Shales typically have low permeabilities due to their fine grain size, unless fractures are present to provide fluid conduits. Both aligned fractures and the preferred orientation of phyllosilicate minerals in shales are effective mechanisms to produce seismic anisotropy. Microseismicity recorded during hydraulic fracture stimulation can be used to provide excellent estimates of anisotropy through the observation of shear wave splitting. Here I illustrate through examples how these measurements can be used to infer the development and evolution of vertical fracture parameters during stimulation as well as provide improved estimates of the in situ rock fabric. A key challenge is untangling intrinsic anisotropy due to mineral alignment from extrinsic anisotropy due to cracks and pores aligned parallel to the dominate petrofabric of the shales. This may be improved by incorporating petrofabric and microstructural analyses of shale samples from the reservoir to better constrain the orientations and proportions of the constituent minerals.


Article metrics loading...

Loading full text...

Full text loading...


  1. Allan, A. M., Clark, A. C., Vanorio, T., Kanitpanyacharoen, W., and Wenk, H.-R.
    [2016] On the evolution of the elastic properties of organic-rich shale upon pyrolysis-induced thermal maturation. Geophysics81 (3), D263–D281.
    [Google Scholar]
  2. Baird, A. F., Kendall, J.-M., Fisher, Q. J., Budge, J.
    [2017] The role of texture, cracks and fractures in highly anisotropic shales. Journal of Geophysical Research: Solid Earth, 122 (12).
    [Google Scholar]
  3. Baird, A. F., Kendall, J-M., Verdon, J. P., Wuestefeld, A., Noble, T. E., LiY., Dutko, M., Fisher, Q. J.
    [2013] Monitoring increases in fracture connectivity during hydraulic stimulations from temporal variations in shear-wave splitting polarization. Geophysical Journal International, 195 (2), 1120–1131.
    [Google Scholar]
  4. Carcione, J. M., and Avseth, P.
    [2015] Rock-physics templates for clay-rich source rocks. Geophysics80 (5), D481–D500.
    [Google Scholar]
  5. Sayers, C.
    , [2005] Seismic anisotropy of shales. Geophysical Prospecting, 53, 667–676.
    [Google Scholar]
  6. Thomen, L.
    [1986] Weak elastic anisotropy. Geophysics51 (10), 1954–1966.
    [Google Scholar]
  7. Verdon, J. P., Kendall, J.-M. and Wuestefeld, A.
    [2009] Imaging fractures and sedimentary fabrics using shear wave splitting measurements made on passive seismic data, Geophysical Journal International, 179, 1245–1254.
    [Google Scholar]
  8. Wuestefeld, A., Al-Harrasi, O., Verdon, J. P., Wookey, J. and Kendall, J-M.
    [2010] Strategies for a fully automated passive microseismic anisotropy analysis, Geophyical. Prospecting, 58, 755–773.
    [Google Scholar]

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