SYNOPSIS
PERL PROGRAM NAME:
AUTHOR: Juan Lorenzo (Perl module only)
DATE:
DESCRIPTION:
Version:
USE
NOTES
Examples
SYNOPSIS
SEISMIC UNIX NOTES SUBACKUSH - calculate Thomsen anisotropy parameters from
well log (vp,vs,rho) data and optionally include
intrinsic VTI shale layers based on gramma ray log
via BACKUS averaging
subackush < vp_vs_rho.su >stdout [options]
subackush < vp_vs_rho_gr.su gr=1 >stdout [options]
Required parameters:
none
Optional parameter:
navg=101 number of depth samples in Backus avg window
Intrinsic anisotropy of shale layers can be included ...
gr=0 no gamma ray log input for shale
=1 input is vp_vs_rho_gr
grs=100 pure shale gamma ray value (API units)
grc=10 0hale gamma ray value (API units)
smode=1 include shale anis params prop to shale volume
=0 include shale anis for pure shale only
se=0.209 shale epsilon (Thomsen parameter)
sd=0.033 shale delta (Thomsen parameter)
sg=0.203 shale gamma (Thomsen parameter)
Notes:
1. Input are (vp,vs,rho) traces in metric units
2. Output are
tracl =(1,2,3,4,5,6)
quantity =(vp0,vs0,<rho>,epsilon,delta,gamma)
units =(m/s,m/s,kg/m^3,nd,nd,nd) nd=dimensionless
tracl =(7,8)
quantity =(Vsh,shaleEps) Vsh=shale volume fraction
units =(nd,nd)
3. (epsilon,delta,etc.) can be isolated by tracl header field
4. (vp0,vs0) are backus averaged vertical wavespeeds
5. <rho> is backus averaged density, etc.
Example:
las2su < logs.las nskip=34 nlog=4 > logs.su
suwind < logs.su key=tracl min=2 max=3 | suop op=s2vm > v.su
suwind < logs.su key=tracl min=4 max=4 | suop op=d2m > d.su
fcat v.su d.su > vp_vs_rho.su
subackus < vp_vs_rho.su > vp0_vs0_rho_eps_delta_gamma.su
In this example we start with a well las file containing
34 header lines and 4 log tracks (depth,p_son,s_son,den).
This is converted to su format by las2su. Then we pull off
the sonic logs and convert them to velocity in metric units.
Then the density log is pulled off and converted to metric.
All three metric curves are bundled into one su file which
is the input to subackus. ",
Related programs: subackus, sulprime
Credits:
UHouston: Chris Liner
I gratefully acknowledge Saudi Aramco for permission
to release this code developed while I worked for the
EXPEC-ARC research division.
References:
Anisotropy parameters: Thomsen, 2002, DISC Notes (SEG)
Backus Method: Berryman, Grechka, and Berge, 1997, SEP94
Shale params: Wang, 2002, Geophysics, p. 1427 User's notes (Juan Lorenzo) untested
CHANGES and their DATES
Import packages
instantiation of packages
Encapsulated hash of private variables
sub Step
collects switches and assembles bash instructions by adding the program name
sub note
collects switches and assembles bash instructions by adding the program name
sub clear
sub gr
sub grc
sub grs
sub key
sub navg
sub nskip
sub quantity
sub sd
sub se
sub sg
sub smode
sub tracl
sub units
sub get_max_index
max index = number of input variables -1