readme

su 的源代码库

README for RAYT2DAN          Debashish Sarkar   2003

This code depends on the CWP/SU (Seismic Unix) package,
available free from the Center for Wave Phenomena at:
www.cwp.mines.edu/cwpcodes

This code also depends on the proprietary code rayt2dan, available
to sponsors of the CWP Consortium. Contanct CWP for further information.

The program SURELANAN allows the user to determine coefficients
r1 and r2 that are necessary to describe residual moveout of migrated 
events in depth. r1 and r2 are substituted in the equation 

z(h)^2=z(0)^2+r1*h^2+r2*h^4/[h^2+z(0)^2] (Sarkar and Tsvankin, 2003),

to obtain estimates of the residual moveout.

Installation:

To install, edit the Makefile to reflect the needs of your system
and type:

make

Running the Demo:

This demo depends on the program  

rayt2dan 

This program must be installed before you can run this demo.

The demo shows an application of the code on one
overcorrected event at two CDP locations. To run the demo
execute the following shell scripts.

Susynlvfti  -- to generate test data
Rayt2dan    -- to generate traveltime tables for migration
Sukdmig2d   -- to migrate the data.

Surelanan   -- to begin the interactive demo for residual moveout
               picking


Start by picking 12 points (this number may be changed, 
if needed, in the script Surelanan) on the stacked image of  
one reflector. By doing so the reflector is delineated
and an estimate of z(0) is gleaned along the reflector. 
These picks are stored in file refl.1. At the selected CDP
locations pick the maxima on the two-parameter semblance
panels, which gives estimates of r1 and r2. 

These picks are
stored in the file cig.par along with the midpoint locations,
and may be used along with the code VELPERTAN to compute 
parameter updates

The file cig.par is the final output of this demo. This file
contains the coefficients that are necessary to describe the
residual moveout. This is example of the contents of cig.par
that you might see.  

cdp1=2000,-0.450038,-0.372307
cdp1=2500,-0.227943,-0.388967

The second and third values in each line correspond to the r1,r2 values
in the equation:

 z(h)*z(h) = z(0)*z(0) + r1*h^2 + r2*h^4/[h^2+z(0)^2] 

which is the non-hyperbolic moveout in depth for VTI anisotropic media.


Reference:
----------
Sarkar and Tsvankin, 2003, Analysis of image gathers in factorized VTI media:
Geophysics, 68, 2016-2025.