
Publication History:
This article was
prepared especially for "Crain's Petrophysical Handbook" by
E. R. (Ross) Crain, P.Eng. in 2018.
This webpage version is the copyrighted intellectual
property of the author.
Do not copy or distribute in any form without explicit
permission. 
DEPTH PLOT BASICS
Log data depth plots are described by the depth
scale, number of presentation tracks, and the curve names and scales for each
that appear in each track. Logs recorded in the field usually have 3 tracks, one
on the left of the depth values and two on the right, the latter may be combined
into a single wide track. Depth plots that contain computed results, with or
without raw data, can have any number of tracks.
The tables below give details of the common depth scales and curve complement
for a few of the more common log suites. The curve name table shows the
socalled "correlation track" first; it would appear as the left hand track of
almost every depth plot.
A composite plot can merge several log displays into a single plot with any
number of tracks, and may also have tracks with computed petrophysical results.
Customized depth plots are common, but to make life easier for those who have to
use the data, it pays to make the plots as uniform as possible. This means the
curve scale direction, scale values, line colours, line codes, and overall
layout are consistent over time and location.
An excellent lowcost LAS File View and Depth Plot program
is available at
Everett Energy
Software. Follow the link to view a
detailed features list.
PRACTICAL CONSIDERATIONS
Traditional depth plots of well log data are 8.25
inches wide so they can be printed on standard 8.5 inch paper at full size. If
you create a wider plot, printer defaults will shrink both width and length so
it will no longer be at the depth scale you specified. You can still see it full
size on the computer screen but not on a simple printer. Professional software
and wide bed printers overcome this limitation.
For the well log descriptions listed in the tables below, the standard API well log
layout is recommended. It consists of 3 tracks, each 2.5 inches wide, with a
0.75 inch wide depth track between Tracks 1 and 2. See examples in the next
Section. Each track is divided vertically into 10 equal divisions for linear
scales, or into 3 or 4 logarithmic cycles for logarithmic scales.
A log header with log name and well location (and
other useful information) is placed at the top of the log, followed by the curve
names and scale information, centered over the appropriate track. Most log
headers generated by commercial software omits critical information. The header
should include the analyst's name, contact information, and time/date stamp.
There is nothing more frustrating than trying to sort these items out two years
after the plot was made.
For composite plots of raw data or computed results, a 4 track presentation that
fit standard printers is a de facto standard. It consists of a 0.5 inch depth
track on the left, followed by 4 tracks of width 1.875 inches. More width and
more tracks are often seen, but usually at reduced scale when printed, except
for those with expensive wide bed printer/plotters.
An excellent lowcost LAS
File View and Depth Plot program is available at
Everett Energy
Software. Follow the link to view a
detailed features list.
LAS file editing and repair software is available from
KC Petrophysics
(free and commercial versions). Follow the link to view a detailed
features list.
DEFAULT PLOT LAYOUTS
STANDARD DEPTH SCALES and GRID LINES 
Scale 
Depth # Every 
Grid Lines 
Ratio 
Units 
Description 

4 pt 
2 pt 
1 pt 
1:1200 
English 
1 inch = 100 feet 
100 feet 
200 feet 
100 feet 
20 feet 
1:1200 
Metric 
1 inch = 100 feet 
50 meters 
100 meters 
50 meters 
10 meters 
1:600 
English 
2 inches = 100 feet 
100 feet 
100 feet 
50 feet 
10 feet 
1:600 
Metric 
2 inches = 100 feet 
50 meters 
100 meters 
50 meters 
10 meters 
1:480 
English 
2.5 inches = 100 feet 
100 feet 
100 feet 
50 feet 
10 feet 
1:480 
Metric 
2.5 inches = 100 feet 
50 meters 
100 meters 
50 meters 
10 meters 
1:240 
English 
5 inches = 100 feet 
50 feet 
50 feet 
10 feet 
2 feet 
1:240 
Metric 
5 inches = 100 feet 
25 meters 
25 meters 
10 meters 
1 meter 
1:1000 
English 
1 cm = 100 meters 
100 feet 
200 feet 
100 feet 
20 feet 
1:1000 
Metric 
1 cm = 100 meters 
50 meters 
100 meters 
50 meters 
10 meters 
1:500 
English 
1 cm = 100 meters 
100 feet 
200 feet 
100 feet 
20 feet 
1:500 
Metric 
1 cm = 100 meters 
50 meters 
50 meters 
25 meters 
5 meters 
1:200 
English 
1 cm = 100 meters 
50 feet 
50 feet 
10 feet 
2 feet 
1:200 
Metric 
1 cm = 100 meters 
25 meters 
25 meters 
10 meters 
1 meter 
RECOMEMDED DEPTH PLOT LAYOUTS 
Curve 
Name 
Left 
Right 
M
or E 
Log / Linear 
Colour 
Width 
Line Code 
Correlation Track  All Logs  Track 1 






GR 
Gamma Ray 
0 
150 
api 
Linear 
Red 
2 
Solid 
SP 
Spontaneous Potential 
80 
+20 
mv 
Linear 
Blue 
2 
Solid 
Metric 








CAL 
Caliper 
150 
375 
mm 
Linear 
Black 
2 
Long Dash 
BITZ 
Bit Size 
150 
375 
mm 
Linear 
Black 
1 
Short Dash 
English 








CAL 
Caliper 
6 
16 
in 
Linear 
Black 
2 
Long Dash 
BITZ 
Bit Size 
6 
16 
in 
Linear 
Black 
1 
Short Dash 









Resistivity Logs  All
Types  Tracks 2 + 3 






RESD 
Deep Resistivity 
0.2 
2000 
ohmm 
Log 
Red 
2 
Long Dash 
RESM 
Medium Resistivity 
0.2 
2000 
ohmm 
Log 
Blue 
2 
Short Dash 
RESS 
Shallow Resistivity 
0.2 
2000 
ohmm 
Log 
Black 
2 
Solid 
** RESxxx 
Optional eg Array RES 
0.2 
2000 
ohmm 
Log 
Blue 
1 
Dot Dash 









Sonic Logs  All Types
 Tracks 2 + 3 






DTC 
Compressional Travel Time 
500 
100 
ms/m 
Linear 
Blue 
2 
Solid 
DTS 
Shear Travel Time 
500 
100 
ms/m 
Linear 
Green 
2 
Solid 
DTC 
Compressional Travel Time 
140 
40 
ms/ft 
Linear 
Blue 
2 
Solid 
DTS 
Shear Travel Time 
140 
40 
ms/ft 
Linear 
Green 
2 
Solid 
** DTxxx 
Optional eg dipole xy DT 
 
 
 
Linear 
 
2 
Long Dash 









Alternate for Low
Porosity Rocks 







Metric 








DTC 
Compressional Travel Time 
300 
100 
ms/m 
Linear 
Blue 
2 
Solid 
DTS 
Shear Travel Time 
300 
100 
ms/m 
Linear 
Green 
2 
Solid 
English 








DTC 
Compressional Travel Time 
100 
40 
ms/ft 
Linear 
Blue 
2 
Solid 
DTS 
Shear Travel Time 
100 
40 
ms/ft 
Linear 
Green 
2 
Solid 
** DTxxx 
Optional eg dipole xy DT 
 
 
 
Linear 
 
2 
Lomg Dash 









Density Neutron Logs 
All Types Tracks 2 + 3 






CDN Sand 








PHIN_SS 
Neutron Porosity 
0.60 
0.00 
fraction 
Linear 
Black 
2 
Long Dash 
PHID_SS 
Density Porosity 
0.60 
0.00 
fraction 
Linear 
Red 
2 
Solid 
PEF 
Photoelectric Effect 
15 
+5 
cu 
Linear 
Purple 
2 
Dot Long Dash 
DCOR 
Density Correction 
750 
250 
kg/m3 
Linear 
Black 
2 
Short Dash 









CDN Carb 








PHIM_LS 
Neutron Porosity 
0.45 
0.15 
fraction 
Linear 
Black 
2 
Long Dash 
PHID_LS 
Density Porosity 
0.45 
0.15 
fraction 
Linear 
Red 
2 
Solid 
PEF 
Photoelectric Effect 
0 
20 
cu 
Linear 
Purple 
2 
Dot Long Dash 
DCOR 
Density Correction 
250 
750 
kg/m3 
Linear 
Black 
2 
Short Dash 









USA Sand 








PHIN_SS 
Neutron Porosity 
0.60 
0.00 
fraction 
Linear 
Black 
2 
Long Dash 
DENS 
Density 
1.65 
2.65 
g/cc 
Linear 
Red 
2 
Solid 
PEF 
Photoelectric Effect 
15 
+5 
cu 
Linear 
Purple 
2 
Dot Long Dash 
DCOR 
Density Correction 
0.75 
0.25 
g/cc 
Linear 
Black 
2 
Short Dash 









USA Carb 








PHIN_LS 
Neutron Porosity 
0.45 
0.15 
fraction 
Linear 
Black 
2 
Long Dash 
DENS 
Density 
1.95 
2.95 
g/cc 
Linear 
Red 
2 
Solid 
PEF 
Photoelectric Effect 
0 
20 
cu 
Linear 
Purple 
2 
Dot Long Dash 
DCOR 
Density Correction 
0.25 
0.75 
g/cc 
Linear 
Black 
2 
Short Dash 









Composite Log  Basic
Raw Data  4 Track Grid 






Correlation 
Track 1 







Resistivity 
Track 2 







Sonic 
Track 3 







Density Neutron 
Track 4 







Log curves as defined in each individual log description



































DEFAULT PLOT LAYOUT EXAMPLES
Typical resistivity log (left) and sonic log (right) displayed on
traditional log tracks. Correlation curves in Track 1 to the left of
the depth track and specific log curves in Tracks 2 +3.
Shading on sonic log indicates bad data caused by fractures.
Density neutron PE log on Limestone scale (left) and same log
displayed on Dolomite scale (right). Red shading indicates density
neutron crossover which could indicate light hydrocarbons OR
limestone. PE curve indicates pure dolomite so crossover shows gas
or very light oil.
Composite plot in this example combines correlation and resistivity
tracks, with porosity,
saturation, permeability, and lithology results tracks.
