Environmental Engineering Reference
In-Depth Information
Table 11.2
Capture cross
sections of compounds
Compound
Element
ʣ (cu)
Basic minerals
Quartz
SiO
2
4.2
Calcite
CaCo
3
7.3
Dolomite
CaCo
3
MgCo
3
4.8
Feldspars
Albite
NaAlSi
3
o
8
7.6
Anorthite
CaAlSi
2
O
8
7.4
Orthoclase
KAlSi
3
o
8
15
Evaporites
Anhydrite
CaSO
4
13
Gypsum
CaSO
4
· H
2
O
19
Halite
NaCl
770
Sylvite
KCl
580
Carnallite
KCl · MgCl
2
· 6H
2
O
370
Borax
Na
2
B
4
O
7
· 10H
2
O
9,000
Kernite
Na
2
B
4
O
7
· 4H
2
O
10,500
Iron-bearing mineral
s
Goethite
FeO(OH)
89
Hematite
Fe
2
O
3
104
Magnetite
Fe
3
O
4
107
Limonite
FeO(OH) · 3H
2
O
80
Pyrite
FeS
2
90
Siderite
FeCO
3
52
Miscellaneous clays and micas
Glauconite
22 + 5
Chlorite
25 + 5
Mica/biotite
35 + 10
Pyrolusite
MnO
2
440
Manganite
MnO(OH)
400
Cinnabar
HgS
7,800
Shales
35-55
Basic Interpretation
Clean Formations
Practical interpretation of pulsed neutron logs is conceptually very simple. The total
formation capture cross section, ʣ, recorded on the log, is just the sum of the prod-
ucts of the volume fractions found in the formation and their respective capture
cross sections. Thus, in its simplest form,
(
)
+
SS fSf
Log
=
× -
1
×
matrix
fluid
Figure
11.20
should clarify the mathematical relationship.
Search WWH ::
Custom Search