Generalized Effective Biot Theory and Seismic Wave Propagation in Anisotropic, Poroviscoelastic Media. Issue 3 (3rd March 2022)

• Record Type: Journal Article
• Authors: Huang, Xingguo; Greenhalgh, Stewart; Han, Li; Liu, Xu
• Is Part Of: Journal of geophysical research. Volume 127:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-03
• Subjects: Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2021JB023590
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The interior of the Earth is quite complex due to the actual geometrical structure and the presence of complex rheological materials, including viscoelastic rocks, porous sediments and the presence of anisotropy. Seismic wavefield forward modeling in such media forms the basis of most wave equation‐based methods for investigating the structure of the Earth and processing and imaging of seismic data, e.g., seismic full waveform inversion. Numerical modeling using Biot's equations that describe the physics of poroelasticity provides a useful framework to investigate wave attenuation and dispersion. Poroelasticity describes the interaction between the deformation of an elastic porous solid and the fluid flow in the porous structure. We present a time‐domain finite‐difference method for seismic wavefield modeling, taking into account both attenuation and anisotropy of poroviscoelastic Earth structure. The mathematical formulations and modeling methods are based on (a) the linear Biot's poroelastic theory and double porosity models in anisotropic media and (b) a relaxation function that uses the generalized standard linear solid model with anisotropic τ parameter for magnitude of attenuation and nearly constant Q model. Using a modified relaxation function that is suggested to describe the anisotropy attenuation, we develop a generalized anisotropic Biot model in the anisotropic, viscoelastic media. In addition to the anisotropic poroelasticity based on Biot theory, we implement the generalized anisotropic Biot model with complex moduli for an effective Biot's model in which the attenuative anisotropic viscoelastic model with the generalized standard linear solid model is used to approximate the attenuation factor function. The method generalizes the linear poroviscoelastic model based on effective Biot theory for seismic wave modeling to the attenuative, anisotropic case. In the anisotropic, poroviscoelastic model, we represent the bulk modulus and shear modulus of the solid frame by the modified relaxation function. We present time‐domain finite‐difference modeling for seismic wavefields in anisotropic, viscoelastic porous media including transversely isotropic media with a vertical, tilted or horizontal symmetry axis (VTI, TTI, and HTI). We also consider the extension of the two new models to nearly constant Q viscoelastic anisotropy. Plain Language Summary: Wave propagation in porous geological structures and dissipative media is practical importance in the Earth Sciences. The applications include various fields such as environmental, geothermal, oil, and gas, geotechnical, earthquake engineering. Thus, understanding the mechanism that drives poroviscoelastic Earth structure will help to find a solution to geothermal, oil, and gas, and understand the Earth's interior better. This study takes into account both attenuation and anisotropy of poroviscoelastic Earth structure to create a model for seismic wavefield modeling. The mathematical formulations and modeling methods for generalized effective Biot theory based on the attenuative anisotropic, viscoelastic model are presented. Our results demonstrate a high complex seismic wave propagation as well as the interior of the Earth is quite complex due to the actual geometrical structure. Furthermore, the study shows the seismic propagation with complex geophysical models in the interior of the Earth. Key Points: The derivation of generalized effective Biot theory based on the attenuative anisotropic, viscoelastic model are presented Using a modified relaxation function, a generalized anisotropic Biot model in the anisotropic, viscoelastic media is developed A seismic wavefield modeling method, taking into account both attenuation and anisotropy of poroviscoelastic Earth structure is presented