61
the samples within the domain D. The accumulation of a grade variable is calculated along
each drillhole as a new variable in a point file. The accumulation is the result of the following
Equation 1:
accumulation
V L
i
n
i i
V L
V
=
=
∑
1
(1)
where Vi is the grade variable to compute the accumulation; and Li is the analyzed length of
a drillhole which is the sum of the length of the selected samples for which the grade variable
is defined (Bleines 2012).
With the variographic modelling of the gaussian variables, and a search neighborhood
“SN”, the next step consists in performing the conditional co-simulation of the variables
acc_v1 (gaussian) and thickness (gaussian) on a 50 × 50 m grid (Figure 2). The total amount
of realizations is 100.
2.4 Create virtual drillholes from the simulations
With the results of the simulations, five scenarios were selected among the set of realizations
of each variable (acc_v1 and thickness), to create five possible realities that will be the basis
for the study from this stage onwards.
Such selection was done with an Isatis
® tool named “Simulation Reduction” that was
developed by a joint consortium of Geovariances and the CERNA (Centre of industrial economics of MINES ParisTech) which created an efficient method for selecting the best subset
of a predetermined size, k, from an original set of N simulations. The k simulations selected
are no longer equiprobable: some simulations represent “typical” deposits that are likely to
occur; other ones are less likely and some other ones are outliers (Armstrong et al. 2013).
Due to the co-simulation of acc_v1 and thickness v2, the same five scenarios were chosen
for both simulations among the set of realizations. The results obtained with the respective
probabilities for each scenario are listed in the Table 1, presented below:
Finally, from the previous stage, the virtual drillholes were defined, from the five realizations of the grade v1 and the thickness v2, by resampling each selected realizations with a
Figure 1. Map of the dataset.
the samples within the domain D. The accumulation of a grade variable is calculated along
each drillhole as a new variable in a point file. The accumulation is the result of the following
Equation 1:
accumulation
V L
i
n
i i
V L
V
=
=
∑
1
(1)
where Vi is the grade variable to compute the accumulation; and Li is the analyzed length of
a drillhole which is the sum of the length of the selected samples for which the grade variable
is defined (Bleines 2012).
With the variographic modelling of the gaussian variables, and a search neighborhood
“SN”, the next step consists in performing the conditional co-simulation of the variables
acc_v1 (gaussian) and thickness (gaussian) on a 50 × 50 m grid (Figure 2). The total amount
of realizations is 100.
2.4 Create virtual drillholes from the simulations
With the results of the simulations, five scenarios were selected among the set of realizations
of each variable (acc_v1 and thickness), to create five possible realities that will be the basis
for the study from this stage onwards.
Such selection was done with an Isatis
® tool named “Simulation Reduction” that was
developed by a joint consortium of Geovariances and the CERNA (Centre of industrial economics of MINES ParisTech) which created an efficient method for selecting the best subset
of a predetermined size, k, from an original set of N simulations. The k simulations selected
are no longer equiprobable: some simulations represent “typical” deposits that are likely to
occur; other ones are less likely and some other ones are outliers (Armstrong et al. 2013).
Due to the co-simulation of acc_v1 and thickness v2, the same five scenarios were chosen
for both simulations among the set of realizations. The results obtained with the respective
probabilities for each scenario are listed in the Table 1, presented below:
Finally, from the previous stage, the virtual drillholes were defined, from the five realizations of the grade v1 and the thickness v2, by resampling each selected realizations with a
Figure 1. Map of the dataset.