1887
Volume 60, Issue 3
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

We present laboratory ultrasonic measurements of shear‐wave splitting from two synthetic silica cemented sandstones. The manufacturing process, which enabled silica cementation of quartz sand grains, was found to produce realistic sandstones of average porosity 29.7 ± 0.5% and average permeability 29.4 ± 11.3 mD. One sample was made with a regular distribution of aligned, penny‐shaped voids to simulate meso‐scale fractures in reservoir rocks, while the other was left blank. Ultrasonic shear waves were measured with a propagation direction of 90° to the coincident bedding plane and fracture normal. In the water saturated blank sample, shear‐wave splitting, the percentage velocity difference between the fast and slow shear waves, of <0.5% was measured due to the bedding planes (or layering) introduced during sample preparation. In the fractured sample, shear‐wave splitting (corrected for layering anisotropy) of 2.72 ± 0.58% for water, 2.80 ± 0.58% for air and 3.21 ± 0.58% for glycerin saturation at a net pressure of 40 MPa was measured. Analysis of X‐ray CT scan images was used to determine a fracture density of 0.0298 ± 0.077 in the fractured sample. This supports theoretical predictions that shear‐wave splitting (SWS) can be used as a good estimate for fracture density in porous rocks (i.e., SWS = 100, where is fracture density) regardless of pore fluid type, for wave propagation at 90° to the fracture normal.

Loading

Article metrics loading...

/content/journals/10.1111/j.1365-2478.2011.01021.x
2011-12-20
2024-04-18
Loading full text...

Full text loading...

References

  1. Ass’adJ.M., TathamR.H. and McDonaldJ.A.1992. A physical model study of microcrack‐induced anisotropy. Geophysics57, 1562–1570.
    [Google Scholar]
  2. BaleR., GratacosB., MattocksB., RocheS., PoplavskiiK. and LiX.2009. Shear wave splitting applications for fracture analysis and improved imaging: Some onshore examples. First Break27, 73–83.
    [Google Scholar]
  3. BestA.I.1992. The prediction of the reservoir properties of sedimentary rocks from seismic measurements. Vol. Ph.D. thesis. University of Reading.
  4. BestA. and McCannC.1995. Seismic attenuation and pore‐fluid viscosity in clay‐rich reservoir sandstones. Geophysics60, 1386–1397.
    [Google Scholar]
  5. BestA.I., SothcottJ. and McCannC.2007. A laboratory study of seismic velocity and attenuation anisotropy in near‐surface sedimentary rocks. Geophysical Prospecting55, 609–625.
    [Google Scholar]
  6. ChapmanM.2003. Frequency‐dependent anisotropy due to meso‐scale fractures in the presence of equant porosity. Geophysical Prospecting51, 369–379.
    [Google Scholar]
  7. CrampinS.1981. A review of wave motion in anisotropic and cracked elastic‐media. Wave Motion3, 343–391.
    [Google Scholar]
  8. CrampinS.1984. Effective anisotropic elastic‐constants for wave propagation through cracked solids. Geophysical Journal of the Royal Astronomical Society76, 135–145.
    [Google Scholar]
  9. CrampinS.1985. Evaluation of anisotropy by shear‐wave splitting. Geophysics50, 142–152.
    [Google Scholar]
  10. HanD.‐H., NurA. and MorganD.1986. Effects of porosity and clay content on wave velocities in sandstones. Geophysics51, 2093–2107.
    [Google Scholar]
  11. HelmutH., WeldesK. and LangeR.1969. Properties of soluble silicates. Industrial and Engineering Chemistry61, 29–44.
    [Google Scholar]
  12. HudsonJ.A.1981. Wave speeds and attenuation of elastic waves in material containing cracks. Geophysical Journal of the Royal Astronomical Society64, 133–150.
    [Google Scholar]
  13. HudsonJ., PointerT. and LiuE.2001. Effective‐medium theories for fluid‐saturated materials with aligned cracks. Geophysical Prospecting49, 509–522.
    [Google Scholar]
  14. KingM.S.1966. Wave velocities in rocks as a function of changes in overburden pressure and pore fluid saturants. Geophysics31, 50–73.
    [Google Scholar]
  15. KlimentosT. and McCannC.1990. Relationships among compressional wave attenuation, porosity, clay content and permeability in sandstones. Geophysics55, 998–1014.
    [Google Scholar]
  16. van der KolkC.M., GuestW.S. and PottersJ.H.H.M.2001. The 3D shear experiment over the Natih field in Oman: The effect of fracture‐filling fluids on shear propagation. Geophysical Prospecting49, 179–197.
    [Google Scholar]
  17. MavkoG., MukerjiT. and DvorkinJ.1998. The Rock Physics Handbook . Cambdridge University Press, Cambridge , UK .
    [Google Scholar]
  18. McCannC. and SothcottJ.1992. Laboratory measurements of the seismic properties of sedimentary rocks. Geological applications of wireline logs2, 285–297.
    [Google Scholar]
  19. MurphyW., WinklerK. and KleinbergR.L.1986. Acoustic relaxation in sedimentary rocks: Dependence on grain contacts and fluid saturation. Geophysics51, 757–766.
    [Google Scholar]
  20. QianZ., ChapmanM., LiX.Y., DaiH.C., LiuE., ZhangY. and WangY.2007. Use of multicomponent seismic data for oil‐water discrimination in fractured reservoirs. The Leading Edge26, 1176–1184.
    [Google Scholar]
  21. RathoreJ.S., FjaerE., HoltR.M. and RenlieL.1995. P‐ and S‐ wave anisotropy of a synthetic sandstone with controlled crack geometry. Geophysical Prospecting43, 711–728.
    [Google Scholar]
  22. SayersC.2009. Seismic characterization of reservoirs containing multiple fracture sets. Geophysical Prospecting57, 187–192.
    [Google Scholar]
  23. SheppardW.L.1986. Corrosion and chemical resistant masonry materials handbook . Noyes Publications.
    [Google Scholar]
  24. SherlockD. and SigginsA.2004. The development of synthetic CIPS sandstones for geophysical research.
  25. ThomsenL.1995. Elastic anisotropy due to aligned cracks in porous rock. Geophysical Prospecting43, 805–829.
    [Google Scholar]
  26. ThomsenL.1986. Weak elastic anisotropy. Geophysics51, 1954–1966.
    [Google Scholar]
  27. TillotsonP., ChapmanM., BestA.I., SothcottJ., McCannC., ShangxuW. and LiX.Y.2011. Observations of fluid‐dependent shear‐wave splitting in synthetic porous rocks with aligned penny‐shaped fractures. Geophysical Prospecting59, 111–119, doi:10.1111/j.1365–2478.2010.00903.x.
    [Google Scholar]
  28. WorthingtonM.H.2008. Interpreting seismic anisotropy in fractured reservoirs. First Break26, 57–63.
    [Google Scholar]
  29. ZhuY. and TsvankinI.2006. Plane‐wave propagation in attenuative transversely isotropic media. Geophysics71, T17–T30.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1111/j.1365-2478.2011.01021.x
Loading
/content/journals/10.1111/j.1365-2478.2011.01021.x
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): Fluid saturation; Shear‐wave splitting; Synthetic fractured rock

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error