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C.S.E. G. Geophysical Workstation SEGY Standards

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C.S.E. G. Geophysical Workstation SEGY Standards Powered By Docstoc
					        SEP-19-2002 13:11                                      LTD.
                                                    GEO-XSYSTEMS                                               403 264 1057              P.02/03

    C.S.E.G. Geophysical Workstation SEGY Standards
 by DougBath                                         that il was far beyond our mandate to sug-     dards outlined will be folIowcd for 'lJ1 new
                                                    gest a replacement for the SEGY format.         SEGY data. but t:hiscan only happen if the
    Following  is a list of the SEGY                We also recognize tbat the thousands of         consumersof this dara (i.e.. (he oil compa-
StandardsCommittee:                                 SEGY tapes now in existence will probably       nies) ask that their vendors adhc:re to the
                                                    not be updated to the CSEG standard It is       CSEGSEGYstandard.
    Bruce Gawalko SceplIe. ResoWt:es
                                                    [he bope of [his committee that [he stan-
                           Lid.
      LaITYAdorjan       Amoco C.1nada  Ltd.        SUGGESTED
      Larry Wallon       Veritas Seismic Ltd.       STANDARDS FOR SEGY TAPES
      John Vermene       Dyad Daro Services         2D and 3D data
                           Ltd                      ]) 3200 byte EBCDIC headerconsisting of:
     George Wirth        Dyad DataServices              Area name:
                          Ltd.       .
                                                        ProcessingCenter:
     Tom Cox             GeoQuestSystems                Processingdate;
                          L.td.                         Datum elevationus~d for StruchlfeStatics;
     Ron Smaniono        Vector Archives Ltd.           Time to rust sample:
     Ken Hedlin          Husky Oil                      Processinghistory asdeWled aspossible;
                          OperationsLId.                Survey datum(NAD27. NAD 83):
                                                        UTM Zone or central meridian;
     Dwight              Landmark!                      Headerbyte locAtions for critical items such as shorpoint. X Y coordinatcs.
      Mjldenberger        ITA Ltd.
                                                    2) 400 byte binary headercontaining at least:
     Dave Morgan         Geo-X SystemsLtd.
                                                       Byte Location            Formal               Value                        .~
     Allan Willis  Geo-X SystemsLtd.
                                                       17-18                    16 bit integer       Sample rareofrhis data in microseconds
     Danol Proskow Boyd Exploration
                                                       21-22                    16 bit integer       Number of samples tor this data
                          Lcd.
                                                       25-26                    16 bit integer       Data Sample forIIlat code
     Dave Coldham        Kernel Technology                                                           1      32 bit floating point
                          Ltd.                                                                       2      32 bit integer
     Jolm Townsley  Geophysical                                                                      3      16 bit integer
                      MiCrtM;omputer                                                                 4      32 bit integer with gain code
                      Applications Lcd.                                                              5      36 bit floating point
     David Jenkins   Kerr McGee                                                                      6      IEEE 32 bit floating point
      (Co-Chainllan) CanadaLcd.                                   .8                                        8 bit integeI"
     Doug Bath      rrs Interactive                    55-56      '.            16 bit integer       Measurementsystem
      (Co-Chairman) Technical Services                                                               1 metres
                          Ltd.                                                                       2 feet
    With the proliferation of geophysical              399-400                  16 bit integer       Timc to fust sample in ms,;..
                                                                                                                                           'c"'-   c
workstAltions in thc industry it was felt by        3) 240 bytc trace header
several members that th~ standards for
SEGY stack data should be re-examined               4) Sample values written in foJ;mat  indicated in (2) above. Record length and sample rate
and if necessary brought up-to-date.                   fIXed for eachline. Inrer.record g~ betweenta~ block..;(Tape media only). One lrace
Accordingly a committee wa,q     folTned to ills-      per block.
CU5$    sr;mdards for geophysical workstation
SEGY data fomlats. The following is a sum-          S) EOF.
mary of ~ committee's recommendations.                   Each line written (0 tape should follow the above sequence with onl: EOF betWeen
This committee actually followed in the             lines and 2 EOFS after the la.~tline. Subsequenttapes in multi-tape volumes should I1nve
footsteps of a previous committee fomled in         EBCDIC :md binary headersat the start of eachtape.
 1987 to examine the same issue. Their find-
ings can be found in the October 1989issue          SUGGESTED STANDARDS
of me Recorder. While their recommenda-             FOR SEGY TRACE HEADERS
tions are still valid roday, (in fact they form
the backbonc= this committee's report), it
                 of                                      The following should be the minimwn infomlntion in each trace headerfor ZD stack
is evident to anyone involved in workstatil)n       d:l.m:
d,,(.'\ londing that the standards rcCOm-              ~l'!elocation!:.?~~t                          V~J!:e_-
mended are not being rigorously adhered10.             [.4                      32 bit integer       Trace number within       line
Although the limitations of the SEGY for-              5-8                      32 bit integer       Trace number within       volume
 m:1t. arc well known. and are being                   17-20                    32 bit integer       Interpolated station       numbc:r :lbove this
addressedby the Perroleum Open SI3nd:1rds
                                                                                                       CDP multiplied by       1000
Con)ortium (P.G.S.C.). this committee felt.
                                                       21-:2.1.                 32 bit integer       COP number

                                                                                                                 p.n,,- i994    ~KG    Rooonier        g
         SEP-19-200213:12                              GEO-X SYSTEMS LTD.
     ~~"elocation                  Format                 value                                                        403 264 1057            P.03/03
     19-JO                         16 bit intcger        Trace ID code                                    12)Line range (May b~ referrcd 10 as
                                                         I        Live trace                                  collJmns.inlines. nonh-south line\;, etc.)
                                                         2        dead trace                              13) Trace range within line (MOlY be
     71-71                         J6 bil integer        Coonlin3te scalar.Positive for n)ultiplitr.
                                                                                                              refcrred to as rows, crosslines. east-west
                                                 negative for divisor
     73-76                        32 bit integer  X coordinateof CDP                                          lines. etc.)
     77.80                        32 bit inreger Y coordinateof CDP                                                                    set
                                                                                                          )4) Oricntation of rhjs dOlta (north-south
     g 1.84                       32 bit integer X coordinateof CDP                                           or east-west)
     85-88                        32 bit integer Y coordinate of CDP                                     15) Azimuth anglc: of this data set (Use a[
     89-90                        16 bil integer Coordinareunits
                                                                                                           .least 5 decimal place$)
                                                 1 Length. Men-esor feet (UTM)
                                                                                                         ] 6) Bin size in barb directions
                                                           of
                                                 2 SeI:OOds arc (Lat-long)
     115-116                 16 bir integer      Numi-=rof samplesin trace                               ]7) X Y coordinates for all CoW'  corners
     ] J7-118                16 bjt integer
                                        ,
                                                 Sample interval in microseconds
                                                      -                                                  18)Tape numb.erin multi-tape sequence
* All traces, evcQzero fold dead tracesshould be annotared-                                              ) 9) Indicate if dead traces dropptd.

                                                                                                              The fallowing items are desirable but
                                                        trace headerfor 3D stackdata:
The following should be me lninirnum information in e.ach
                                                                                                         not essential.Applies to 20 and 3D labels:
    Byte'
    -,
                                  Format                 Value
                                                                                                         1) Header byt~ locations for criti~al items
     17-20                       32 bit integer         Row Dumber (Crossline. east-west
                                                                                                            such as shctpoint. X Y coordinates, row
                                                        line. erc.)
    21-24                         32 bit integer        Column number (inline. north-south                  column
                                                        line. etc.)                                      2) Survcy datum (NAD 27. NAD 83)
    29.30                         16 bit integer        Tm~ ID code                                      3) UTM Zone or central meridian
                                                         1      Live UDce                                4) Timeto first sample.
                                                        2       deadttace
    71.72                         16 bit integer        Coordinatescalar.Positive for multiplier,
                                                                                                              If SEGY volumes consist of multiple
                                                          negaIivefor divisor
    73-76                        32 bit integer         X coordinateof bin centre'                       ve~ioDs of lines me version of ilie line that
    77-80                        32 bit integer         Y coordinareof bin centre.                       is moSt likely [0 be loaded onto a worksta-
    81-84                        32 bit integer         X coordinateof bin cenQ'e                        tion (e.g., filtered migration) should be the
    85-&8                        32 bit integer         Y eoordinateof bin centre                        fust file on tape followed by the other ver-
    89-90                        16 bit integer         Coordinal:e  wlits                               sions in descending order of loading proba-
                                                        11eng1h.  Metres or feet (UTM)                   bility (e.g., filtered sirue(Ure stack. unfil-
                                                                    of
                                                        2 Seconds an: (Lat. long)
                                                                                                         tered migration. unfiltered structure). With
    115-116                       16 bit integer        Nwnber of samples in trace
                                                                                                         multiple lines all d'le lines of each process-
    !..!!.11~.        .--16             bit integer.          intervalin microseconds
                                                         Sample
                                                                                                         ing type should be grouped togeilier to facil-
                                                                                                         itate dala loading (i.e-. all the filtered migra-
                                                                                                         tions followed by all the filrered structures,
     The outside .label of a SEGY tape can             11) Shatptlint range (From fIrSt (race to ]ast,   etc.).
be an imponant source of infonnation about                 not just field shot I1IDge).                  The aim of thc committee was lo pub-
the tape or extremely vague and misleading.                                                        lish a rcasonable standard that couJ,dbe
                                                       12)Trace number within line , ';, '!~':c
                                                       13) Sbo~int scalar (1000)         ,.. c .
The following .~t~ndards are offered as a                                                          ~dhered to by all panics without making
guide to the minimum information that                  14)Tape number in multi-tape sequence.      major $oftware changes- Accordingly wc
should be found on a tape label.
                                                             The following should be the minimum have avoided changes to the existing stan-
     The following should be the minimum               infonnarion on the outside label of a 3D dard. The only item if! the above standard
information on the outside label of a 2D               stack. tape:                                that is n~Wis the additional option for the
stack tape:                                              1) Area name                              flag in the binary header to denote IEEE
  ] ) Area name                                          2) Companyname                            floating point. Most if not all seismic pro-
  2) Company name                                        3) Prospect name (If different from area cessingand rape copy centres are capable of
  3) Line name(s)                                           name)                                  writing SEGY data (0 this ~tandardnow. It
  4) Processor                                           4) Processor                              is up to the indU5tty [0 encouragethcm (0 do
  5) Pr(lce~5ingdatc                                     5) plt)Cessing date                       so.
  6) Type of processing (At leasl stack or               6) Type of processing (At 1eastsrack or         The committcc wishes to [hank the
      prc-stSck. as extensive as spacepemrlts)                         as
                                                            preAStack.. ex[ensiveas space permits)
                                                                                                   C.S.E.G. Execulivc for encouraging (Jur
  1) Tape den~jt}. (lmponant for 8 mm tapes              7) T~ dcnsi[y ampon.:mtfor 8 mm tapes
                                                                                                    work and also ,gjve~tlIanks (0 !.hemembers
      as well as 9 track)                                   as well as 9 b'ack)
                                                                                                    of the previous committee for their efforts.
  8) Record length in ms                                 8) Record length in ms
                                                         9) Samplera[e in rns                      We thank all the people in rJ1e industI), who
  9) Sample rl1lt in ms
                                                        10) Fonnat (Floating point Integer)        offered their views and advice.
 10) Format (Floating point. Integer)

10 csaa Ae~ant8r       jill/t,   J994

				
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