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Shallow-structure characterization by 2D elastic full-waveform inversion
Geophysics - Tập 76 Số 3 - Trang R81-R93 - 2011
Anouar Romdhane, Gilles Grandjean, Romain Brossier, Fayçal Réjiba, S. Operto, J. Virieux
Assessing the effectiveness of elastic full-waveform-inversion (FWI) algorithms when applied to shallow 2D structures in the presence of a complex topography is critically important. By using FWI, we overcome inherent limitations of conventional seismic methods used for near-surface prospecting (acoustic tomography and multichannel spectral analysis of surface waves). The elastic forward ...... hiện toàn bộ
Electrical properties of iron-sand columns: Implications for induced polarization investigation and performance monitoring of iron-wall barriers
Geophysics - Tập 70 Số 4 - Trang G87-G94 - 2005
Lee Slater, Jaeyoung Choi, Yuxin Wu
We investigate the electrical response (0.1–1000 Hz) of reactive iron barriers by making measurements on zero valent iron ([Formula: see text])-sand columns under the following conditions: (1) variable [Formula: see text] surface area (0.1–100% by volume [Formula: see text] under constant electrolyte chemistry; (2) variable electrolyte activity (0.01–1 mol/liter), valence (mono trivalent)...... hiện toàn bộ
Relationship between low-frequency electrical properties and hydraulic permeability of low-permeability sandstones
Geophysics - Tập 75 Số 3 - Trang E131-E141 - 2010
Norbert Zisser, Andreas Kemna, G. Nover
The relationship between low-frequency electrical properties and hydraulic permeability of rocks has been the focus of geophysical investigations for a long time because it offers a possibility for an in situ and noninvasive permeability estimation of rocks. We examined the hydraulic and low-frequency [Formula: see text] electrical properties as well as the anisotropic properties of low-p...... hiện toàn bộ
Application of a complete workflow for 2D elastic full-waveform inversion to recorded shallow-seismic Rayleigh waves
Geophysics - Tập 82 Số 2 - Trang R109-R117 - 2017
L. Groos, Martin Jörg Schäfer, Thomas Forbriger, Thomas Bohlen
The S-wave velocity of the shallow subsurface can be inferred from shallow-seismic Rayleigh waves. Traditionally, the dispersion curves of the Rayleigh waves are inverted to obtain the (local) S-wave velocity as a function of depth. Two-dimensional elastic full-waveform inversion (FWI) has the potential to also infer lateral variations. We have developed a novel workflow for the applicati...... hiện toàn bộ
Site characterization with 3D elastic full-waveform tomography
Geophysics - Tập 83 Số 5 - Trang R389-R400 - 2018
Trung Dung Nguyen, Khiem T. Tran
We have developed a 3D elastic full-waveform inversion (FWI) method for geotechnical site characterization. The method is based on a solution of 3D elastic-wave equations for forward modeling to simulate wave propagation and a local optimization approach based on the adjoint-state method to update the model parameters. The staggered-grid finite-difference technique is used to solve the wa...... hiện toàn bộ
Poroelasticity: Efficient modeling of strongly coupled, slow deformation processes in a multilayered half‐space
Geophysics - Tập 68 Số 2 - Trang 705-717 - 2003
Rongjiang Wang, Hans‐Joachim Kümpel
We present a fast, powerful numerical scheme to compute poroelastic solutions for excess pore pressure and displacements in a multilayered half‐space. The solutions are based on the mirror‐image technique and use an extension of Haskell's propagator method. They can be applied to assess in‐situ formation parameters from the surface deformation field when fluids are injected into or extract...... hiện toàn bộ
PROCESSING AND INTERPRETATION OF MAGNETOTELLURIC SOUNDINGS
Geophysics - Tập 37 Số 6 - Trang 1005-1021 - 1972
G. Kunetz
A few methods in the processing and interpretation of magnetotelluric soundings over a stratified earth are investigated, with emphasis on the less commonly used time‐domain procedures. Analytical expressions of the theoretical transfer function between the magnetic‐ and electric‐field variations, both in frequency and time domain, are derived. Their properties are studied, and recursive ...... hiện toàn bộ
Mechanical properties of shale-gas reservoir rocks — Part 2: Ductile creep, brittle strength, and their relation to the elastic modulus
Geophysics - Tập 78 Số 5 - Trang D393-D402 - 2013
Hiroki Sone, Mark D. Zoback
We studied the elastic moduli, ductile creep behavior, and brittle strength of shale-gas reservoir rocks from Barnett, Haynesville, Eagle Ford, and Fort St. John shale in a series of triaxial laboratory experiments. We found a strong correlation between the shale compositions, in particular, the volume of clay plus kerogen and intact rock strength, frictional strength, and viscoplastic cr...... hiện toàn bộ
A nonreflecting boundary condition for discrete acoustic and elastic wave equations
Geophysics - Tập 50 Số 4 - Trang 705-708 - 1985
C. Cerjan, Dan Kosloff, Ronnie Kosloff, Moshe Reshef
One of the nagging problems which arises in application of discrete solution methods for wave‐propagation calculations is the presence of reflections or wraparound from the boundaries of the numerical mesh. These undesired events eventually override the actual seismic signals which propagate in the modeled region. The solution to avoiding boundary effects used to be to enlarge the numeric...... hiện toàn bộ
The inverse problem of resistivity sounding
Geophysics - Tập 49 Số 12 - Trang 2143-2158 - 1984
Robert L. Parker
The electric potential due to a single point electrode at the surface of a layered conducting medium is calculated by means of a linear combination of the potentials associated with a set of two‐layer systems. This new representation is called the bilayer expansion for the Green’s function. It enables the forward problem of resistivity sounding to be solved very efficiently, even for comp...... hiện toàn bộ
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