LAS20_Standards.txt

LAS VERSION 2.0                                         September 25, 1992

A FLOPPY DISK

STANDARD FOR LOG DATA


BY

Canadian Well Logging Society, Floppy Disk Committee
Suite 229,  640 - 5 Avenue, S.W.
Calgary, Alberta  T2P 0M6
Canada


ABSTRACT

The Canadian Well Logging Society's Floppy Disk Committee has designed 
a standard  format for log data on floppy disks. It is known as the LAS 
format (Log ASCII Standard). LAS consists of files written in ASCII 
containing minimal header information and is intended for optically 
presented log curves. Details of the LAS format are described in this 
paper.

The purpose of the LAS format is to supply basic digital log data to users 
of personal computers in a format that is quick and easy to use.


INTRODUCTION

Log analysts who use personal computers have, in the past, been entering 
log data into their machines mainly through a hand digitizing procedure 
because most personal computers are unable to handle data from magnetic 
tapes.  The industry was beginning to address this inefficiency by making 
log data available on floppy disks in a variety of formats. It was at this 
point that the Canadian Well Logging Society set up the Floppy Disk 
Committee to design a standard for log data on floppy disks that would meet 
the needs of personal computer users.

Various standards for digital well log data already exist.  The LIS format 
(Log Information Standard) is one of the more popular standards. A more 
complete standard has been designed by the American Petroleum 
Institute and is known as the DLIS format (Digital Log Interchange 
Standard).  Both of these standards are very useful but because of their 
completeness, and resulting complexity, they do not address the needs of 
most personal computer users.

Users of personal computers have serious space limitations and are normally 
only interested in the optically presented curves. They also want to get 
this data into their machines quickly and easily. The LAS format addresses 
these needs and can be compared to a "Reader's Digest" version of the LIS 
or DLIS formats.  If more detailed log information is required, then the 
LIS or DLIS format should be used.  The LAS format is intended to complement 
the LIS or DLIS formats as each has its own specific purpose.



GENERAL DESCRIPTION

The LAS format was designed to be easily understood by the user and at the 
same time contain enough flags to assist the programmer. The LAS format 
must always be written in ASCII. If it is written using a compression 
routine, in binary, or in any other form, an executable program must exist 
on the floppy disk that will convert the file back to LAS format.

The LAS format consists of files. For example, a repeat section would make 
up one file and the main pass another. Each of the file names end in ".LAS" 
so that they can be easily recognized. An individual floppy disk must not 
contain partial files that continue onto a second floppy disk. Large files 
that do not fit on one floppy must be split into two or more files.

Each file consists of numerous sections. These sections are not order 
specific except that the last section must always be the data section. 
The first section is usually the "VERSION" section containing the version 
number of the LAS format and identifies whether the data is in wrap mode.  
The "WELL INFORMATION" section contains information on the well name, 
location, and the start and stop depths of the data in this file.  The 
"CURVE INFORMATION" section contains the curve mnemonics, units used, and 
the definitions of these mnemonics, in the order that they appear in the 
data section.  The "PARAMETER" section contains information on parameters 
or constants (such as mud resistivities) and is optional.  The "OTHER" 
section is also optional and contains any other information or comments.  
The last section is always the "ASCII LOG DATA" section.  Depth values 
normally appear in the first column and each column of data must be separated 
by a space. 

More detailed LAS format specifications can be found in the Appendix.


REFORMAT AND CERTIFY PROGRAMS

To assist users of LAS formatted data, a program was written to modify 
LAS files into forms that may be more compatible to the user's needs. 
The program called REFORMAT performs the following tasks: 

     1) Extract a specific depth interval

     2) Extract specific curves

     3) Reverse depth direction

     4) Change sampling interval

     5) Convert wrap mode to unwrap mode

     6) Scan for non-standard characters which may cause difficulties 
       in some programs.

     7) Convert LAS version 1.2 to version 2.0

The CERTIFY program was designed to verify that files meet the LAS 
standard. If the LAS standards are not met, it will identify the errors.  
In case of disagreement between this program and the printed LAS standard 
document, the document will be deemed to be correct.  The CERTIFY program 
also includes documentation on the LAS standard.

The REFORMAT  and CERTIFY programs were written by Robin Winsor of Gulf 
Canada Resources Ltd. in ANSI standard "C" and compiled with a Microsoft 
C 5.1 compiler.  These programs are not part of the LAS standard. 

The author of these programs does not reserve any rights and does not 
warrant the program for any specific purpose.  An LAS information package 
is available for $10.00 through the C.W.L.S.  The package includes an 
executable form of the REFORMAT and CERTIFY programs, source code for 
REFORMAT, and two test LAS files on a 3.5 inch 720K DOS compatible floppy 
disk.

The address is as follows:

   Canadian Well Logging Society
   #229, 640 - 5 Avenue, S.W.
   Calgary,  Alberta
   CANADA  T2P 0M6


CONCLUSIONS

The latest version of the LAS standard is version 2.0 which first became 
available in September 1992.  The CWLS Floppy Disk Committee will continue 
to monitor the LAS standard to address problems and make modifications as 
required. Feedback concerning the user's likes or dislikes would be greatly 
appreciated and should be sent to the CWLS to the attention of the Floppy 
Disk Committee.

It is hoped that by creating the LAS, more widespread use will be made
of digital log data.











APPENDICES


Appendix 1      -       LAS Format Specifications for Version 2.0

Appendix 2      -       Example LAS Files

Appendix 3      -       REFORMAT Program

Appendix 4      -       CERTIFY Program 

Appendix 5      -       Updates











APPENDIX 1

LAS FORMAT SPECIFICATIONS FOR VERSION 2.0


PART  1 GENERAL DESCRIPTION

- The LAS Format is designed to store log data on floppy disks. This 
standard is intended to simplify the exchange of digital log data between 
users. The general specifications of this format are as follows:

- The floppy disk size, type, or density is not specified because 
conversion between them is straightforward.

- It is the intent of this standard to store optically presented log 
curves although other curves may also be stored. Raw count rates, wave 
form data etc. are more efficiently stored on magnetic tape using LIS 
or DLIS format.

- Floppy disks in the LAS format must be MS/DOS or PC/DOS compatible

- The file must be written in ASCII.  If the file is written using a 
compression routine, in binary, or in any other form, an executable program  
must  exist on the floppy to convert it back to LAS format.

- An individual floppy disk must not contain partial files that continue 
onto a second floppy. Large files that do not fit onto one floppy must 
be split into two or more separate files.  This may be achieved by 
splitting the curves or segmenting the depths.

- All files in LAS format must end in ".LAS" so that they may be easily 
recognized.

- The LAS format is a minimum standard. It is expected that most users 
and suppliers will exceed this minimum standard.


PART  2         MAJOR COMPONENTS OF AN LAS FILE

- Each LAS file contains numerous sections and each section begins with a 
tilde (~) mark. The last section in an LAS file must always be the log 
data section.

- The sections that make up an LAS file are as follows:

~V   - contains version and wrap mode information
~W   - contains well identification
~C   - contains curve information
~P   - contains parameters or constants (this section is optional)
~O   - contains other information such as comments (this section is optional)
~A   - contains ASCII log data

- These sections are described in more detail in part four of this appendix.



PART  3 FLAGS

Flags are used to assist computers in identifying specific lines in a file. 
The following flags are used in the LAS format:

"~" (tilde): The ASCII equivalent of this flag is decimal 126 or hexadecimal 
   7E. This flag when used will be the first non-space and non-quotation 
   character on a line. It is used to mark the beginning of a section 
   in a file. The first letter directly after the tilde identifies 
   the section. (See part two.)  All upper case letters in the space 
   following a tilde mark are reserved for use by the committee. 
   The remainder of the line will be treated as comments.

"#" (pound): The ASCII equivalent of this flag is decimal 35 or hexadecimal 
   23. This flag when used will be the first non-space and non-quotation 
   character on a line. The pound sign is used to indicate that the 
   line is a comment line. Comment lines can appear anywhere above the 
   ~A section.

"." and ":" : In the "Version", "Well", "Curve", and Parameter", sections 
   the dots, colons, and spaces are used to delimit the information 
   within the line. each non-comment line in these sections must 
   contain one dot and one colon and have their lines laid out as 
   follows:

   MNEM.UNITS        DATA         :DESCRIPTION OF MNEMONIC


Where   MNEM = mnemonic. This mnemonic can be of any length but must not 
   contain any internal spaces, dots, or colons. Spaces are permitted 
   in front of the mnemonic and between the end of the mnemonic and 
   the dot.

   UNITS = units of the mnemonic (if applicable). The units if used,
   must be located directly after the dot. There must be no spaces 
   between the units and the dot. The units can be of any length 
   but must not contain any colons or internal spaces.

   DATA = value of, or data relating to the mnemonic. This value or 
   input can be of any length and can contain spaces or dots as 
   appropriate, but must not contain any colons. It must be 
   preceded by at least one space to demarcate it from the units 
   and must be to the left of the colon.

   DESCRIPTION = description or definition of the mnemonic. It is 
   always located to the right of the colon. Its length is limited 
   by the total line length limit of 256 characters which includes 
   a carriage return and a line feed.


PART  4         DETAILS

The actual format for each of the sections discussed in this part of the 
paper is best understood by looking at the examples in the boxed areas. 
The exact spacing is not critical because computer programs will use the 
dots, colons, and spaces to decipher each line. 






~V (Version Information)

-This section is mandatory and usually appears at the very beginning of 
the  file.

-It identifies which version of the LAS format is being used and whether  
wrap mode is used.

-This section must contain the following lines:

"VERS.    2.0 : CWLS LOG ASCII STANDARD - VERSION 2.0"
   Refers to which version of LAS was used.

"WRAP.   YES   : Multiple lines per depth step"
   OR 
"WRAP.   NO    :  One line per depth step"
   Refers to whether a wrap around mode was used in the data section.  
   If no wrap mode is used the line will have a maximum length of 256 
   characters (including the carriage return and line feed). If wrap 
   mode is used the depth value will be on its own line and all lines 
   of data will be no longer than 80 characters (including carriage 
   return and line feed).

-Additional lines in the version section are optional.


-The following is an example of a Version Information Section.
-----------------------------------------------------------------------------
~Version Information Section
VERS.           2.0     :   CWLS log ASCII Standard -VERSION 2.0
WRAP.           NO      :   One line per depth step
-----------------------------------------------------------------------------


~W (Well Information)

-This section is mandatory.

-It identifies the well, its location and indicates the start and stop 
depths of the file.

-This section must contain the following lines with the mnemonics as 
indicated:

"STRT.M           nnn.nn   : START DEPTH"
   Refers to the first depth in the file. The "nnn.nn" refers to the 
   depth value. The number of decimals used is not restricted. The 
   ".M" refers to metres and can be replaced when other units are 
   used. The start depth can be either greater or less than the stop 
   depth.




"STOP.M           nnn.nn   : STOP DEPTH"
   Refers to the last depth in the file. The "nnn.nn" refers to the 
   depth value. The number of decimals used is not restricted. The 
   ".M" refers to metres and can be replaced when other units are 
   used.



"STEP.M           nnn.nn   : STEP"
   Refers to the depth increment used. A minus sign must precede the 
   step value if the start depth is greater than the stop depth 
   (ie, from TD to casing has a minus step value). A step value of 
   zero indicates a variable step.

"NULL.            nnnn.nn  : NULL VALUE"
   Refers to null values.  Two common ones in use are -9999 and -999.25.

"COMP.   aaaaaaaaaaaaaaaaaaaaa   : COMPANY"
   Refers to company name.

"WELL.   aaaaaaaaaaaaaaaaaaaaa   : WELL"
   Refers to the well name.

"FLD. aaaaaaaaaaaaaaaaaaaaa   : FIELD"
   Refers to the field name.

"LOC. aaaaaaaaaaaaaaaaaaaaa   : LOCATION"
   Refers to the well location.

"PROV.   aaaaaaaaaaaaaaaaaaaaa   : PROVINCE"
   Refers to the province. For areas outside Canada this line may be 
   replaced by:
"CNTY.   aaaaaaaaaaaaaaaaaaaaa   : COUNTY"
"STAT.   aaaaaaaaaaaaaaaaaaaaa   : STATE"
"CTRY.   aaaaaaaaaaaaaaaaaaaaa   : COUNTRY"

"SRVC.   aaaaaaaaaaaaaaaaaaaaa   : SERVICE COMPANY"
   Refers to logging company.

"DATE.   aaaaaaaaaaaaaaaaaaaaa   : DATE"
   Refers to date logged.

"UWI .   aaaaaaaaaaaaaaaaaaaaa   : UNIQUE WELL ID"
   Refers to unique well identifier. (See References.)  For areas 
   outside of Canada this may be replaced by:

"API .   aaaaaaaaaaaaaaaaaaaaa   : API NUMBER"

-Additional lines in the well information section are optional. There is no 
limit set on the number of additional lines.

-The following is an example of a Well Information Section in LAS version 2.0:
_____________________________________________________________________
~Well Information Section
#MNEM.UNIT      VALUE/NAME      DESCRIPTION
#--------     --------------   ---------------------
STRT.M          635.0000        :START DEPTH
STOP.M          400.0000        :STOP DEPTH
STEP.M          -0.125          :STEP 
NULL.           -999.25         :NULL VALUE
COMP.   ANY OIL COMPANY INC.            :COMPANY
WELL.   ANY ET AL 12-34-12-34           :WELL
FLD .   WILDCAT                         :FIELD
LOC  .  12-34-12-34W5M                  :LOCATION
PROV.   ALBERTA                         :PROVINCE 
SRVC.   ANY LOGGING COMPANY INC.        :SERVICE COMPANY
DATE.   13-DEC-86                       :LOG DATE
UWI .   100123401234W500                :UNIQUE WELL ID
_____________________________________________________________________

~C (Curve Information)

-This section is mandatory.

-It describes the curve and its units in the order they appear in the  
data section of the file.

-The mnemonics used are not restricted but must be defined on the line in 
which they appear.

-API codes are optional. (See References.)

-The curves described in this section must be present in the data set.

-The first curve described is normally depth.

- The units mnemonics if used must be directly to the right of the dot. No 
spaces must occur between the dot and the units mnemonic.



-The following is an example of a Curve Information Section with API codes.
-----------------------------------------------------------------------------------------------------
~Curve Information Section
#MNEM.UNIT           API CODE        Curve Description       
#----------        -----------    -------------------------------
DEPTH.M                        :  1       DEPTH
RHOB  .K/M3       45 350 02 00 :  2       BULK DENSITY
NPHI  .VOL/VO     42 890 00 00 :  3       NEUTRON POROSITY - SANDSTONE
MSFL  .OHMM       20 270 01 00 :  4       Rxo RESISTIVITY
SFLA  .OHMM       07 222 01 00 :  5       SHALLOW RESISTIVITY
ILM   .OHMM       07 120 44 00 :  6       MEDIUM RESISTIVITY
ILD   .OHMM       07 120 46 00 :  7       DEEP RESISTIVITY
SP    .MV         07 010 01 00 :  8       SPONTANEOUS POTENTIAL
GR    .GAPI       45 310 01 00 :  9       GAMMA RAY
CALI  .MM         45 280 01 00 :  10      CALIPER
DRHO .K/M3        45 356 01 00 :  11      DENSITY CORRECTION
-------------------------------------------------------------------------------------------------------


~P (Parameter Information)

-This section is optional. It defines the input values of various 
parameters relating to this well. These input values can consist of
numbers or words.

-The mnemonics used are not restricted but must be defined on the line on 
which they appear.

-There is no limit on the number of lines that can be used.




-The following is an example of a Parameter Information Section.
-----------------------------------------------------------------------------
~Parameter Information Section
#MNEM.UNIT                  Value                Description
#-----------------        ------------    ------------------------------
MUD  .                   GEL CHEM        :  Mud type
BHT  .DEG                114.0000        :  Bottom Hole Temperature
BS   .MM                 222.0000        :  Bit Size
FD   .K/M3               999.9999        :  Fluid Density
MDEN.K/M3                2650.0000       :  Logging Matrix Density
MATR .                   SAND            :  Neutron Matrix 
FNUM .                   1.0000          :  Tortuosity  Constant Archie's (a)
FEXP .                   2.0000          :  Cementation Exponent Archie's (m)
DFD  .K/M3               1200.0000       :  Mud Weight
DFV  .S                  50.0000         :  Mud Viscosity
DFL  .C3                 8.0000          :  Mud Fluid Loss
DFPH .                   10.0000         :  Mud pH
RMFS .OHMM               2.8200          :  Mud Filtrate Resistivity
EKB  .M                  566.9700        :  Elevation Kelly Bushing
EGL  .M                  563.6799        :  Elevation Ground Level
-----------------------------------------------------------------------------


~O (Other Information)

-This section is  optional. It is intended as a remarks or comments section.

-The following is an example of an "Other Information Section"
------------------------------------------------------------------------------------------------------------
~Other  Information Section
The log digits for this well were hand digitized from very poor half scale 
log  prints. This was the best information available at the time. Every 
attempt should be made to track down the original films.
.Dec. 12,1990  John Doe, Petrophysics
------------------------------------------------------------------------------------------------------------ 

~A (ASCII LOG DATA)

-The data section will always be the last section in a file.

-Each column of data must be separated by at least one space.

-A line of less than 256 characters (including a carriage return and line  
feed) will normally not be wrapped. Wrap mode will be used if the data is 
longer than 256 characters.

-In wrap mode, depth will be on its own line.

-In wrap mode, a line of data will be no longer than 80 characters. This 
includes a carriage return and line feed.

-If wrap mode is used, the decimal points should be aligned for ease of 
reading.

-Exponents are not permitted. The curve section can be used to overcome 
this limitation by changing the units.

REFERENCES

UWI codes : "Formation Water Resistivities of Canada", CWLS, 1987.

API codes : "Recommended Standard Format for Recording Digital Well Log
Data on Magnetic Tape", API - Bul. D-9, 3rd edition, 1981.



APPENDIX 2

EXAMPLE LAS FILES


EXAMPLE #1 - THE LAS STANDARD IN UNWRAPPED MODE

~VERSION INFORMATION
 VERS.                          2.0 :   CWLS LOG ASCII STANDARD -VERSION 2.0
 WRAP.                          NO  :   ONE LINE PER DEPTH STEP
~WELL INFORMATION 
#MNEM.UNIT              DATA                       DESCRIPTION
#----- -----            ----------               -------------------------
STRT    .M              1670.0000                :START DEPTH
STOP    .M              1660.0000                :STOP DEPTH
STEP    .M              -0.1250                  :STEP 
NULL    .               -999.25                  :NULL VALUE
COMP    .       ANY OIL COMPANY INC.             :COMPANY
WELL    .       ANY ET AL 12-34-12-34            :WELL
FLD     .       WILDCAT                          :FIELD
LOC     .       12-34-12-34W5M                   :LOCATION
PROV    .       ALBERTA                          :PROVINCE 
SRVC    .       ANY LOGGING COMPANY INC.         :SERVICE COMPANY
DATE    .       13-DEC-86                        :LOG DATE
UWI     .       100123401234W500                 :UNIQUE WELL ID
~CURVE INFORMATION
#MNEM.UNIT              API CODES                   CURVE DESCRIPTION
#------------------     ------------              -------------------------
 DEPT   .M                                       :  1  DEPTH
 DT     .US/M           60 520 32 00             :  2  SONIC TRANSIT TIME
 RHOB   .K/M3           45 350 01 00             :  3  BULK DENSITY
 NPHI   .V/V            42 890 00 00             :  4  NEUTRON POROSITY
 SFLU   .OHMM           07 220 04 00             :  5  SHALLOW RESISTIVITY
 SFLA   .OHMM           07 222 01 00             :  6  SHALLOW RESISTIVITY
 ILM    .OHMM           07 120 44 00             :  7  MEDIUM RESISTIVITY
 ILD    .OHMM           07 120 46 00             :  8  DEEP RESISTIVITY
~PARAMETER INFORMATION
#MNEM.UNIT              VALUE             DESCRIPTION
#--------------     ----------------      -----------------------------------------------
 MUD    .               GEL CHEM        :   MUD TYPE
 BHT    .DEGC           35.5000         :   BOTTOM HOLE TEMPERATURE
 BS     .MM             200.0000        :   BIT SIZE
 FD     .K/M3           1000.0000       :   FLUID DENSITY
 MATR   .               SAND            :   NEUTRON MATRIX
 MDEN   .               2710.0000       :   LOGGING MATRIX DENSITY
 RMF    .OHMM           0.2160          :   MUD FILTRATE RESISTIVITY
 DFD    .K/M3           1525.0000       :   DRILL FLUID DENSITY
~OTHER
     Note: The logging tools became stuck at 625 metres causing the data 
     between 625 metres and 615 metres to be invalid.
~A  DEPTH     DT    RHOB        NPHI   SFLU    SFLA      ILM      ILD
1670.000   123.450 2550.000    0.450  123.450  123.450  110.200  105.600
1669.875   123.450 2550.000    0.450  123.450  123.450  110.200  105.600
1669.750   123.450 2550.000    0.450  123.450  123.450  110.200  105.600



EXAMPLE #2 - ILLUSTRATING THE  LAS STANDARD WITH 
MINIMUM HEADER REQUIREMENTS IN UNWRAPPED MODE.


~V
VERS.                   2.0   :   CWLS log ASCII Standard -VERSION 2.0
WRAP.                   NO    :   One line per depth step
~W
STRT.M                          635.0000        :START DEPTH
STOP.M                          400.0000        :STOP DEPTH
STEP.M                          -0.1250         :STEP 
NULL.                           -999.25         :NULL VALUE
COMP.           ANY OIL COMPANY INC.            :COMPANY
WELL.           ANY ET AL 12-34-12-34           :WELL
FLD .           WILDCAT                         :FIELD
LOC .           12-34-12-34W5M                  :LOCATION
PROV.           ALBERTA                         :PROVINCE 
SRVC.           ANY LOGGING COMPANY INC.        :SERVICE COMPANY
DATE.           13-DEC-86                       :LOG DATE
UWI .           100123401234W500                :UNIQUE WELL ID
~C
DEPT    .M                              :   DEPTH
RHOB    .K/M3                           :   BULK DENSITY
NPHI    .VOL/VOL                        :   NEUTRON POROSITY - SANDSTONE
MSFL    .OHMM                           :   Rxo RESISTIVITY
SFLA    .OHMM                           :   SHALLOW RESISTIVITY
ILM     .OHMM                           :   MEDIUM RESISTIVITY
ILD     .OHMM                           :   DEEP RESISTIVITY
SP      .MV                             :   SPONTANEOUS POTENTIAL
~A
 635.0000     2256.0000   0.4033  22.0781 22.0781 20.3438 3.6660 123.4
 634.8750     2256.0000   0.4033  22.0781 22.0781 20.3438 3.6660 123.4



EXAMPLE #3 - ILLUSTRATING THE WRAPPED VERSION 
OF THE LAS STANDARD 


~VERSION INFORMATION
 VERS.                 2.0      :   CWLS log ASCII Standard -VERSION 2.0
 WRAP.                 YES      :   Multiple lines per depth step
~WELL INFORMATION 
#MNEM.UNIT                DATA                         DESCRIPTION
#----- -----           ----------           -----------------------------
STRT    .M               910.0000               :START DEPTH
STOP    .M               909.5000               :STOP DEPTH
STEP    .M               -0.1250                :STEP 
NULL    .                -999.25                :NULL VALUE
COMP    .       ANY OIL COMPANY INC.            :COMPANY
WELL    .       ANY ET AL 12-34-12-34           :WELL
FLD     .       WILDCAT                         :FIELD
LOC     .       12-34-12-34W5M                  :LOCATION
PROV    .       ALBERTA                         :PROVINCE 
SRVC    .       ANY LOGGING COMPANY INC.        :SERVICE COMPANY
SON     .       142085                          :SERVICE ORDER NUMBER
DATE    .       13-DEC-86                       :LOG DATE
UWI     .       100123401234W500                :UNIQUE WELL ID
~CURVE INFORMATION
#MNEM.UNIT                                    Curve Description
#---------                               ------------------------------
 DEPT   .M                              :    Depth
 DT     .US/M                           :  1 Sonic Travel Time
 RHOB   .K/M                            :  2 Density-Bulk Density
 NPHI   .V/V                            :  3 Porosity -Neutron
 RX0    .OHMM                           :  4 Resistivity -Rxo
 RESS   .OHMM                           :  5 Resistivity -Shallow
 RESM   .OHMM                           :  6 Resistivity -Medium
 RESD   .OHMM                           :  7 Resistivity -Deep
 SP     .MV                             :  8 Spon. Potential
 GR     .GAPI                           :  9 Gamma Ray
 CALI   .MM                             : 10 Caliper
 DRHO   .K/M3                           : 11 Delta-Rho
 EATT   .DBM                            : 12 EPT Attenuation
 TPL    .NS/M                           : 13 TP -EPT
 PEF    .                               : 14 PhotoElectric Factor
 FFI    .V/V                            : 15 Porosity -NML FFI
 DCAL   .MM                             : 16 Caliper-Differential
 RHGF   .K/M3                           : 17 Density-Formation
 RHGA   .K/M3                           : 18 Density-Apparent
 SPBL   .MV                             : 19 Baselined SP
 GRC    .GAPI                           : 20 Gamma Ray BHC
 PHIA   .V/V                            : 21 Porosity -Apparent
 PHID   .V/V                            : 22 Porosity -Density
 PHIE   .V/V                            : 23 Porosity -Effective
 PHIN   .V/V                            : 24 Porosity -Neut BHC
 PHIC   .V/V                            : 25 Porosity -Total HCC
 R0     .OHMM                           : 26 Ro
 RWA    .OHMM                           : 27 Rfa
 SW     .                               : 28 Sw -Effective
 MSI    .                               : 29 Sh Idx -Min
 BVW    .                               : 30 BVW
 FGAS   .                               : 31 Flag -Gas Index
 PIDX   .                               : 32 Prod Idx
 FBH    .                               : 33 Flag -Bad Hole
 FHCC   .                               : 34 Flag -HC Correction
 LSWB   .                               : 35 Flag -Limit SWB
~A Log data section
910.000000
  -999.2500  2692.7075     0.3140    19.4086    19.4086    13.1709    12.2681
    -1.5010    96.5306   204.7177    30.5822  -999.2500  -999.2500     3.2515
  -999.2500     4.7177  3025.0264  3025.0264    -1.5010    93.1378     0.1641
     0.0101     0.1641     0.3140     0.1641    11.1397     0.3304     0.9529
     0.0000     0.1564     0.0000    11.1397     0.0000     0.0000     0.0000
909.875000
  -999.2500  2712.6460     0.2886    23.3987    23.3987    13.6129    12.4744
    -1.4720    90.2803   203.1093    18.7566  -999.2500  -999.2500     3.7058
  -999.2500     3.1093  3004.6050  3004.6050    -1.4720    86.9078     0.1456
    -0.0015     0.1456     0.2886     0.1456    14.1428     0.2646     1.0000
     0.0000     0.1456     0.0000    14.1428     0.0000     0.0000     0.0000
909.750000
  -999.2500  2692.8137     0.2730    22.5909    22.5909    13.6821    12.6146
    -1.4804    89.8492   201.9287     3.1551  -999.2500  -999.2500     4.3124
  -999.2500     1.9287  2976.4451  2976.4451    -1.4804    86.3465     0.1435
     0.0101     0.1435     0.2730     0.1435    14.5674     0.2598     1.0000
     0.0000     0.1435     0.0000    14.5674     0.0000     0.0000     0.0000
909.625000
  -999.2500  2644.3650     0.2765    18.4831    18.4831    13.4159    12.6900
    -1.5010    93.3999   201.5826    -6.5861  -999.2500  -999.2500     4.3822
  -999.2500     1.5826  2955.3528  2955.3528    -1.5010    89.7142     0.1590
     0.0384     0.1590     0.2765     0.1590    11.8600     0.3210     0.9667
     0.0000     0.1538     0.0000    11.8600     0.0000     0.0000     0.0000
909.500000
  -999.2500  2586.2822     0.2996    13.9187    13.9187    12.9195    12.7016
    -1.4916    98.1214   201.7126    -4.5574  -999.2500  -999.2500     3.5967
  -999.2500     1.7126  2953.5940  2953.5940    -1.4916    94.2670     0.1880
     0.0723     0.1880     0.2996     0.1880     8.4863     0.4490     0.8174
     0.0000     0.1537     0.0000     8.4863     0.0000     0.0000     0.0000


EXAMPLE # 4  LAS FILE FOR TIME BASED DATA 

~VERSION INFORMATION
 VERS.                       2.0    :   CWLS LOG ASCII STANDARD -VERSION 2.0
 WRAP.                       NO     :   ONE LINE PER TIME STEP
#
~WELL INFORMATION 
STRT    .S      0.0000                           :START TIME 
STOP    .S      39.9000                          :STOP TIME
STEP    .S      0.3000                           :STEP
NULL    .       -999.25                          :NULL VALUE
COMP    .       ANY OIL COMPANY INC.             :COMPANY
WELL    .       ANY ET 12-34-12-34               :WELL
FLD     .       WILDCAT                          :FIELD
LOC     .       12-34-12-34W5                    :LOCATION
PROV    .       ALBERTA                          :PROVINCE 
SRVC    .       ANY LOGGING COMPANY INC.         :SERVICE COMPANY
DATE    .       13-DEC-86                        :LOG DATE
UWI     .       100123401234W500                 :UNIQUE WELL ID
#
~CURVE INFORMATION
 ETIM   .S               :  1  ELAPSED TIME
 BFR1   .OHMM            :  2  SINGLE PROBE 1 RESISTIVITY
 BSG1   .PSIG            :  3  SINGLE PROBE 1 STRAIN GAUGE PRESSURE 
#
~PARAMETER INFORMATION
MRT    .DEGC            67.0    : BOTTOM HOLE TEMPERATURE
GDEPT  .M               3456.5  : GAUGE DEPTH
DFD    .KG/M3           1000.0  : MUD WEIGHT
#
~A
0.0000          0.2125          16564.1445
0.3000          0.2125          16564.1445
0.6000          0.2125          16564.2421
0.9000          0.2125          16564.0434
1.2000          0.2125          16564.0430
1.5000          0.2125          16564.0435


                    




APPENDIX 4


REFORMAT PROGRAM
      
The REFORMAT program was designed to manipulate LAS formatted files into a 
form which may be more compatible with the user's needs. The REFORMAT 
program is not part of the LAS standard.

The REFORMAT program is capable of doing the following things:

1) Extract a depth interval
   - This allows the user to build a new LAS file covering a specific 
   depth interval of the input file. It works on unwrapped data only.

2) Extract one or more curves
   - This allows the user to build a new LAS file containing only the 
   curves specified by him. It will handle input data with lines up 
   to 1200 characters long. It works only on unwrapped data.

3) Reverse depth direction
   - Logs can be recorded from bottom to top or visa versa.  This 
   routine reverses the depth direction. It works on unwrapped data 
   only.

4) Change depth step (i.e. depth increment)
   - The depth step refers to the depth increment. This routine works 
   only on unwrapped data.

5) Convert wrap to unwrap mode
   - Wrap mode refers to the mode where the depth value is on its own 
   line and all of the curve data for that depth value are on the 
   lines that follow (see TEST02.LAS for an example). Unwrap mode 
   means there is only one line of curve data for each depth step 
   and the depth value is the first value in that line. This routine 
   converts wrapped data to the unwrapped mode provided that the 
   resulting lines are not longer than 1200 characters.

6) Scan for non-standard characters
   - Non ASCII or unprintable characters can cause difficulties to 
   some programs. This routine allows the user to find them and 
   delete them. 

7) Convert LAS version 1.2 to version 2.0


The REFORMAT program was written in ANSI standard 'C' and has been compiled 
   with Microsoft C5.1 compiler. The author of the program does not 
   reserve any rights and does not warrant the program for any 
   specific purpose. The executable as well as the code for REFORMAT 
   is included on the enclosed floppy disk.

   



APPENDIX 5

CERTIFY PROGRAM

The CERTIFY program was designed to read LAS files and establish whether 
all of the LAS specifications are being adhered to. This program also 
points out where the LAS specifications are not being followed

This program issues two types of messages. One is a "WARNING" and the 
other is a "FATAL ERROR". The "WARNING" is used to point out items that 
meet the LAS standard but could be improved upon to make the file more 
informative to the user. For example, if the "location" field in the Well 
Information Section is left blank the CERTIFY program will issue a WARNING. 
The "FATAL ERROR" message is issued on items that fail to meet the LAS 
specifications. For example if the "location" field is omitted from the 
Well Information Section, the CERTIFY program will issue a "FATAL ERROR" 
message.

The CERTIFY program is not part of the LAS Standard. It is being made 
available to assist the user in locating and identifying the most 
commonly occurring errors. 






APPENDIX 6

UPDATES


AUGUST 14,  1991

LAS        -version 1.2
REFORMAT   -version 2.0 (correcting errors in resampling and unwrap options)
CERTIFY    -version 1.0

APRIL 22,  1992

LAS        -version 1.2
REFORMAT   -version 2.0 
CERTIFY    -version 2.0   

MAY 18,  1992

LAS        -version 1.2
REFORMAT   -version 2.0 
CERTIFY    -version 3.0   (improve data section checking)

JUNE 8,  1992

LAS        -version 1.2
REFORMAT   -version 2.1 (fix minor bug in resample. Stop depth set correctly)
CERTIFY    -version 3.0  

SEPTEMBER 25,  1992

LAS        -version 2.0
REFORMAT   -version 2.2 (modified to handle LAS v 2.0)
CERTIFY    -version 3.1  (modified to handle LAS v 2.0)

MARCH 16, 1993

LAS        -version 2.0
REFORMAT   -version 2.3 (256 character header allowed when unwrapping)
CERTIFY    -version 3.2 (stricter ~ section and line length checks)

JUNE 11, 1993

LAS        -version 2.0
REFORMAT   -version 2.4 (minor bug fixes)
CERTIFY    -version 3.3 (minor bug fixes)  

NOVEMBER 7, 1993  (These and later versions require an 80286 processor or better.)

LAS        -version 2.0
REFORMAT   -version 2.41 (Improved end of file handling, minor bug fix.) 
CERTIFY    -version 3.4  (Complete data section checking, better end of file
                          handling and improved error reports.)        
                          
MARCH 23, 1994                                                            

CERTIFY    -version 3.5 (Fatal end of file condition changed to warning. Minor bug fixes.)




Please address any problems to:

CWLS Floppy Disk Committee
Suite 229,  640 - 5 Avenue, S.W.
Calgary, Alberta  T2P 0M6
CANADA