dsw - Distance weighted grid

Name

dsw — Distance weighted grid

Syntax

Description

The dsw will create a distance weighted grid (dsw) which is an operator grid to be used in special grid operations. An application of the dsw grid is for use in well tieing to a surface.

A difference grid of distances of well points to the surface is first made and then multiplied with the dsw grid to control exactly how far out the updating influence will reach. The values of the dsw grid are between 0 and 1.

A standard grid is input to determine the layout of the dsw grid. The operator string define the shape of the dsw grid.

Algorithms: A smooth curve is interpolating the operator points. There are some curve interpolation options:

Interpolation options

• Spline is an interpolating curve through the input points.
• B-pline is an extrapolating curve using the input points as a guiding polygon.
• A usefull B-spline function is generated by the numbers: 1 1 0 0 .
• Tensor is using a fixed B-spline tensor values and will only vary with influence radius.
• Trim is used when it could be necessary to trim the dsw grid to get close to 1 on the tops under detailed control.

The result distance weighted grid will have values between 0 and 1 and is saved in workspace distanceGrid.

When the result grid is written back into the project, the name contains the algorithmic information for convenience.

The dsw command and its operation is handled in the command object Distance weighting in grid and is part of the Navigation module.

Arguments

hiname

Use well points in workspace hiname.

smo

The dsw grid will be smoothed and trimmed to have exactly values between 0 and 1.

The smooth option means an extra smooth step to secure that overlapping distance areas are smoothed out. If no influence area is overlapping another, the smoothing can be dropped if the operator numbers represent a smooth curve. When smoothing is applied no data point should lay on the border because it may disturb the smoothing.

exc excluding_steps

Number of smoothing steps using the grp exc excluding_steps smoothing algorithm.

trim

The dsw grid will be trimmed to have exactly values between 0 and 1.

dis distance

The distance of influence in the dsw grid; i.e the radius of the bell shaped surface. Default is 300.

ope "op1 op2 ..."

The operator string consists of operator values "op1 op2 ..." defining the shape of the sw grid. Be sure to include the operator string in between " ".

The operator string is usually a bell shaped curve going from 1 to 0. If not between 1 and 0, the normalize option will normalize the values between 1 and 0. Highest values shall be entered first.

The operator string can be saved as the y values of a curve, thus allowing for having several operator strings. The operator string will be spline generated, optionally having some tension between 0 (no tension) and 200 (close to linear).

nno

Not normalize the operator values to generate a curve from 0 to 1.

bsp

A b-spline curve is drawn from the operator points.

ten tension_value

A spline under tension curve is drawn from the operator points using tension_value.

res resolution

The resolution (number of points) in the operator curve. Default is 1000.

Examples

Ex.1: Generate a distance weighted grid

vie 2 1 1         ;# Set up 2x1 viewport and select 1
spe bgc whi       ;# Specify background color to white
win demo          ;# Get demo window (450000 460000 6450000 6460000 1000 4000)
mak ran 11        ;# Make random points
grp 333 333       ;# Make grid
mhi surface       ;# Move to surface
mak ran 8         ;# Make 12 randow points
ssc nog           ;# Scale and not update graphics
mhi welldata      ;# Save in welldata
mlo surface       ;# Move surface to active

# Calculate ditance weighted grid
dsw welldata dis 2000 bsp exc 8 operator "1.00 0.96 0.85 0.69 0.47 0.26 0.08 0.00"
ssc               ;# Scale grid
scaz 1000         ;# Scale z
map               ;# Map the dsw grid
vie 2 con         ;# Select viewport 2 and connect

# Calculate ditance weighted grid and use smoothing
dsw welldata dis 2000 bsp smo exc 8 operator "1.00 0.96 0.85 0.69 0.47 0.26 0.08 0.00"
map               ;# Map the dsw grid
xwi sel           ;# Force the window in front

The above example produces this image.

_Distanced weighted grid without smoothing (left) and smoothing (right) _

See also

bsp - B spline visualization, grp - Grid points and lines, spl - Spline generation