====== LAS file support in GS3D ======

==== Minimum LAS file example ====

{{:tutorials:adddata:6169b3ae0a3e6609e21b6032ae3b92e3.png}}

• Well section **requires NULL, X, Y** values between a “.” and a “:”’ e.g
<code>
     NULL. -999.999 :

</code>

• Well section **identifiers are upper case** e.g. NULL

• Well section **option: WELL**, the name of the log
<code>
     WELL. My well log :

</code>

• Curve section with names of the data columns. **There must be as many names as data columns**. In this example there are two names: Depth and Induction, and exactly two data columns.
<code>
     Depth.m :\\
     Induction.mS/m :

</code>

• The first data **column must be depth/elevation values**.\\
\\
• Data section **values are separated with space character**. There can be one or more spaces between values. The space character is the only valid separator!\\
\\
• Data section **decimal separator is dot**: “.”
==== Copy paste example: ====

~Well\\
NULL. -999.999 :\\
X. 566526.9514 :\\
Y. 6360814.298 :\\
~Curve\\
Depth.m :\\
Induction.mS/m :\\
~ASCII\\
0.9 102.392\\
0.95 78.087\\
1 70.554

==== LAS 2.0 format description from this link: ====

[[http://www.cwls.org/wp-content/uploads/2014/09/LAS_20_Update_Jan2014.pdf|http://www.cwls.org/wp-content/uploads/2014/09/LAS_20_Update_Jan2014.pdf]]

• A LAS file is a structured ASCII file containing log curve data and header information. The header information is located at the beginning of the file and followed by curve data.\\
\\
• The standard was designed to simplify the exchange of digital log data between users.\\
\\
• The LAS format is intended for optically presented log curves although other curves may also be included.\\
\\
• The ASCII character set is limited to ASCII 13 (carriage return), ASCII 10 (line feed), and ASCII 32 to ASCII 126 inclusive. All other ASCII characters are not allowed, and it is suggested that software readers convert them to a space (removing them may cause issues if the character was intended to represent a space such as the tab character). Line termination will consist of ASCII 13 ASCII 10 (CR LF) except for the last line.\\
\\
• Each LAS 2.0 file contains only one continuous interval in the data section. For example, a repeat section would make up one file and the main pass another.\\
\\
• LAS files end in ".LAS" so that they can be easily recognized.\\
\\
• Each LAS file consists of sections. Sections begin with a header line defined as beginning with the ~ tilde character when it occurs as the first non-space character on a line. The character immediately following the tilde character defines the section with the remainder of the line being ignored. The characters "V", "W", "C", "P", "O", and "A" are reserved in the LAS 2.0 standard. The sections defined by the LAS 2.0 standard are limited to one occurrence per file. Customer defined sections are permitted but must be located after the first section (~V) and before the last section (~A).\\
\\
• The sections defined for the LAS 2.0 standard are as follows:

- "~V" (also known as "~VERSION INFORMATION SECTION") is a required section; has formatting requirements; must be the first section; identifies the version number and whether data is in "wrapped" or "un-wrapped" mode.

- "~W" (also known as "WELL INFORMATION SECTION") is a required section; has formatting requirements; is preferably the second section; contains information on the well name, location, and start and stop values of the data in this file.

- "~C" (also known as ~CURVE INFORMATION SECTION") is a required section; has formatting requirements; contains curve mnemonics and their definitions in the order that they appear in the data section.

-"~P" (also known as ~PARAMETER INFORMATION SECTION") is an optional section; has formatting requirements; contains information on parameters or constants relevant to the wellbore such as mud resistivity, wireline engineer, truck number etc.

-"~O" (also known as "~OTHER") is an optional section; has no formatting requirements; contains other information or comments.

- "~A" (also known as ~ASCII LOG DATA") is a required section; has formatting requirements; is the last section in the file and also referred to as the data section. The index of the data columns is either Depth or Time. The index values always appear in the first column and each column of data must be separated by at least one space (ASCII 32). All values in the ASCII log data section must be floating point or integer (long) values. Other formats such as Text or Exponential values are not supported.

• Two flags are used in LAS files: 1) "#" signifies a comment line when used as the first non-space character on a line and 2) "~" signifies the beginning of a section when used as the first nonspace character on a line.\\
\\
• The sections "VERSION", "WELL", "CURVE" and "PARAMETER" use line delimiters. The delimiters are: 1) first dot in a line 2) first space after the first dot in a line and 3) the last colon in a line.