. We model this frequency dependent anisotropy by combining the low-frequency anisotropic Gassmann model with the Hudson et al. model for frequency dependent properties of a porous material with penny-shaped cracks.

The predictions of the anisotropic Gassmann model are compared with experimental measurements of elastic wave velocities as function of angle for a synthetic sample with aligned disc-like cracks. The properties of the host rock and fracture compliances are obtained from P, SV, and SH velocities measured on the dry sample. The dry fractured porous rock properties serve as input to anisotropic Gassmann fluid substitution model, which is used to compute the saturated rock properties. The stiffnesses of the saturated fractured porous rock are used to calculate the angular dependent compressional and shear wave velocities. The predicted velocities are then compared to the measured velocities. The agreement is reasonably good for both S-wave velocities, but P-wave anisotropy is overestimated by about 25%.

This discrepancy can be explained by the fact that the low frequency assumption of the anisotropic Gassmann model does not account for the fluid diffusion effects occurring at relatively high frequencies used in the experiment (100 KHz). A combination of the low frequency anisotropic Gassmann model with the Hudson et al. frequency dependency accounts for fluid diffusion effects and results in an excellent agreement for P- as well as S- waves.

Article metrics loading...

/content/journals/10.1071/ASEG2003ab018

2003-08-01

2026-01-13

From This Site

/content/journals/10.1071/ASEG2003ab018

dcterms_title,dcterms_subject,pub_keyword

-contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution

10

5

Full text loading...

References

Brown, R.J.S., and Korringa, J., 1975, On the dependence of the elastic properties of a porous rock on the compressibility of the pore fluid: Geophysics, 40, 608-616.
Cardona, R., 2002, Two theories for fluid substitution in porous rocks with aligned cracks: 72d Ann. Mtg., Soc. Eexpl. Geophys., Expanded Abstracts, Paper ANI 3.5.
Gassmann, F., 1951, Uber die Elastizitat poroser Medien: Viertel. Naturforsch. Ges. Zurich, 96, 1-23.
Gurevich, B., 2002, Elastic properties of saturated porous rocks with aligned fractures: 72d Ann. Mtg., Soc. Eexpl. Geophys., Expanded Abstracts, Paper ANI PI.6.
Hudson, J.A., Liu, E., and Crampin, S., 1996, The mechanical properties of materials with interconnected cracks and pores: Geophys. J. Internat, 124, 105-112.
Hudson, J.A., Pointer, T., and Liu, E., 2001, Effective medium theories for fluid saturated material with aligned cracks: Geophys. Prosp., 49, 509-522.
Rathore, J.S., Fjaer, E., Holt, R.M., and Renlie, L., 1995, P-and S-wave anisotropy of a synthetic sandstone with controlled crack geometry: Geophys. Prosp., 43, 711-728.
Schoenberg, M., and Douma, J., 1988, Elastic-wave propagation in media with parallel fractures and aligned cracks: Geophys. Prosp., 36, 571-590.
Schoenberg, M., and Sayers, CM., 1995, Seismic anisotropy of fractured rock: Geophysics, 60, 204-211.
Thomsen, L., 1986, Weak elastic anisotropy: Geophysics, 51, 1954-1966.
Thomsen, L., 1995, Elastic anisotropy due to aligned cracks in porous rock: Geophys. Prosp., 43, 805-829.
Xu, S., 1998, Modelling the effect of fluid communication on velocities in anisotropic porous rocks: Int. J. Solids Structures, 35, 4685-4704.

/content/journals/10.1071/ASEG2003ab018

Article Type: Research Article

Keyword(s): anisotropy; dispersion; effective medium; fractures; poroelasticity

Most Cited This Month Most Cited RSS feed

- Inversion of data from electrical imaging surveys in water-covered areas
  
  Authors M. H. Loke and J. W. Lane
- Inversion of Magnetic Data from Remanent and Induced Sources
  
  Authors Robert G. Elllis, Barrry de Wet and Ian N. Macleod
- A comparison of smooth and blocky inversion methods in 2-D electrical imaging surveys
  
  Authors M. H. Loke, Ian Acworth and Torleif Dahlin
- Designing matched bandpass and azimuthal filters for the separation of potential-field anomalies by source region and source type
  
  Authors Jeffrey D. Phillips
- Bad Colour Maps Hide Big Features and Create False Anomalies
  
  Authors Peter Kovesi
- Practical 3D EM inversion – the P223F software suite
  
  Authors Art Raiche, Fred Sugeng and Glenn Wilson
- Estimating Noise Levels in AEM Data
  
  Authors Andy Green and Richard Lane
- Target delineation using Full Tensor Gravity Gradiometry data
  
  Authors Colm A. Murphy and James Brewster
- Transdimensional Monte Carlo Inversion of AEM Data
  
  Authors Ross C Brodie and Malcolm Sambridge
- The geotech VTEM time domain helicopter em system
  
  Authors Ken Witherly, Richard Irvine and Edward Morrison
More Less

oa Experimental verification of the anisotropic Gassmann model for fluid substitution in fractured reservoirs

Abstract

Most Read This Month

Most Cited This Month Most Cited RSS feed