TGS- GPS LAS Guidelines flyer.

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© 2015 TGS-NOPEC Geophysical Company ASA. All rights reserved.
Well Integrity Validation
ƒƒ Well information will be verified for accuracy.
ƒƒ Logs will be checked for quality and coverage before digitizing for
borehole recognition
Data capture
ƒƒ A standard LAS file will consist of one gamma ray, spontaneous
potential, caliper, resistivity (shallow, medium, and deep) all sonic,
and density (bulk, correction, and neutron/density porosity, PE).
ƒƒ Additional logs such as micro, and dipmeter are considered
non-standard but can be added upon request for an
additional charge.
ƒƒ Mud logs are available as separate LAS file. See your account
manager for details.
Resistivity
Three curves from a resistivity log will be processed – “shallow, medium
and deep resistivity”.
Sonic
All sonic curves are processed.
FDC/CNL
One of each of the shared curves (GR, Cali and SP) in priority as follows:
LAS Guidelines - US
Data Processing
ƒƒ Data values in casing will be removed (except GR and NPHI).
ƒƒ Data values below first reading will be removed.
ƒƒ -999.25 will be inserted for all removed data values.
ƒƒ Negative values on resistivity will be set at .0004.
ƒƒ Negative values on GR will be clipped to 0.
ƒƒ Negative values on DT will be clipped to 0.
ƒƒ Curves with the same curve name/description will be merged into
one continuous curve covering the entire depth available.
ƒƒ In case of overlapping runs, shallower runs at first reading will be
merged to subsequent deeper runs.
ƒƒ All processed curves will retain the original logging contractor
mnemonics.
ƒƒ Header information will be captured for the last run.
ƒƒ Stacked Header on request.
ƒƒ All LAS is subject to a rigorous quality control process to ensure
both complete curve coverage and a match between the digits and
the image.
ƒƒ With direct correlation, curves such as DPHI and RHOB, and
resistivity and conductivity are overlaid to ensure accurate
digitizing.
Final Data Output
ƒƒ LAS file will be output in LAS version 2.0.
ƒƒ All raw LAS will be output at .5 samples per feet unless metric
which will be output at .1 samples per feet.
ƒƒ Log header parameters and information will be provided in the
LAS file for the last run available.
ƒƒ Data delivery is available on LOG-LINE Plus!®
or via FTP/Internet.
Curve Type Digitizing priority #
Most Continuous Res.
FDC/
CNL
Sonic
Gamma Ray “GR” 1 4 2 3
Caliper “CALI” 1 4 2 3
Spontaneous poten-
tial”SP”
1 2 4 3
Curve Type Example
Bulk Density RHOB, RHBB...
Density Correction DRHO, CORR, DRBB...
Neutron Porosity NPHI, NPOR, CNC, CNF...
Density Porosity DPHI...
Curve Type Example
Delta DT, DTL...
Curve Type Range Example
Shallow ~10”, 20” ASN, AT10, ASFL
Medium ~30” ILM, AT30
Deep ~60”, 90” ILD, AT90
Deep ~8’, 18’ LAT
LAS Coverage Map