Environmental Engineering Reference
In-Depth Information
Hydrocarbon Σ
hy
φ (1− S
w
)
φ
φ S
w
Water Σ
w
Matrix Σ
ma
(1− φ −V
sh
)
Shale Σ
sh
V
sh
Fig. 11.23
Shaly formation schematic
Question #11.5. Shaly Formation
Given: ʣ
Log
= 30.0 cu.
ʣ
ma
= 10 cu.
ʣ
hy
= 22 cu.
ʣ
w
= 100 cu.
˕N
= 37 %.
˕N
sh
= 35 %.
V
sh
= 20 %.
ʣ
sh
= 35 cu.
Find:
(a)
˕
= _______________ .
(b)
S
w
= _______________ .
(c)
S
w
= _______________ , if you had assumed this was clean instead of a shaly
formation.
Note that the equation for ʣ
Log
in shaly formations could be rearranged to read:
(
)
+
(
)
+
(
)
(
)
SSfSfSf
=
1
-
S
+
1
-
S
V
S
-
S
+
V
sh sh ma
Shalecomponent
SS
-
Log
ma
w
w
hy
w
sh
sh
ma
Clean component
Thus, an equally valid method of computing
S
w
would be to correct
ʣ
Log
for shale
using the relationship:
(
)
SS SS
cor
=
-
V
-
.
Log
sh
sh
ma
The value
ʣ
cor
can then be used in the normal equation for estimation of water satu-
ration in clean formations. Needless to say, the accuracy of
S
w
results in shaly for-
mations will be reduced due to uncertainties about the exact values of
˕
,
V
sh
, and
ʣ
sh
.
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