Plotting Wireline Data

Aside from the LogPass (the data structure that holds the frame data) the plot layout needs to be specified. There are two ways that TotalDepth does this:

• A plot specification that is integral to the file. For example; LIS files may well have FILM and PRES tables within them that configure the plot as the recording engineer (or software) intended. In this case TotalDepth can make those plots directly.
• A plot specification that is specified externally to the file. TotalDepth supports one such way; using LgFormat XML files and these are described below.

Wireline Files With Integral Plot Data

This applies to LIS (and possibly RP66 files). The LAS file specification does not describe any plot specification at all.

LIS Plot Specification

There are a number of table-like Logical Records (type 34) within a Log Pass that can specify the plot layout. As a minimum TotalDepth.LIS needs a FILM and a PRES record.

FILM Record

A dump of a FILM Logical Record might look like this:

Table record (type 34) type: FILM

MNEM  GCOD  GDEC  DEST  DSCA
-----------------------------

1     EEE   ----  PF2   D200
2     E4E   -4--  PF1   DM

The columns are:

Column	Description
MNEM	The (logical) name of the output, TotalDepth uses this as part of the plot file name.
GCOD	The coding of the tracks. E4E means three tracks which have linear, log (4 decades), linear. With three tracks the X axis track (depth for example) appears between the first and second tracks.
GDEC	The number of logarithmic decades for each track, - for linear.
DEST	The physical destination (in the logging unit) of the plot. Ignored.
DSCA	The depth scale, encoded. For example D200 means 1:200.

PRES Record

A dump of a PRES Logical Record might look like this:

 Table record (type 34) type: PRES

MNEM  OUTP  STAT  TRAC  CODI  DEST  MODE      FILT          LEDG          REDG
-----------------------------------------------------------------------------------

SP    SP    ALLO  T1    LLIN  1     SHIF      0.500000      -80.0000       20.0000
CALI  CALI  ALLO  T1    LDAS  1     SHIF      0.500000       5.00000       15.0000
MINV  MINV  DISA  T1    LLIN  1     SHIF      0.500000       30.0000       0.00000
MNOR  MNOR  DISA  T1    LDAS  1     SHIF      0.500000       30.0000       0.00000
LLD   LLD   ALLO  T23   LDAS  1     GRAD      0.500000      0.200000       2000.00
LLDB  LLD   ALLO  T2    HDAS  1     GRAD      0.500000       2000.00       200000.
LLG   LLG   DISA  T23   LDAS  1     GRAD      0.500000      0.200000       2000.00
LLGB  LLG   DISA  T2    HDAS  1     GRAD      0.500000       2000.00       200000.
LLS   LLS   ALLO  T23   LSPO  1     GRAD      0.500000      0.200000       2000.00
LLSB  LLS   ALLO  T2    HSPO  1     GRAD      0.500000       2000.00       200000.
MSFL  MSFL  ALLO  T23   LLIN  1     GRAD      0.500000      0.200000       2000.00
11    DUMM  DISA  T1    LLIN  NEIT  NB        0.500000       0.00000       1.00000
12    DUMM  DISA  T1    LLIN  NEIT  NB        0.500000       0.00000       1.00000
...

Column	Description
MNEM	The (logical) name of the output curve. Note multiple curves might come from one OUTP.
OUTP	The source of the curve.
STAT	Status, is this curve to be plotted.
TRAC	Which track the curve should be plotted on.
CODE	The line coding, dot, dash etc.
DEST	The logical film that this curve is sent to. Can be BOTH and so on.
MODE	What to do when the curve goes off scale (wrap round the track for example).
FILT	Filtering. Unused.
LEDG	Value of the left edge of the plot.
REDG	Value of the right edge of the plot.

Records Needed for a LIS Plot

As a minimum TotalDepth needs a FILM and PRES plot, using these TotalDepth can produce a plot identical to that when the data was recorded.

In future releases TotalDepth might also support these Logical Records for plotting:

• AREA: Describes shading between curves on a plot.
• PIP: Describes integration marks on the plot such as integrated transit time, integrated hole volume etc.
• VDL: Describes presentation of waveform amplitude data.

Wireline Files With External Plot Data

This can apply to any wireline file and it means using an external configuration file to decide the plot layout. For example; LAS files do not have any plot specification (the LAS standard precludes this). The presentation of the plot is made with an external plot specification.

These external plot specifications are numerous and varied. TotalDepth currently supports one such specification: the XML LgFormat or LgSchema files.

LgFormat XML Files

These appear to originate from some of Schlumberger’s “free” software.

Here is an example LgFormat XML file for plotting HDT logs .TotalDepth supplies an number of examples of these.

There are a number of problems [1] with the LgFormat which is why TotalDepth only supports a subset of it while we look for something better.

Footnotes

[1]

For example the LgCurve element content of <LeftLimit> and <RightLimit> is numeric, without units. This robs a compliant implementation of the opportunity of converting frame data, say in "V/V " to plot data say "PU  " which might be far more appropriate. Truth in advertising prompts me to say that LIS PRES tables have the same flaw but they have a reasonable excuse that they are per file specification rather than a global specification.