Geoscience Reference
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two immiscible fluid phases. In most cases, the water-
saturated case is extended to unsaturated flow assuming
that the nonwetting fluid is air at atmospheric pressure
and corresponds to a very compressible phase (Revil
et al., 2014). Recently, Smeulders et al. (2014) have used
Pride
been published in this field since the 1950s. For brevity,
we mention here only a few key papers. Enderby (1951)
and Booth and Enderby (1952) developed the first theory
for CVP in the early 1950s. The first quantitative experi-
ments were made in the 1960s by Zana and Yeager
(1967a, b, c, 1982). Oja et al. (1985) observed an inverse
electroacoustic effect called the electrosonic amplitude
(ESA). ESA involves the generation of acoustic waves
caused by the driving force of an applied electric field
or electrical current and is therefore associated with elec-
troosmotic effects (i.e., the movement of the water in
response to an electrical field due to the excess of charge
present in the pore water). It is however nothing else
than electroseismic effects in the wording commonly
used in geophysics.
The first commercially available electroacoustic instru-
ments were developed by Pen Kem, Inc. (Marlow et al.,
1990). There are now several commercially available
instruments manufactured by Colloidal Dynamics,
Dispersion Technology, and Matec. The electroacoustic
spectroscopic methods are used to determine the particle
size distribution as well as the zeta potential of the parti-
cles. Like the seismoelectric and electroseismic methods,
there are two different electroacoustic methods depend-
ing on what field is used as a driving force. CVI is the phe-
nomenon where acoustic waves are applied to a system
and a resultant electric field or current is created by the
vibration of the colloid electric double layers. Scales
and Jones (1992) were the first to recognize the effect
of polydispersity (particle size distribution) on the elec-
troacoustic measurements. A comprehensive theory
was developed by O
s model to perform laboratory experiments
between water and water-saturated core samples or
oil-saturated core samples. They found that the contrast
between water and water-saturated porous glass samples
is larger than the contrast between water and oil-
saturated porous glass samples. The contrast between
water and water-saturated Fontainebleau sandstone is
observed to be larger than the contrast between oil and
water-saturated Fontainebleau sandstone in agreement
with the models of Revil andMahardika (2013) and Revil
et al. (2014). A complete theory of the seismoelectric
conversions in porous media saturated by two immiscible
fluids will be given in this topic in Chapter 3.
In parallel to the history of the seismoelectric method
in geophysics, there is a rich history in the development
of the so-called electroacoustic spectroscopic methods to
study colloidal suspensions, concentrated dispersion,
emulsions, and microemulsions (Booth & Enderly,
1952; Marlow et al., 1983; Valdez, 1993). Debye
(1933) predicted that the passage of an acoustic wave
through an electrolyte would generate an electrical field,
the so-called ion vibration potential (IVP). Indeed, as a
sound wave passes through a solution, it is responsible
for a charge separation due to differences in the effective
masses and frictional coefficients of the solvated anions
and cations. The resulting sum of these tiny dipoles leads
to a macroscopic electrical field, which depends on
the sound wave frequency. This effect was observed a
decade later by Yaeger et al. (1949) and Derouet and
Denizot (1951).
Hermans (1938) and Rutgers et al. (1958) were the
first to report a colloid vibration potential (CVP), investi-
gating therefore the electrical field associated with the
passage of acoustic waves through a colloidal suspension.
Colloidal suspensions represent a suspension of very
small solid particles (less than fewmicrometers) in water.
They can be understood, therefore, as a special case of
very high-porosity porous media. Generally speaking,
CVP and colloid vibration current (CVI) are two phenom-
ena where acoustic waves are applied to a colloidal sys-
tem and a resultant electric field or current is created
by the vibration of the colloid electric double layers. Sev-
eral hundred of experimental and theoretical works have
'
Brien et al.
(1993) including for concentrated systems, that is, rela-
tively low-porosity materials. A review of the method
can be found in Hunter (1998) and Greenwood (2003).
'
Brien (1991) and O
'
1.7 Conclusions
We summarize the ideas developed in this chapter as fol-
lows: (1) the surface of minerals in contact with water is
charged. This charge is compensated by a charge in the
pore water, which is therefore not neutral in proximity
to the mineral grain surface. The surface charge of the
minerals is counterbalanced locally by ions that are
sorbed (and therefore
to the mineral surface),
forming the Stern layer and some ions forming a diffuse
layer that interacts with the mineral surface charge only
“
attached
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