Welcome to this Session on SeisSIG - PowerPoint PPT Presentation

Title: Welcome to this Session on SeisSIG


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Welcome to this Session on Seis-SIG Standards on
seismic API data
An appraisal by ONGC
28th Nov 2007, Hotel Taj Lands End, Mumbai
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Why Seismic-Special Interest Group (Seis-SIG)

• Seismic and Well data are perhaps the most
  important assets of any EP company. They are
  very expensive to acquire and most often
  impossible to reacquire.
• Effective hydrocarbon exploration and production
  depends on using the new technologies to
  re-process and re-interpret available data  to
  extract maximum possible information.
• The test of a good interpretation is consistency
  with all the available data. At the very minimum,
  Managers should know enough about the data to
  judge the results.

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What is that Managers should know about data?
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Acquisition
Interpretation
Processing
Mumbai
SR, Chennai
GEOPIC
Under NELP, there are Multiple EP Operators
HampsonRussel
Paradigm
GF-Charisma
GF- IESX
SeisWorks
SeisWorks
Project D
Project C
Project C
Project E
Project B
Project D
Project G
Project H
Project A
Project F
Version 3
Version 1
Version 3
Version 2
Version 2
Version 1
Version 2
Version 1
Version 1
Confused?
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Data is generated, processed and interpreted by
different centers. Reprocessing/Reinterpretation
simultaneously by different agencies or at
different times creates many versions of data in
many different formats.

• The problem is further compounded by
• the way different Hardware Platforms storing
  characters
• (EBCDIC ASCII) and numbers (IBM IEEE)
  differently.
• b) and different Application Software modules
  storing data in
• their own proprietary formats.
• In addition, most of the legacy applications do
  not capture project metadata, and the onus is on
  the user to know what is what.
• Thus available data is in poor alignment with
  any of the standards

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IBM
IEEE
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Segy Floating Point Confusion
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• In this scenario, with tight schedules on hand,
  the business manager's most common gripe is that
  users are
• Spending too much time resources on getting
  data to
• different applications and platforms to
  function smoothly
• than on analyzing the data.
• But the business case demands solutions that
  integrate as easily and reliably as possible
  across business and science applications. Thus,
  standardization must play a key role.
• With application of standards, end users will be
  able to transparently connect the data that they
  need for their applications.
• Valuable time and resources that are spent on
  data manipulation tasks can now be utilized to
  analysis and decision making tasks.

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For accurate data storage and transfer among the
players the focus needs to be shifted from
application centric to data centric Practicing
standards is required to ensure availability of
correct data readily for the different GG
applications Organisations are now
understanding the importance and
significance of data and information about data
(meta data) and are forthcoming to support
their EP professionals.
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SEIS SIG
KEY SEED LIST AREAS for STANDARDISATION

• 2D, 3D 4D Acquisition
• 2D, 3D 4D Processing
• Results of Interactive Interpretation
• Generalized seismic data flow
• Unstructured data related to API activities
• Data compression and handling Voluminous 3D data
  over networks

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Positional uncertainties
While exchanging information about navigation
data, the map parameters for a specific geodetic
framework, are not properly documented. Based
on the conventions used in an area, the geodetic
parameters are assumed, hopefully correctly. God
only knows. Similarly, most of the deviation
surveys are marked as unknown north reference and
while loading it is assumed that it is grid
north. When the poor location data is used,
such an error will have an impact on the
property maps like sand thickness etc and can
also affect decisions with respect to new
well-locations. The next slide shows an example
of wrong map parameters. The black dots are the
sp locations with scale factor 1 while the red
ones are with a scale factor of 0.9996.
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• 2D, 3D 4D Acquisition Standards
• Uniformity in respect of
• Nomenclatures of Survey names, Line-names.
• Survey Summary Reports and Observers reports
  (unstructured)
• Equipment specifications
• Supply navigation P190 files (one per sail line
  vs combined for all sail lines)
• Supply of Gun Signatures (some times with
  Ghost, some times without)
• Storing of SP numbers (different byte locations,
  Integer vs BCD)
• Assigning Channel Sets (Trace channels and
  Auxiliary channels are changed in the same
  prospect for different sail lines)
• Providing bad trace information (given
  differently by different contractors)
• Logistics data (often not supplied)
• Tidal Information
• The List is end less

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Acquisition contd

• Problems faced in present SEGD seismic format
• Very short trace header (20 bytes)
• Bare minimum info is kept for navigation data
  checks
• Non availability of full Navigation information
  makes updating trace coordinate cumbersome and
• dependant on offline navigation data leading to
  geometry errors
• Timing word is the main link for navigation merge
• In case of errors, Field file number is the
  option. Non unique, descending order of field
  files complicate the navigation merging

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Acquisition contd

• SPS formats for acquisition geometry
• Three files (S,R and X) together need to be
  used to arrive at the geometry information
• X (relation) file alone contains field file
  number, whereas S (shot) file also requires for
  accounting mismatches
• Most of the times this file is not generated
  online during acquisition, but often generated
  after the data is acquired
• thus results in erroneous and inconsistent data
• A composite file of S,R and X needs to be
  thought of

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Processing related
Completeness of Observers Reports All the
necessary info. required for processing (Rec.
Instrument Parameters, Survey Geometry,
Feathering, Air Gun Behavior, Tidal Info. Gun
Signature, etc.) Seq. No/Swath no, FFID, SP,
Shot line necessary info, time stamp
etc. Anomalies in shot location and recording
info, tape problems etc. Raw data should also
include Navigation Data (UKOOA) Experience
shows all the related data for future processing
is getting misplaced and hence causing difficulty
in special processing at later stage.
The following few examples show Processing
problems in the absence of proper observer data
recorded during data acquisition.
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Stage-wise rectification of SPS errors
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SPS Problems
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Accounting of Recording delays
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Accounting of Improper Cable definition
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SEG Technical Standards Committee on Ancilliary
Data Formats
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Features envisaged in SEGD are Headers blocks
prior to seismic data to contain auxiliary
information about seismic data, acquisition
parameters, acquisition geometry, user
information External header to provide a means
of recording special user desired information.
This data format will be defined and documented
by the user. A trailer block (optional) is
recorded after all of the other data. This gives
additional time for collecting the data and
transferring it to the recording system. It can
have the accumulation of system faults, data QC
information, real-time navigation position, and
timing information on the same tape, and
contiguous with, the shotpoint that it relates
to. This needs that the navigation SPS database
is to be linked to the recording system for
accumulation of data. Equipment Manufacturers
and Acquisition Operators have to come forward
and address the issue.
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When it comes to acquisition format SEG-D, Rev
2.1 January, 2006 SEG standards booklet starts
as To begin with there was considerable
discussion as to whether a new revision of the
SEG-D standard is what is actually required, or
whether the time has come develop a completely
new format, SEG-E perhaps. Why? Because many
attributes were simply not envisaged when the
SEG-D format was first defined thirty years ago
and finding a place for them would require
significant structural changes to the format.
The diversity of views on what should be
included in the revision, boiled down to a
conflict between completeness and
compatibility. The major concern of shot and
receiver geometry for each shot, the position
information of receivers is addressed by
providing additional header blocks, external
headers and trailer blocks
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• Velocity formats
• VELF, Handvel, CGG, Promax, TDQ, GEOQUEST,.
• All are ASCII but the fields are different
• Most Interpretation S/W require strict adherence
  to their formats of velocities without any
  tolerance (any extra column is not acceptable)
• A universal ASCII format for velocity picks with
• inline, xline, x-cord, y-cord, time and velocity
  be acceptable
• (for 2D, Line name and SP instead of inline,
  xline)
• The header should contain type of Velocity (RMS,
  Stack, Migrated etc.)
• The velocities are to be adjusted relative to
  seismic datum.
• Application SW vendors to implement reading above
  format
• Interpolated Velocity volumes in SEGY need to be
  looked into