Geoscience Reference
In-Depth Information
= 0.144 meq ml
-1
)
Sample #3847A Vinegar and Waxman [1984],
T
= 25°C (
ϕ
= 0.126,
Q
v
-0.5
-2
-2.5
-1
-3
-1.5
-3.5
-4
-2
Model with salinity
Model
= 48.4 ± 1.3
σ
S
′
F
-4.5
= (18.5 ± 1.9)×10
-4
S m
-1
-2.5
-5
-1
-0.5
0
0.5
1
1.5
-1
-0.5
0
0.5
1
1.5
Log (conductivity of the pore water, S m
-1
)
Log (conductivity of the pore water, S m
-1
)
(a)
= 0.0084 meq ml
-1
)
Sample #B2
Borner
[1992],
T
= 25°C (
ϕ
= 0.194,
Q
v
0
-3
Model
-0.5
-3.5
F
= 15.7 ± 0.4
σ
S
′
= (9.8 ± 1.2)×10
-5
S m
-1
-1.0
-4
-1.5
-4.5
-2.0
-5
Model with salinity
-2.5
-5.5
-3.0
0
-6
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
Log (conductivity of the pore water, S m
-1
)
Log (conductivity of the pore water, S m
-1
)
(b)
Figure 2.8
In-phase and quadrature conductivity of rock samples and their dependence on the pore water conductivity (NaCl
solutions).
a)
Experimental data for a sample from the Vinegar and Waxman (1984) database (clayey sand). The error bars are smaller
than the size of the symbols.
b)
The same for one core sample (sandstone) from the database of Börner (1992). In both cases, the
quadrature conductivity model (materialized by the plain line) is the one described in Revil (2012). The in-phase conductivity data are
fitted using a conductivity model providing the values of the formation factor and the surface conductivity.
conductivity measurements. They found
σ
S
= 2.7 × 10
−
3
Sm
−
1
. Therefore, there is a fair agreement between the
present theory and the published experiment data. From
the surface conductivity (
σ
S
= 1.2 × 10
−
3
Sm
−
1
), the
formation factor (
F
= 18), and the value of the mobility
of the counterions in the diffuse layer [
(Na
+
,25C) =
5.2 × 10
−
8
m
2
s
−
1
V
−
1
], we can estimate the value of the
high-frequency charge density
Q
V
using the expression
β
