Facies modeling and petrophysical modeling (Figure 1) will be detailed in chapter 2, which focuses on geostatistics.

Geostatistics allow to create multiple possible spatial distributions of the facies (and the petrophysics). Each respects the input data. It’s an efficient way to study the uncertainty associated to rock properties distributions. Figure 2 gives an example of two such spatial distributions given facies data at well locations and some information about the global facies proportions and the general orientation of the facies geobodies.