## SEPlib's library for building anisotropic models

SEP's anisotropic model building library was written by Dave Nichols 1989, and was recently made part of the standard SEP library, thanks in part to Joe Dellinger. The library can be downloaded from SEP's ftp site. A sample shell for creating the water-filled fracture model used in the text follows.

```503 himalaya> cat Frac.wet.csh
#!/bin/csh -f
if ( \$#argv == 0 ) then
echo  "SYNOPSIS: Frac.wet.csh excess%"
echo  "need percentage of cracking as argument"
exit(-1)
endif
set percent = \$1

echo "BOTTOM"
echo "unfractured, isotropic chalk"
create isochalk delz=1 rho=2.7 velp=5.0 vels=2.5

echo "TOP"
echo "TI shale cap-rock"
create tishale delz=1 rho=2.3  c11=29.81 c12=10.35 c13=10.35 c22=29.81 \
c21=10.35 c23=10.35 c31=10.35 c32=10.35 c33=20.7 c44=5.18 c55=5.18     \
c66=9.730

echo "FILLING"
echo "Water for filling cracks"
create water delz=1 rho=1.0  c11=2.25 c12=2.25 c13=2.25 c22=2.25       \
c21=2.25 c23=2.25 c31=2.25 c32=2.25 c33=2.25 c44=0 c55=0 c66=0

echo "Vertically cracking Chalk with \$percent EXCESS filled with water"
vcrack isochalk water chalk.\$percent.wet excess=\$percent

# make a two layer stack (using standard SEPlib, notice the ".H" now)
Merge tishale.H chalk.\$percent.wet.H axis=2 space=no > \$percent.wet.mdl
```

More information about the model library can be found in Nichols's 1989 report by invoking the online documentation of the library's programs.