Page 160 - The Geological Interpretation of Well Logs

- THE GEOLOGICAL INTERPRETATION OF WELL LOGS -

> 45 NEUTRON POROSITY UNITS % -15
9 42. 36 30 24 18 12 6 oO -6 -12
° TT TAT et oe fd TO

Qo /t.86 BULK DENSITY g/cm 2.95
- 2.0 21 2.2 23 24 25 26 27 28 2.9

5 T T T “Tt T T TT T T F T T t | T , , T

co

FLL,
limestone =O

l t

l
l

~
vats 7}
+ + +
wale SALT = HALITE |
4 ee
a4 2.98 gfcm3
.
ANHYDRITE |
(

TT PRA
ON =60e4 RARRAR GYPSUM
l ARAAAA
I ARAAAAN

{ Cc c Cc
ee

POLYHALITE, Cee —
1.57 g/cm P 7 P 1
PP

I
L
I

oh
limestone ¢?=0
boot

i I J I

Figure 10.3¢ Idealized neutron-density log, combination responses in a series of pure evaporites. (For PDC-CNL Schlumberger,
figures from Edmundson and Raymer, 1979).
both logs. The absolute values of both logs and the log matrix type can be suggested, and unusual minerals
separation (Figure 10.30) are all indicative. located with the possibility of identification.
Neutron and density values can also be used quantita-
Conclusions
tively for lithology identification. The method is
The neutron-density combination is the best lithology
described in Chapter 11 (see Cross-plotting compatible
indicator for most formations. Shales and shaliness and
logs, Section 11.6).
evaporites can be identified, clean formations and even

150