Dear all SGeMS users,
Here is a very confusing *problem *I met *with *SGeMS and *SISIM
categorial* (apparently inherent to SGeMS, never mentioned anywhere on
What I would like to do : a Sequential Indicator Simulation of
geological facies (categorial) conditionned upon synthetic data.
The inherent problem : realization of 3 facies instead of 2 as expected
(*always one more than expected in each case*).
First I simulated two random facies in Matlab (50 data points) in a grid
100 x 100, unit spacing. Then I run SISIM conditionned upon my hard data
in SGeMS to get one realization with 2 facies. In property item (Hard
data parameters) I selected facies data, not indicators (am I right?).
In interval data, I selected nothing. The problem comes when I select
'assign hard data to simulation grid' item. I get a realization with 3
facies instead of 2,i.e. one facies = 0, another one = 1 and the last
one = 2. The latter is restricted to the data point of facies 2. The
same problem also happens if I select my two indicators in interval data
and my facies in property. However, if I select one indicator in
property instead of facies, I get two facies as expected, but
conditionning occurs on one indicator only.
*I noticed the same problem in two examples*: one I found*in *a document
intitled : *"S-GeMS Tutorial Notes", 26 june 2007, Geoff Bohling from
Kansas Geological Survey*. Here, the author simulates 5 facies, but I
can see 6 facies in the realization (data and parameters are provided at
http://people.ku.edu/~gbohling/BoiseGeostat. Here is the document
http://people.ku.edu/~gbohling/BoiseGeostat/SGeMSTutorial.pdf. Also, *in
"Geostatistical Earth Modeling Software: User's Manual", Nicolas Remy ,
2004* : the example illustrated at Figure 3.8 using Stanford V data set
and the same parameters. Again, result seems similar but if we zoom on
it (in SGeMS), there are more facies than expected.
Any help would be greatly appreciated
Thanks in advance
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