Geophysics
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Interpretation of depositional facies from seismic data
Geophysics - Tập 44 Số 2 - Trang 131-160 - 1979
Depositional environments can be predicted from seismic data through an orderly
approach to the interpretation of seismic reflections. One keystone to this
approach is an understanding of the effects of lithology and bed spacing on
reflection parameters. Amplitude, frequency, and continuity are some of the
parameters most useful for interpreting environments. Reflection amplitude
contains informat...
Permeability prediction based on fractal pore‐space geometry
Geophysics - Tập 64 Số 5 - Trang 1447-1460 - 1999
Estimating permeability from grain‐size distributions or from well logs is
attractive but difficult. In this paper we present a new, generally applicable,
and relatively inexpensive approach which yields permeability information on the
scale of core samples and boreholes. The approach is theoretically based on a
fractal model for the internal structure of a porous medium. It yields a general
and p...
Inversion of the geophysical inverse problem for n layers with nonuniqueness reduced to n cases
Geophysics - Tập 44 Số 4 - Trang 801-819 - 1979
A new method is described for reducing nonuniqueness in the geophysical inverse
problem for n layers to n cases, provided the ratio of characteristic impedances
of sequential layers is of the order of unity and upper and lower layer boundary
conditions are known. The method is based on impedance concepts which allow
application to a number of different electromagnetic or acoustic experimental
meth...
Building tilted transversely isotropic depth models using localized anisotropic tomography with well information
Geophysics - Tập 75 Số 4 - Trang D27-D36 - 2010
Tilted transverse isotropy (TTI) is increasingly recognized as a more
geologically plausible description of anisotropy in sedimentary formations than
vertical transverse isotropy (VTI). Although model-building approaches for VTI
media are well understood, similar approaches for TTI media are in their
infancy, even when the symmetry-axis direction is assumed known. We describe a
tomographic approac...
Viscoelastic finite‐difference modeling
Geophysics - Tập 59 Số 9 - Trang 1444-1456 - 1994
Real earth media disperse and attenuate propagating mechanical waves. This
anelastic behavior can be described well by a viscoelastic model. We have
developed a finite‐difference simulator to model wave propagation in
viscoelastic media. The finite‐difference method was chosen in favor of other
methods for several reasons. Finite‐difference codes are more portable than, for
example, pseudospectral...
2D electrical resistivity imaging of some complex landslides in Lucanian Apennine chain, southern Italy
Geophysics - Tập 70 Số 3 - Trang B11-B18 - 2005
We use high-resolution electrical resistivity imaging to delineate the geometry
of complex landslides in the Lucanian Apennine chain of southern Italy, to
identify the discontinuity between the landslide material and bedrock, and to
locate possible surfaces of reactivation. The Lucanian Apennine chain is
characterized by high hydrogeological hazard and shows a complete panorama of
mass movements. ...
A new approach to fitting induced-polarization spectra
Geophysics - Tập 73 Số 6 - Trang F235-F245 - 2008
Best fitting of induced-polarization (IP) spectra by different models of
Cole-Cole type evidences discrepancies in the resulting model parameters. The
time constant determined from the same data could vary in magnitude over several
decades. This effect, which makes an evaluation of the results of different
models nearly impossible, is demonstrated by induced polarization measurements
in the freque...
On the relationship between iron concentration and induced polarization in marsh soils
Geophysics - Tập 72 Số 1 - Trang A1-A5 - 2007
Induced polarization (IP) measurements [Formula: see text] were conducted on
seventeen clay and peat marsh soils that were subsequently analyzed for heavy
metal concentrations, moisture content, organic matter, porosity, specific
surface area, and pore fluid conductivity. A Cole-Cole model was fit to each
sample and model parameters analyzed in terms of physicochemical properties. We
found a linea...
On the estimation of specific surface per unit pore volume from induced polarization: A robust empirical relation fits multiple data sets
Geophysics - Tập 75 Số 4 - Trang WA105-WA112 - 2010
We analyze the relationship between induced polarization (IP) parameters and the
specific surface area normalized to the pore volume [Formula: see text] for an
extensive sample database. We find that a single linear imaginary
conductivity-[Formula: see text] relation holds across a range of
single-frequency IP data sets composed of sandstones and unconsolidated
sediments that lack an appreciable m...
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
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),
and pH ...
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