Page 14 - The Geological Interpretation of Well Logs

- THE GEOLOGICAL INTERPRETATION OF WELL LOGS -

5-10% of total well costs is expensive, so that in cheap, each well represents hard-gained information. Cutting
onshore wells, in known terrain, a minimum set is run, down on well logs is probably a false economy, but it can
Offshore, where everything is expensive, full sets of logs be forgiven when prices are considered.
are generally run, even if hydrocarbons are not found, as
ORILLING CURVE
LOGGING RECORD om

{0 109s)

400m-750m |
ISF-sonle run 1
LOGS RUN 750m

+ 1000m
casings CEPTH
750m-1650m
ISF-sonic, run 2 CN, DRILLING
FOC-CNL, run 1
HOT, run 1
1650m-2 100m
ISF-sonic, run a
FDC~-CNL, run 2 reservoir
OLL. run 1 r-2000m
HOT, run 2 FINAL LOGS AUN }~

10
9
30
20
40
60
DRILLING DAYS
Figure 1.5 Logging record. Log runs are indicated on a typical offshore drilling curve. Horizontal lines indicate no drilling,
when logs are run. Casing follows logging. Note log run numbers. (Too] mnemonics - Schlumberger, see Appendix).
{———— TRACK ——) é————TRACK 2 =) 4 TRACK 3
0 5 10 0 S 10 15 20
NY
a
So
°
LINEAR

0.2 1 10 100 1000 2000
tw
a
LOGARITHMIC 2
2

0.2 7 10 20.0
nm
@
a
o
HYBRIO

Figure 1.6 Three typical API jog formats. Tracks are 2.5in wide with a central 0.7Sin depth column, Overall width is 8.25in,
Vertical scales are variable (see text).