NAME

     cdpstat  - module to aportion input source & receivers stat-
     ics  to output surface statics (applied before moveout), and
     output cdp statics (applied after stack).

SYNOPSIS

     cdpstat [ -Nntap ] [ -Ootap ] [ -srcsource ] [  -recreceiver
     ]  [ -cdpcdpvalue ] [ -surfsurface ] [ -nsnstr ] [ -nenetr ]
     [ -rsnrst ] [ -renred ] [ -V ] [ -? ]

DESCRIPTION

     CDPSTAT aportions input source & receiver statics between an
     output  surface static (applied before moveout), and an out-
     put cdp static (applied after stack). CDPSTAT requires  that
     the  source  &  receiver  statics  be  resident in the trace
     headers and that  the  data  be  sorted  into  CDP  records.
     CDPSTAT  computes  an  average  cdp-static as the sum of the
     total source and receiver statics  within  a  CDP.   CDPSTAT
     then  computes  the surface static as the total static minus
     the average CDP static.  Thus, the total static  equals  the
     sum  of the surface static PLUS the average CDP static.  The
     surface static improves moveout corrections by removing  the
     effects of surface elevation.  However, since the sum of all
     surface statics within a CDP is forced to zero, the  surface
     static  does  not alter the moveout correction measured from
     the surface.  The CDP static, on the other hand, is  applied
     after  stack  and  corrects the seismic data from a floating
     datum (achieved by  applying  the  surface  static)  to  the
     desired  datum.   The  two statics allow the user to improve
     moveout corrections with no deleterious effect on the  rela-
     tionship between velocity and the ground surface.

     The basic equations used to aportion the source  &  receiver
     statics are as follows:
     cdp_stat(j) = 1/N SUM {src_stat + rec_stat}.

     where the SUM is over all the source  and  receiver  statics
     within CDP j.

     And
     surf_stat(i) = total_stat(i) - cdp_stat(j)

     where the ith index refers to  the  individual  live  traces
     within CDP j.

     Since
     total_stat(i) = src_stat(i) + rec_stat(i) =  surf_stat(i)  +
     cdp_stat(j)

     then
     SUM {surf_stat} = 0 within CDP j.

     CDPSTAT gets both its data and its parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the start and end traces, mnemonics for  the  storage  loca-
     tions  of  input source & receiver statics as well as output
     cdp and surface statics, and verbose printout, if desired.

  Command line arguments
     -N ntap
          Enter the input data set name or file immediately after
          typing -N unless the input is from a pipe in which case
          the -N entry must be omitted.  This input  file  should
          include the complete path name if the file resides in a
          different directory.  Example -N/b/vsp/dummy tells  the
          program to look for file 'dummy' in directory '/b/vsp'.

     -O otap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  This output file is not required when
          piping the output to another process.  The output  data
          set also requires the full path name (see above).

     -src source
          Enter the mnemonic for  the  storage  location  in  the
          trace  header of the source static.  (Default = InStAp;
          formerly word 9).

     -rec receiver
          Enter the mnemonic for  the  storage  location  in  the
          trace  header  of  the  receiver  static.   (Default  =
          RcStAp; formerly word 12).

     -cdp cdpvalue
          Enter the mnemonic for  the  storage  location  in  the
          trace header of the output cdp static.  This value is a
          constatnt for all  traces  within  a  CDP.  (Default  =
          StaCor; formerly word 125).

     -surf surface
          Enter the mnemonic for  the  storage  location  in  the
          trace  header of the output surface static.  This value
          (allied  before  moveout)  follows  a  floating  datum.
          (Default=ToStAp; formerly word 13).

     -ns nstr
          Enter the start trace number.  The default is the first
          trace of the record.

     -ne netr
          Enter the end trace number. The  default  is  the  last
          trace of the record.


     -rs nrst
          Enter start record number.  Default value is the  first
          record.

     -re nred
          Enter end record number.  Default value is last record.

     -V   Enter the command line argument '-V' to get  additional
          printout.

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

BUGS

     ????????????

SEE ALSO

     rest(1) storeit(1) gli2disco(1)

AUTHOR

     Don Wagner

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.