NAME
slvr - build 2D and 3D velocity data sets under horizon
control
SYNOPSIS
slvr [ -vvtap ] [ -Ootap ] [ -Phtap ] [ -sinsi ] [ -eiend ]
[ -tdfn ] [ -geco ] [ -digi ] [ -xsd ] [ -lmk ] [ -D3 ] [ [
-liminlimin ] [ -limaxlimax ] [ -dimindimin ] [ -dimaxdimax
] [ -x1ix1 ] [ -y1iy1 ] [ -x2ix2 ] [ -y2iy2 ] [ -x3ix3 ] [
-y3iy3 ] [ -x4ix4 ] [ -y4iy4 ] [ -cldmdx ] [ -ildmdy ] [
-tolrad ] [ -f2m ] [ -m2f ] ] [ -debug ] [ -V ] [ -? ]
DESCRIPTION
slvr is an attempt to resurrect some of the functionality of
the old SIS program of the same name. It is supposed to
take input velocity functions of several types of format and
under horizon control interpolate an output velocity data
set in either 2D or 3D. Some of the input command line argu-
ments are similar to vi3d.
The basic kernel of this program is how the interpolation is
done between non-flat horizons. The input functions are
first interpolated in time to be velocity traces keyed to
locations. Then at any output location the neighborhood
functions are identified and the times at which the horizons
intersect the control velocity traces are extracted. Between
any two horizons (including the surface and the last sample)
the minimum time at a control point is identified. The velo-
city interval between the two horizons at any other contri-
buting control trace is then re-gridded to have the same
number of samples as the minimum interval. Interpolation
onto the output location interval using the control traces
can then be done in a standard manner after which the inter-
val on the output trace is gridded back to the proper number
of samples. The process moves down dropping the current top
horizon and picking up a new bottom horizon until the output
velocity trace has been completed. Then the next output
location is chosen.
slvr gets both its data and its parameters from command line
arguments. These arguments specify the input, output, the
trace length, the sample interval, and a number of options
for 3D, and verbose printout, if desired.
Command line arguments
-v vtap
Enter the input ascii velocity data set name or file
immediately after typing -v. Only certain formats are
supported (TDFN for 2D and three format styles for 3D).
Use progam vomit to convert from some other format to a
supported one. This input cannot be piped.
-P htap
Enter the input horizon data set name or file immedi-
ately after typing -P. This file is always xsd format
for 2D and Landmark style format for 3D. Certain res-
trictions apply: each horizon must span the data set;
horizons must be input from shallowest to deepest; hor-
izons may not intersect. This data set cannot be
piped.
-O otap
Enter the output velocity data set name or file immedi-
ately after typing -O. This is always a USP data set
and can be piped.
-si nsi
Enter the sample interval (ms) for the output velocity
data set. In 2D the default value will be extracted
from the first line of the xsd horizon file. In 3D this
value must be supplied on the command line i.e. no
default.
-e iend
Enter the end time of the output trace (ms). No
default.
-dimin dimin
Enter the minimum DI (in 3D) or CDP (in 2D) number to
output. This (and dimax below) will govern the number
of output traces in this direction. In the 3D case this
will extract a subset of the whole cube defined by the
XY corners and the cell dimensions below). Default = 1
-dimax dimax
Enter the maximum DI (in 3D) or CDP (in 2D) number to
output. This (and dimin above) will govern the number
of output traces in this direction. In the 3D case this
will extract a subset of the whole cube defined by the
XY corners and the cell dimensions below). Default: for
2D the xsd pick file header is used to compute dimax;
default: for 3D the DI dimension defined by XY corners
for 3D
-limin limin
For 3D option: enter the minimum LI in 3D number to
output (not used for 2D). This (and limax below) will
limit the number of output traces of the volume in this
direction to a subset of the whole cube defined by the
XY corners and the cell dimensions below). Default = 1
-limax limax
For 3D option: enter the maximum LI in 3D number to
output (not used for 2D). This (and limin above) will
limit the number of output traces of the volume in this
direction to a subset of the whole cube defined by the
XY corners and the cell dimensions below). Default =
max dimension defined by XYs
x4, y4]
-x1, -y1, -x2, -y2, -x3, -y3, -x4, -
y4 [x1, y1, x2, y2, x3, y3,
For 3D option: enter the area of interest over the sur-
vey with the X-Y coordinates (ft,m) defining the four
corners of a parallelogram on the ground. Going either
clockwise or counter clockwise from Corner 1 the first
move to Corner 2 should be in the direction of a
receiver or shot line. The direction 1-2 will always
define the Y or DI direction. The DIs will always start
from side 1-4 and increase in the 1-2 (Y) direction;
the LIs will always start from side 1-2 and increase in
the 1-4 (X) direction. The values must be the same
units as those given in the source, receiver, and mid-
point X-Ys in the trace headers.
-cldm cldm
For 3D option: enter the crossline (along X or side 2-
3) cell dimension (ft,m). For most shooting geometries
this will be 1/2 the line or group spacing depending on
the orientation of side 2-3 with respect to the
receiver lines. The sides are defined to be X along
side 1-4 (roughly cross-line direction), Y along side
1-2 (roughly in-line direction). Remember when setting
up the coordinate system the line joining Corner (1) to
Corner (2) should be in the direction of a receiver or
shot line. No default.
-ildm ildm
For 3D option: enter the inline (along Y or side 1-2)
cell dimension (ft,m). For most recording geometries
this will be 1/2 the line or group spacing depending on
the orientation of side 1-2 with respect to the
receiver lines. The sides are defined to be X along
side 1-4 (roughly cross-line direction), Y along side
1-2 (roughly in-line direction). Remember when setting
up the coordinate system the line joining Corner (1) to
Corner (2) should be in the direction of a receiver or
shot line. No default.
-tol rad
For 3D option: enter the search radius (ft,m) used to
find functions in the neighborhood of any given output
location. The larger this value the smoother the
resulting volume. A cosine tapered weight as a func-
tion of radius is applied the the contributing neigh-
borhood functions so that more distant functions
contribute less to the interpolated values than nearer
ones. Default is 10 times the given cell dimension.
-tdfn
Enter the command line argument '-tdfn' to specify the
input velocity functions as tdfn. There is no other
option for 2D (use vomit to convert from some other
format). For 3D this will be the VDS 3D format.
-geco
For 3D: enter the command line argument '-geco' to
specify the input velocity functions as geco-style for-
mat. Each function will have two header lines the
second one specifying the XY location of the function.
The following lines will be time velocity pairs each
entry prefaced respectively by a "t" and a "v"
-digi
For 3D: enter the command line argument '-digi' to
specify the input velocity functions as digicon-style
format. The file will consist of a line for each time
velocity pair: column 1 is the LI number; column2 is
the DI number; column 3 and 4 are the X and Y location
of the function; column 5 and 6 are the time and velo-
city.
-D3 Enter the command line argument '-D3' to specify the
output is to be a 3D velocity volume; otherwise a 2D
operation will be assumed.
-xsd Enter the command line argument '-xsd' to specify the
horizons are xsd pick segments (2D case only). Each
segment must go all the way across the line and the
segments must be picked from shallowest to deepest.
-lmk Enter the command line argument '-lmk' to specify the
horizons are landmark style horizon files (3D case
only). All horizons must be in this file and must be
separated from each other by a null or blank line. Each
horizon will be extrapolated to the edges of the user
defined survey and will be filled in so that every cell
will have a time. Horizons must be ordered in the file
going from shallowest to deepest.
-f2m -m2f
For 3D option: enter the command line argument '-f2m'
or '-m2f' to change horizon XYs from feet to meters or
meters to feet. Default is to change nothing.
-debug
Enter the command line argument '-debug' to dump the LI
DI and times of all horizons into a file called
'SLVR_HORIZONS'. This file can then be plotted using
|fBplotxy.
-V Enter the command line argument '-V' to get printout of
all the horizon times. For 3D this could be a lot of
information.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
BUGS
All horizons must entirely traverse the data set and must
not cross. There are currently no checks to make sure these
conditions are set.
EXAMPLES
1. 2D
slvr -v vel_func -P horzs -dimin 1 -dimax 1660 -e 5996 \
-O vel_data
where the default TDFN velocity functions are contained in
file vel_func, the xsd horizon picks are contained in file
horzs (the sample interval in the pick file is 4 ms), and
where the output vel_data is a usp velocity data set con-
taining 1660 traces, each with 1500 samples.
2. 3D
slvr -v tdfn_crds -O vel_vol -tdfn -P bigdon D3 \
-e 5996 -si 4 -tol 1000 -limin 1 -limax 76 \
-dimin 1 -dimax 76 -ildm 200 -ildm 200
where tdfn_crds contains the velocity function in VDS TDFN
format, the horizon files are in bigdon (in landmark-type
format), and where vel_vol is the usp format output velocity
volume. The search radius is set to 1000 (which is 5 cells
since the cell dimension is 200).
SEE ALSO
vi3d, vomit, velin
AUTHOR
Paul Gutowski, EPTG, pgutowski@amoco.com
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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