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Volume 55, Issue 3
  • E-ISSN: 1365-2478

Abstract

ABSTRACT

The impact of thermally induced microfractures on the stress‐sensitive elastic wave properties of aeolian Rotliegend sandstone samples is analysed. It is found that to identify the effects of the microfracture contribution accurately, a correction must first be made to account for water loss (representing a mass loss of 4–6%) from the pore throats and clays due to the heating process, despite care being taken to ensure that the thermally fractured samples re‐adsorb room moisture. Both the original and thermally fractured rocks are stress‐sensitive at the ultrasonic wave frequencies of the laboratory. However, a distinct shift in the estimated distribution of internal rock compliance indicates that the population of thermal microfractures differs in nature from that caused solely by core‐plug extraction damage. In particular, the ratio of normal to tangential compliance is observed to be higher for the thermally generated microfractures than for the broken grain‐grain contacts created by extraction unloading. This can be explained by the intragranular thermal‐fracture surfaces being smoother when compared to the intergranular boundaries. Mechanical hysteresis is observed between the up‐ and downgoing test cycles for both the original and, to a greater extent, the thermally fractured rock. This indicates that there is compaction‐induced movement of the fractures in the samples during application of stress in the laboratory.

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2007-04-13
2024-04-20

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References

  1. AnsteyN.A.1991. Velocity in thin section. First Break9 (10), 449–457.
    [Google Scholar]
  2. BatzleM.L., SimmonG. and SiegfriedR.W.1980. Microcrack closure in rocks under stress: direct observation. Journal of Geophysical Research85 (B12), 7072–7090.
    [Google Scholar]
  3. FarquharR.A., SmartB.G.D., ToddA.C., TompkinsD.E. and TweedieA.J.1993. Stress sensitivity of low permeability sandstones from the Rotliegendes sandstone. Proceedings of SPE Annual Technical Conference , Houston , USA , SPE 26501.
  4. FredrichJ.T. and WongT.1986. Micromechanics of thermally induced cracking in three crustal rocks. Journal of Geophysical Research91 (B12), 12743–12764.
    [Google Scholar]
  5. FreundD.1992. Ultrasonic compressional and shear velocities in dry clastic rocks as a function of porosity, clay content, and confining pressure. Geophysical Journal International108, 125–135.
    [Google Scholar]
  6. HallS.A., KendallJ.‐M. and BarkvedO.I.2002. Fractured reservoir characterization using P‐wave AVOA analysis of 3D OBC data. The Leading Edge21, 777–781.
    [Google Scholar]
  7. KingM.S.2002. Elastic wave propagation in and permeability for rocks with multiple parallel fractures. International Journal of Rock Mechanics and Mining Sciences39, 1033–1043.
    [Google Scholar]
  8. KingM.S. and MarsdenJ.R.2002. Velocity dispersion between ultrasonic and seismic frequencies in brine‐saturated reservoir sandstones. Geophysics67, 254–258.
    [Google Scholar]
  9. KranzR.L.1983. Microcracks in rocks: a review. Tectonophysics100, 449–480.
    [Google Scholar]
  10. LiuE., HudsonJ.A. and PointerT.2000. Equivalent medium representation of fractured rock. Journal of Geophysical Research105, 2981–3000.
    [Google Scholar]
  11. MacBethC.2004. A classification for the pressure‐sensitivity properties of a sandstone rock frame. Geophysics69, 497–510.
    [Google Scholar]
  12. MacBethC., StammeijerJ. and OmerodM.2005. Seismic monitoring of pressure depletion evaluated for a UKCS gas reservoir. Geophysical Prospecting54, 29–47.
    [Google Scholar]
  13. NesO.‐M., HoltR.M. and FjaerE.2000. The reliability of core data as input to seismic reservoir monitoring studies. Proceedings of SPE European Petroleum Conference , Paris , SPE 65180 .
  14. PalciauskasV.V.1992. Compressional to shear wave velocity ratio of granular rocks: Role of rough grain contacts. Geophysical Research Letters19, 1683–1686.
    [Google Scholar]
  15. Pyrak‐NolteL.J., MyerL.R. and CookN.G.1990. Transmission of seismic waves across single fractures. Journal of Geophysical Research95, 8617–8638.
    [Google Scholar]
  16. SayersC. and HanD.2002. The effect of pore fluid on the stress‐dependent elastic wave velocities in sandstones. 72nd SEG Meeting, Salt Lake City , USA , Expanded Abstracts, 1842–1845.
  17. SayersC.M. and KachanovM.1995. Microcrack‐induced elastic wave anisotropy of brittle rocks. Journal of Geophysical Research100 (B3), 4149–4156.
    [Google Scholar]
  18. SchoenbergM.1980. Elastic wave behaviour across linear slip interfaces. Journal of the Acoustical Society America68, 1516–1521.
    [Google Scholar]
  19. SchoenbergM. and NakagawaS.2001. Acoustic behaviour of fractures under static stress. 63rd EAGE Conference, Amsterdam , The Netherlands , Extended Abstracts, Session: P098.
  20. SteskyR.M.1985. Compressional and shear velocities of dry and saturated jointed rock: a laboratory study. Geophysical Journal of the Royal Astronomical Society83, 239–262.
    [Google Scholar]
  21. WulffA.‐M. and BurkhardtH.1996. The influence of local fluid flow and microstructure on elastic and anelastic rock properties. Surveys in Geophysics17, 347–360.
    [Google Scholar]
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The stress dependent elastic properties of thermally induced microfractures in aeolian Rotliegend sandstone
Geophysical Prospecting 55, 323 (2007); https://doi.org/10.1111/j.1365-2478.2007.00601.x
/content/journals/10.1111/j.1365-2478.2007.00601.x
/content/journals/10.1111/j.1365-2478.2007.00601.x
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