Mapping Common Seismic Data Exchange formats to the PPDM Seismic Model Early Results

1
Mapping Common Seismic Data Exchange formats to
the PPDM Seismic Model - Early Results

• PPDM Spring Conference
• Pierre Fillon, BeGroup
• Jeffrey Pferd, Petris Technology

2
Objectives of Our Project

• Commitment to Standards
• Seismic Data Acquisition
• UKOOA P1/90
• SEG/P1
• PPDM Seismic Data Model
• Purpose of the overall project
• Establish a PPDM repository
• To load seismic data management system for
  navigation and survey information
• Provide web based GIS Interface
• Provide selection capability of survey and line
  details with export capability to UKOOA data
  files
• Link to seismic SEG-Y data and Tape Library
  references

3
Goals of this Paper

• Examples of the data mapping task
• Identify the issues that arose in the mapping
  effort
• Variables
• Logical model
• Documentation

4
Scope of Coverage

• 2D
• Survey identification
• Line identification
• Survey / Line link
• Location points vessel, etc.
• Points (with a spatial engine)
• 3D
• Survey identification
• Line identification
• Survey / Line link
• Location points vessel, etc.
• Receiver Points (with a spatial engine)

5
Reference Documents

• PPDM reference document is
• PPDM Relational Data Model Version 3.6 (October
  2001).
• UKOOA reference document is
• U.K.O.O.A. P1/90 post plot data exchange tape
  1990 format (June 1990).

6
Acquisition Standards

• A major difference between SEG/P1 and UKOOA is
  the better definition of the UKOOA header.
• PPM can handle navigation data both with and
  without the use of a spatial engine (like ESRI
  SDE or Oracle Spatial)
• PPDM table SEIS_POINT or
• PPDM table SEIS_SET_GEOMETRY which links the
  seismic line to a spatial object (vector).

7
2D Line identification Example

• Mandatory information for PPDM
• (PPDM SEIS_LINE.SEIS_SET_TYPE SEIS_LINE
  (subtype SEIS_LINE of type SEIS_SET)
• PPDM SEIS_LINE.SEIS_SET_ID unique ID
• Needs to be generated upon loading
• Main information
• PPDM SEIS_LINE.LINE_NAME UKOOA H0203 (Line
  prefix) UKOOA item 2 (Line name) // H0203 if
  other than N/A
• Concatenation and not applicable condition

8
Example of Mapping

• Geographic coordinate system used by the
  projection
• (120) PPDM ELLIPSOID.ELLIPSOID_ID unique id
• (121) PPDM ELLIPSOID.ELLIPSOID_NAME UKOOA H1500
  (Spheroid name)
• (122) PPDM ELLIPSOID.SEMI_MAJOR_AXIS UKOOA
  H1500 (a)
• (123) PPDM ELLIPSOID.INVERSE_FLATTENING UKOOA
  H1500 (1/f)
•  (124) PPDM GEODETIC_DATUM.GEODETIC_DATUM
  unique id
• (125) PPDM GEODETIC_DATUM.GEODETIC_DATUM_NAME
  UKOOA H1500 (Datum name)
• (126) PPDM GEODETIC_DATUM.ELLIPSOID (120)
•  (127) PPDM COORDINATE_SYSTEM.COORD_SYSTEM_ID
  unique id
• (128) PPDM COORDINATE_SYSTEM.COORD_SYSTEM_TYPE
  GEOGRAPHIC COORDINATE SYSTEM
•  (129) PPDM GEODETIC_TRANSFORM.TRANSFORM_ID
  unique id
• (130) PPDM GEODETIC_TRANSFORM.COORD_SYSTEM_FROM
  (127)
• (131) PPDM GEODETIC_TRANSFORM.COORD_SYSTEM_TO
  (100)
• (132) PPDM GEODETIC_TRANSFORM.DELTA_X UKOOA
  H1501 (dx)
• (133) PPDM GEODETIC_TRANSFORM.DELTA_Y UKOOA
  H1501 (dy)
• (134) PPDM GEODETIC_TRANSFORM.DELTA_Z UKOOA
  H1501 (dz)
• (135) PPDM GEODETIC_TRANSFORM.ROTATION_X UKOOA
  H1501 (rx)
• (136) PPDM GEODETIC_TRANSFORM.ROTATION_Y UKOOA
  H1501 (ry)
• (137) PPDM GEODETIC_TRANSFORM.ROTATION_Z UKOOA
  H1501 (rz)

9
Early Issues Topics

• Sub-types and Super-types
• Reference table usage
• Inconsistencies / Documentation
• Formats
• Units of Measure

10
Logical to Physical Model Projections
11
PPDM Sub-types and Super-types

• The Subtypes and Super-types should be reserved
  to the logical model design, and should not
  appear at the physical level.
• We found subtype variables represented in subtype
  tables
• The explanations on Super-types are sometimes
  confusing. The rules seem to be different in the
  different parts of the model.
• For example, COORDINATE_SYSTEM description
  mentions it is a Super-types. It should be green
  on the diagram (Spatial Geodetic).

12
Reference tables

• COORDINATE_SYSTEM_TYPE should refer to a
  reference table.
• Coordinate systems are always the same and can be
  in a reference table
• PRINCIPAL_MERIDIAN should be a reference table.
• This too should be a reference table with R_

13
Inconsistencies

• In the description of the table
  COORDINATE_SYSTEM,
• the Coordinate System (CS) types list is slightly
  different than in the description of the column
  COORDINATE_SYSTEM_TYPE
• Consistency (vertical CS instead of other
  CS).
• Color convention not respected in the coordinate
  system
•  SEIS_STREAMER has a unique ID, but not able to
  store a field survey ID.
• It is not recommended to use a business ID as a
  primary key.

14
Data Formats

• Different character string lengths
• UKOOA Line name 60 Characters 48 line prefix,
  12 for line name
• PPDM Line name 40 Characters
• Different number of significant digits
• Different digits yield precision loss
• Date and Coordinate Standards (UTM vs. Lat Long)
  requiring conversion algorithms
• Angles and dates can be expressed differently
  need an algorithm to equate

15
Handling Units of Measure

• Unit of measure should be set at the survey
  level.
• SEG/P1 and UKOOA files are setting this
  information in the header, not for the line or
  for the point.
• PPDM allows setting the unit of measure for depth
  or elevation at the point level (POINT.ELEV_UOM
  and POINT.DEPTH_UOM).
• It is very unlikely to have this unit of measure
  changed in the middle of a survey.
• At the survey level, setting the unit of measure
  for the survey is not so explicit.
• For elevation, DATUM_OUOM on COORDINATE_SYSTEM
  (referred by SEIS_SET.COORD_SYSTEM_ID) should be
  the reference.
• The same could be used for depth.

16
Summary

• By and Large the Mapping works, however
• SEG/P1 and UKOOA PPDM mapping has revealed some
  difficulties in using PPDM to build an efficient
  database.
• And someone else can build a database, but cant
  share
• These problems seem to be the result of
  successive minor improvements that didnt take
  the global schema into consideration.
• Documentation and limited recommendations
  encouraging
• Some compromises had to be found to complete the
  SEG/P1 mapping to PPDM.
• Need more documentation and recommendations

17
Next Steps and Questions

• Provide modifications to the PPDM model
• Review of the Seismic model
• Role of Standard Mapping recommendation
• Questions?

18
Idea/Suggestions

• Why don't UKOOA and PPDM association (as well as
  SEG1 and PPDM) don't work together to provide a
  standard mapping?
• If they all intend to provide standards, their
  mapping should be a standard too
• This standard mapping would reinforce the value
  of PPDM,
• Avoid every company to rewrite its own mapping
  which are always subject to personal
  interpretation.
• It would guarantee that PPDM is really used as
  intent by its authors.
• Data Exchange initiative is the way to go with
  its
• Will require some redesign in addition to the
• Documentation, training, import/export tools

19
Recommended information

• Positioning of Station Type in the model
• PPDM SEIS_LINE.SEIS_STATION_TYPE
• Resides in UKOOA item 1
• R_SEIS_STATION_TYPE.SHORT_NAME
• can also be specified at the point level, but it
  makes sense to have a consistent one for the
  whole line