1887

Abstract

Summary

We present a study of shear-wave splitting using microseismic sources in a highly anisotropic shale gas reservoir. We observe very strong anisotropy (up to 30% in some cases) with a predominantly VTI symmetry (vertical transverse isotropy). Splitting is strongest for near-horizontal rays where the SH leads SV, however, for steeper inclinations SV is faster and we observe a triplication in the SV wavefront. Although much of this anisotropy can be explained due to the intrinsic anisotropy of the phyllosilicate material, we suggest that an additional contribution from horizontal microcracks with low hydraulic connectivity may be required to produce the observed patterns of anisotropy. This has important implications for fracture treatments, as the reactivation and interaction of these horizontal cracks with induced hydraulic fractures may be an important mechanism to facilitate gas flow.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201600999
2016-05-30
2024-04-19
Loading full text...

Full text loading...

References

  1. Baird, A. F., J.-M. Kendall, J. P. Verdon, A. Wuestefeld, T. E. Noble, Y. Li, M.
    Dutko, and Q. J. Fisher, 2013, Monitoring increases in fracture connectivity during hydraulic stimulations from temporal variations in shear wave splitting polarization. Geophysical Journal International, 195, 1120–1131
    [Google Scholar]
  2. Caddick, J., J.-M.Kendall and D. G.Raymer
    , 1998, Maslov shear-waveforms in highly anisotropic shales and implications for shear-wave splitting analyses. Oil & Gas Science and Technology - Rev. IFP Energies nouvelles, 53, 629–642.
    [Google Scholar]
  3. Dellinger, J. A.
    , 1991, Anisotropic seismic wave propagation. PhD Thesis, Stanford University.
    [Google Scholar]
  4. Kendall, J.-M., Q. J. Fisher, S. Covey Crump, J. Maddock, A. Carter, S. A. Hall, J. Wookey, S. L. A. Valcke, M. Casey, G.
    Lloyd and W. Ben Ismail. 2007. Seismic anisotropy as an indicator of reservoir quality in siliciclastic rocks. Geological Society, London, SpecialPublications, 292 123–136.
    https://doi.org/Special Publications [Google Scholar]
  5. Sayers, C.
    2005. Seismic anisotropy of shales. Geophysical Prospecting, 53, 667–676.
    [Google Scholar]
  6. Valcke, S. L. A., M. Casey, G. E. Lloyd, J.-M. Kendall and Q. J.Fisher
    . 2006. Lattice preferred orientation and seismic anisotropy in sedimentary rocks. Geophysical Journal International, 166, 652–666.
    [Google Scholar]
  7. Verdon, J.P., and A.Wüstefeld
    , 2013, Measurement of the ratio of normal/tangential compliance ratio (ZN/ZT) during hydraulic fractures stimulation using shear wave splitting data. Geophysical Prospecting, 62, 461–475.
    [Google Scholar]
  8. Wuestefeld, A., O. Al-Harrasi, J. P. Verdon, J.
    Wookey, and J.-M. Kendall, 2010, A strategy for automated analysis of passive microseismic data to image seismic anisotropy and fracture characteristics. Geophysical Prospecting, 58, 755–773.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201600999
Loading
/content/papers/10.3997/2214-4609.201600999
Loading

Data & Media loading...

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