POSC PWLS V2.0 Reference Data Release
POSC Practical Well Log Standards
A Standard for Well Log Curve Classification
Revised and Expanded Results
||PWLS Revised and Expanded Results
PWLS Revised and Expanded
- Briefly, PWLS Version 2 is both a revision and expansion to Version
- Version 2 reflects the resolution of the dual classification issue
from Version 1.0.
- Version 2 is presented in a more structured way that identifies
clearly service company provided information versus industry-oriented,
- Version 2 includes additional service company tool/channel/curve data
and pseudo service company data defining PWLS curve mnemonics for oil
company calculated interpreted and composited curves.
- There are no substantive content changes between Versions 1.0 and 2
for acquisition curves. Version 2 includes POSC defined standard
mnemonics for joined (composite) and interpreted (processed) curve
Quick Access to the PWLS V2 Specifications
The formation of the Practical Well Log Standards (PWLS) was
motivated by several Well Log management business issues. Users have difficulty
finding the important Well Log data, because there are so many types of curves.
Names for both individual curves and collections of curves are complex and are
changing at an ever increasing rate. The lack of consistency over time is
confusing for experts and generalists alike. Until now, there has been no
recognized central source for Well Log naming standards. POSC organized the PWLS
project to establish and promulgate such standards for use throughout the
- Most of the business value of Well Log data is concentrated in a
relatively small number of types of curves. There are on the order of 50,000
visible acquisition curve types of which about 1,000 deliver the majority of
- The goal is to remove the mystery surrounding curve names caused by the
current proprietary and esoteric naming systems.
Tool names for acquisition data will maintain their full technical /
marketing names for continuity. Generic service class names are defined to
be understandable to all and to remain consistent over time. Specific tool
string names will be created by concatenating component tool names. [?]
Consider these Tool Type examples:
||Tool Type Descriptions
||Array Induction Resistivity
||Array Laterolog Resistivity
||Nuclear Magnetic Resonance
For curve names, the service company mnemonic is retained as the fundamental
Generic, cross-vendor classifications are defined to increase understandability and for
use in conducting processing activities. In Version 2, the curve classes are a
proper subset of an broadly defined hierarchy of Property Types. In addition,
each Property Type used to express a curve class is defined with a set of
characterizing attributes: object in which measurement is made (usually
formation), special measuring technique, basic property being measured, property
modifiers, and mathematical function applied to formulate the
Here are the same examples:
|Baker Atlas Curve Mnemonics
||Halliburton Curve Mnemonics
||Schlumberger Curve Mnemonics
|| Property Types
||Curve Class Attributes
|ATT1, ATT2, ...
||LSA1, LSA2, ..
||ISSA, STIK, ...
|CAL, CALX, ...
||HSI, SDK2, ...
||LCAL, RLCA, ...
|M2C1, M2C2, ...
||AIBC, AIFC, ...
||Property=Conductivity, Modifier=(Induction, Array)
||Property=Conductivity, Modifier=(Deep, Laterolog)
|BDCM, BDCX, ...
||RHOB, BD2, ...
||HDEB, HRHL, ...
The goal for V2 is to publish an effect set of specifications that
effectively supports the main purpose of PWLS, i.e. to support the
classification of well log curves that are commonly used by oil companies and to
use this classification as a tool to support general queries over large
populations of curves.
PWLS V2 carries forward the results published in V1 classifying the following
categories of logging tools from the participating service companies:
- Nuclear Tools
- Resistivity Tools
- Acoustic Tools
- Electromagnetic Propagation Tools
- Magnetic Resonance Tools
In addition, V2 includes recommended curve mnemonics for oil company produced
interpreted and composite curves. V2 also includes the structure to enable the
application of classification to high-level logging services, to computational
processes, and to log header parameter specifications.
PWLS V2 reflects the resolution of the dual classification approach adopted
in V1, eliminating the inherent ambiguity in that approach. This was
accomplished with the active encouragement and support of the PWLS Special
Interest Group, formed in 2002, and through the cooperation
of the participating service and software companies. The key concept used to
achieve this resolution was that the characteristics of a class are not and
should not be interpreted from the name of the class.
The technical work to formulate PWLS V2 was performed by the POSC staff with
support from participating organizations for consultation and, above all, for
company specific data. As mentioned, the encouragement to achieve an effective
and useful PWLS standard from the Special Interest Group was essential.
In parallel with the publication of PWLS V2, there is active dialogue in
progress with service and software vendors to ensure a common understanding, to
encourage and assist in the deployment of PWLS V2 in products and in oil company
data management procedures, and to ensure that service companies maintain a
complete and current flow of new and updated information to POSC.
The PWLS Special Interest Group is the formal user group for the PWLS
standard. As such, it will continue to highlight requirements and needs that
will be addressed by POSC and will influence future releases of the standard.
POSC is prepared to contribute and/or to organize resources, as necessary, to
expand the scope of PWLS classified well log curves. Some service companies are
comfortable taking the lead to select the high and medium value curves and to
determine the proper classification, i.e. Property Type and associated Curve
Class Attribute Values. In other cases, POSC will work with service companies
and oil companies to form expert groups that can perform this task. If there are
general technical issues that need consultation with a full cross-section of
service company and/or oil company support experts, then POSC will announce and
convene a technical working meeting for that purpose.
Another process undertaken by POSC is to consult with groups (inside or
outside the POSC community) that manage standards related to well log curve data
to ensure that the maximal beneficial value of using the PWLS standards is
understood, enabled, and encouraged.
Among the candidate subjects previously deemed worthy of future consideration
- Classify additional high and medium value acquisition curves currently in use
- Classify high and medium value acquisition curves for tools previously in use
- Classify historical acquisition tools
- Classify dipmeter/image tools
- Classify formation pressure tools
- Classify core data
- Classify deviation data (survey and interpolated)
- Classify mud log data
- Classify VSP data
Comments about this work may be directed to Jana Schey.
Last modified: September 25, 2003
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