This is one of the initial commands to begin using the
block modeling
features of Carlson. It uses similar grid logic, for
location
and resolution. It will take a strata or bed and subdivide it into
vertical
divisions. This can be applied to stratafied deposits, or ore based
geology,
where it is not stratafied, such as limestone or copper, gold and
silver. In these
ore type cases, the strata or bed name could be just rock, or limestone
all the way
down the hole. It would then look at just the quality being modeled as
the
variable. The program takes this interval, makes a roof and a floor and
divides
it up equally into the number of vertical divisions specified, or at an
elevation "lift".
The first dialog brings up the Select Bed and Attribute
screen. One bed name must be selected, and one or more attributes
selected. If there are no Bed names in the drillholes, then select the
Model By Strata Names box to use just Strata names.
The next screen, Make Block Model, is for dimension and
modeling settings. The number of cells in the X and Y direction are
shown at the top. The total number of cells in plan view is shown next.
The average block height is calculated by the Number of Vertical
Divisions. There are two options to determine the Vertical Position.
The first one is by Fixed Elevations. This will activate the Bottom Z
and Top Z windows. Entering a roof and floor there, uses the Number of
Veritcal Divisions to calculate the vertical block size. Make
Block Model uses 3D Inverse Distance, 3D Kriging or Discrete as the
modeling method to produce the
block model of the quality values. The Prompt Each Attribute will allow
for different methods for different grades in the block modeling. For
example, Calcium can be modeled with Inversed Distance and Magnesium
modeled with Kriging. It will prompt for each before writing the BLK
file. The distance weight for the 3D
inverse
distance is the combination of the X-Y distance and the Z distance.
This
vertical factor is multiplied by the Z distance. So if there is no
special
correlation in the deposit for vertical, then the vertical factor
should be set
to 1. If there is some strata-like correlation based on deposit level,
then
this vertical factor should be set greater than 1, such as 10.
Discrete is a method to model parameters such as color. It will carry
one color 1/2 way over to the next drillhole, then switch to the other
color. This way, there is now blending of colors, if color1 is a 2 in
one drillhole and color2 is a 4 in the next drillhole, it will not
blend them to a "3" in the middle. It models 2, and then switches to 4
at the half way point.
After the routine is finished calculating, it creates a *.BLK file. This file can be viewed in a text editor to see what it contains, as shown here. Basically, it shows the roof and floor, the quality attribute name and the grid paths.
Pull-down Menu Location:
Block Model
Prerequisite: Drillholes with variable quality values that can be modeled.