Quasi-static finite element modeling of seismic attenuation and dispersion due to wave-induced fluid flow in poroelastic media
- Autor(en)
- Beatriz Quintal, Holger Steeb, Marcel Frehner, Stefan M. Schmalholz
- Abstrakt
The finite element method is used to solve Biot’s equations of consolidation in the displacement pressure (u-p) formulation. We perform one-dimensional (1D) and two-dimensional (2D) numerical quasi-static creep tests of a partially saturated poroelastic rock to calculate the complex and frequency dependent P-wave modulus from the modeled stress-strain relations. The P-wave modulus is used to calculate the corresponding frequency-dependent attenuation (i.e., inverse of quality factor) and phase velocity of the rock. The frequency-dependent attenuation and velocity dispersion are due to fluid flow induced by pressure differences between areas of the poroelastic rock saturated with different fluids. A comparison of our numerical results with analytical solutions and theoretical high- and low-frequency limits for the quality factor and phase velocity demonstrates its accuracy and stability for a wide range of frequencies (six orders of magnitude). The algorithm employs an unstructured mesh and a variable time stepping which make it efficient and accurate for 2D simulations with arbitrary, e.g. curved, geometries. We further numerically calculate the quality factor and phase velocity for 1D layered partially saturated porous rock exhibiting random distributions of both the layer thickness and the partial saturation. We show that the numerical results for the random distributions can be approximated using a volume average of White's analytical solution for interlayer-flow. Implications and applications of our results to frequency-dependent reflection coefficients of reservoirs at low frequencies are discussed.
- Organisation(en)
- Institut für Geologie
- Externe Organisation(en)
- Eidgenössische Technische Hochschule Zürich, Ruhr-Universität Bochum (RUB)
- Journal
- Journal of Geophysical Research - Solid Earth
- Band
- 116
- ISSN
- 2169-9313
- DOI
- https://doi.org/10.1029/2010JB007475
- Publikationsdatum
- 01-2011
- Peer-reviewed
- Ja
- ÖFOS 2012
- 101014 Numerische Mathematik, 105102 Allgemeine Geophysik
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/1d6b5245-ae05-49f1-a19e-be1e279feaf6