Seismic characterization of poroelastic structures using the theory of stochastic wave propagation and finite-difference simulations

• Applicant: Dr. Tobias Müller
• Subject Area: Geophysics
• Term: from 2002 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5372846

• Final Report Year: 2011

Final Report Abstract

Central result is the theoretical analysis of the conversion scattering mechanism from propagating wave modes into diffusion waves in randomly inhomogeneous poroelastic solids and the formulation of a dynamic-equivalent medium theory in 3D space in analogy to the generalized O'Doherty-Anstey theory for scattering in elastic solids. It has become apparent that the diffusion wave conversion scattering mechanism (fast P --> slow P-wave) is a major source of seismic wave dissipation in the frequency band relevant for seismic exploration. On the basis of these results several rock physics models have been developed including models for the acoustic signatures of a) partially saturated rocks, b) strong permeability fluctuations. These models enabled the quantitative interpretation of laboratory experiments on core samples carried out by our collaborators at Curtin University of Technology. Another major achievement is the simulation of this wave conversion scattering mechanism using a modified finite-difference scheme in 2D and conventional finite-element scheme in 3D. For the first time we were able to demonstrate and quantify the attenuation anisotropy due to the wave-induced flow mechanism. These numerical results triggered the development of further theoretical analysis leading to the so-called generalized poroelastic Backus theory. Though not originally planned, the quasi-static finite-element simulations provided a useful means to analyze the spatio-temporal evolution of fluid-induced micro-earthquakes in stressed rock masses. In collaboration with the tectonic stress group a new understanding of the coupling between fluid pressure and regional stress field has been elaborated. Indicators of the success and impact of the research carried out by the junior research group include a) more than 25 peer-reviewed publications in international journals of geophysical and applied physics scope, b) award from the Australian Society of Exploration Geophysicists, c) participation in a couple of still on-going, industry-funded projects, d) creation of a seismic rock physics research team at the division of Earth Science & Resource. Engineering of CSIRO (established in September 2008 and lead by T. Müller since then) that continues the research along the lines of the junior research group. In conclusion, the continuing funding of Phase I and II within the Emmy-Noether program enabled the development of a sound theoretical basis of fluid-rock interactions constituting a fundamental contribution to the vastly growing field of rock physics. The research outcome continues to trigger industry-funded projects in the realm of oil and gas reservoir characterization, geo-sequestration of carbon dioxide, and unconventional resources exploration.

Publications

• Wave-induced fluid flow in random porous media: Attenuation and dispersion of elastic waves. Journal of the Acoustical Society of America, Vol. 117. 2005, Issue 5, pp. 2732-2741.
  Müller, T. M., Gurevich, B.
  
• Comparative review of theoretical models for elastic wave attenuation and dispersion in partially saturated rocks. Soil Dynamics and Earthquake Engineering, Vol. 26. 2006, Issues 6–7, pp. 548–565.
  Toms, J., Müller, T. M., Ciz, R., Gurevich, B.
  
• Seismic attenuation due to wave-induced flow: Why Q in random structures scales differently. Geophysical Research Letters, Vol. 33. 2006, Issue 16, L16305.
  Muller, T.M., Rothert, E.
  
• Dynamic permeability of porous rocks and its seismic signatures. Geophysics, Vol. 72. 2007, no. 5, p. E149-E158.
  Muller, T. M., Lambert, G.P., Gurevich, B.
  
• Fluid substitution, dispersion, and attenuation in fractured and porous reservoirs—insights from new rock physics models. The Leading Edge, Vol. 26 no. 9, pp. 1162-1168.
  Gurevich, B., Galvin, R. J., Brajanovski, M.,, Muller, T. M., Lambert, G.
  
• Seismic attenuation in porous rocks with random patchy Saturation. Geophysical Prospecting, Vol. 55. 2007, Issue 5, pp. 671–678.
  Toms, J., Müller, T. M., Gurevich, B.
  
• Attenuation of seismic waves due to waveinduced flow and scattering in random porous media. In: Earth heterogeneity and scattering effects on seismic waves, Eds. H. Sato, M. Fehler, Advances in Geophysics, Vol. 50. 2008, pp. 123-166, Elsevier.
  Muller, T. M., Gurevich, B., Shapiro, S.A.
  
• Modeling elastic and poroelastic wave propagation in complex geological Structures. In: High Performance Computing in Science and Engineering '07, Eds., W. E. Nagel, D. Kroner, M. Resch. Springer, 2008, pp 587-601.
  F. Wenzlau, T. Xia, T. M. Muller
  
• Simulating 3-D seismograms in 2.5D heterogeneous structures by combining 2D nite-difference modelling and ray tracing. Geophysical Journal International, Vol. 174. 2008, Issue 1, pp. 309-315.
  Miksat, J., Müller, T. M., Wenzel, F.
  
• Direct laboratory observation of patchy Saturation and its effects on ultrasonic velocities. The Leading Edge, vol. 28. 2009, Issue 1, pp. 24-27.
  Lebedev, M., Toms-Stewart, J., Clennell, B., Pervukhina, M., Shulakova, V., Paterson, L., Müller, T.M., et al.
  
• Green's functions and radiation patterns in poroelasticity revisited. Geophysical Journal International, Vol. 178.2009, Issue 1, pp. 327-337.
  Karpfinger, F., Müller, T. M., Gurevich, B.
  
• Microseismic signatures of non-linear pore-fluid pressure diffusion. Geophysical Journal International, Vol. 179. 2009, Issue 3, pp. 1558-1565.
  Hummel, N., Müller, T. M.,
  
• P-wave dispersion and attenuation in fractured and porous reservoirs { poroelasticity Approach. Geophysical Prospecting, Vol. 57. 2009, Issue 2, pp. 225–237.
  Gurevich, B., Brajanovski, M., Galvin, R. J., Müller, T. M., Toms-Stewart, J.
  
• Ansiotropic dispersion and attenuation due to wave-induced flow: quasi-static nite-element modeling in poroelastic solids. Journal Geophysical Research (JGR):Solid Earth, Vol. 115. 2010, Issue B7, B07204.
  Wenzlau, F., Altmann, J. B., Müller, T. M.
  
• Poroelastic contribution to the reservoir stress path. International Journal of Rock Mechanics and Mining Sciences, Vol. 47. 2010, Issue 7, pp. 1104–1113.
  Altmann, J. B., Müller, T. M., Muller B. I. R., Tingay, M. R. P., Heidbach, O.
  
• Seismic wave attenuation and Dispersion resulting from wave-induced flow in porous rocks - a review. Geophysics Volume 75, Issue 5, pp. 75A147-75A164.
  Müller, T. M., Gurevich, B., Lebedev, M.
  
• Anisotropic P-SV-wave dispersion and attenuation due to inter-layer flow in thinly layered porous rocks. Geophysics, vol. 76.2011, pp. WA135-WA145.
  Krzikalla F., Müller, T.M.
  
• Fast compressional wave attenuation and dispersion due to conversion scattering into slow shear waves in randomly heterogeneous porous media. Journal of the Acoustical Society of America, Vol. 129. 2011, Issue 5, pp. 2785-2796.
  Müller, T. M., Sahay, P. N.
  
• Porous medium acoustics of wave-induced vorticity diffusion. Applied Physics Letters, Vol. 98. 2011, Issue 8, 084101.
  Müller, T. M., Sahay, P. N.