PREFACE

• This standard was prepared by the API Subcommittee on Recommended Format for Digital Well Log Data. The content is based on a concept and proposal originally submitted to API by Schlumberger Well Services. This publication was under jurisdiction of the American Petroleum Institute Production Department's Executive Committee on Drilling and Production Practices until June 1998, when Petrotechnical Open Software Corporation (POSC) accepted its stewardship.
• This publication specifies a format for digital well log data, called here the Digital Log Interchange Standard (DLIS). This format may be used for the recording of well log data on magnetic tape as well as on other storage media.
• Anyone may use this standard who desires to do so, subject to the terms of the POSC Software License Agreement.
• Suggestions for revisions or additions are invited and should be submitted to POSC.
• Requests for permission to reproduce any part of the material published herein shall be addressed to POSC.

SPECIAL NOTES

ORGANIZATION

Structure: How Is This Document Organized?

Chapter 1:

INTRODUCTION

Chapter 2:

DATA ORGANIZATION, a description of the physical and logical hierarchies, their organizations and relationships

Chapter 3:

LOGICAL RECORD SYNTAX, a description of how logical records are represented

Chapter 4:

SEMANTIC TERMINOLOGY AND RULES, a summary of important concepts and general rules for defining elements of the standard

Chapter 5:

SEMANTICS: STATIC AND FRAME DATA, a description of Frames, the Objects required to define them, and the Objects which establish the parameters and environment for processing Frames

Chapter 6:

SEMANTICS: TRANSIENT DATA, a description of the Objects that convey messages and signify changes during acquisition and processing of Frames

Chapter 7:

SEMANTICS: DICTIONARIES, a description of the Objects that specify the semantic structure of the standard and that specify dictionary-controlled names used by the standard

Appendix A:

LOGICAL RECORD TYPES, a list of defined Types for Public and Private Logical Records

Appendix B:

REPRESENTATION CODES, a list of Representation Codes

Appendix C:

PROPERTY INDICATORS, a list of indicators used to designate the processing or corrections performed on data

Appendix D:

CHANGEABLE ATTRIBUTES, a list of those defined Attributes that are permitted to be changed (i.e., updated) in a Logical File

Appendix E:

CHECKSUM ALGORITHM, a description of the algorithm used to compute the Checksum in the Logical Record Segment Trailer.

Appendix F:

UNIT SYMBOLS, a list of symbols for base units and selected derived units

Glossary

Notation: How Is This Document Written?

Acronyms are fully defined before they are used.

Many figures include comment numbers that associate a particular item with a comment that appears below the figure. For example,

Figure 5-25. Attributes of Group Object

Label	Restrictions	Comments
DESCRIPTION	C = 1, R = ASCII	-
OBJECT-TYPE	C = 1, R = IDENT	1
OBJECT-LIST	R = (OBNAME, OBJREF)	2
GROUP-LIST	R = OBNAME	3

Comments:

 
1. The OBJECT-TYPE Attribute specifies ...
 
2. The OBJECT-LIST Attribute is a List of references to ...
 
3. The GROUP-LIST Attribute is a List of references to ...

Trademarks

The following is a mark of Schlumberger:

Schlumberger

The following is a mark of Digital Equipment Corporation:

VAX

The following is a mark of AT&T:

UNIX

The following is a mark of IBM:

IBM