Page 138 - The Geological Interpretation of Well Logs

- THE GEOLOGICAL INTERPRETATION OF WELL LOGS -
PEF LOG
* SCALE: barns/electron
0 2 4 6 8 10

SHALE

QUARTZITE
SANDSTONE $ 10%
0
LIMESTONE
$ 10%
$0
DOLOMITE
4 10%

SHALE {typical)
GAS xt
SANDSTONE ol e
> 20% ---
WATER S
poorly
compacted
\ varlable, depends
on composition
SHALE
not texture
4 3.0- 5.0
compact

COAL
SALT cave

SHALE + SIDERITE -8
wees
with barite,
SHALE 1 ' wocoe extremaly high
Figure 9.25 The PEF or Photoelectric Factor log. The log is a measure of the combined atomic complexity of the formation so that
porosity effects are minimal. The lithologies are comparable to those used in Figures 9.1 and 10.1,
* a Barn is 10cm?,

Pe
2.
is.
0 1 (1.54) 2 (2.66) 3 t 4 (4.23) 5 6 35%

‘ ! \
a I I 30%
¢ ’
b I
|
; i t 4 ‘ 1 | ' ! ' 1 r [20% = >
1 ' ‘ q 1 { \ ' r 10% a
9
3
'
(
\
+
1
\
t

‘
\
‘
N
(1.81)
{5.08)
3 (3.14)
0% {MATRIX}
QUARTZ DOLOMITE CALCITE
-——— water filled porosity (fresh)
——- gas filled poresity (methane)
Figure 9.26 PEF values of quartz, dolomite and calcite over the porosity
range from 0 to 35%. Porosity generally has only a subsidiary effect on the
PEF value: matrix type is more important. (Modified from Gardner and
Dumanoir, 1980).
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