MigriX utilizes a library of predefined lithologies to establish default properties for all user-configurable parameters. These primary lithologies can then be broken down into seven lithology fractions:
• Shale (Vsh)
• Low-permeable carbonate (Vca)
• Permeable carbonate (Vcp)
• Organic matter (Vom)
• Evaporites (Vev)
• Igneous (Vig)
• Sand (Vss)
The primary lithologies are mapped to the lithology fractions based on the scheme detailed in Table 3.4. Each layer must have a specified lithology More information about how to define the layer lithology properties can be found in the Lithologies section.
Table 3.4 MigriX lithologies
Lithology
Abbreviation
Vsh
Vca
Vcp
Vss
Salt
Salt
0
0
0
1.0
Shale
Shale
0.95
0
0
0.05
Silty shale
ShSlt
0.75
0
0
0.25
Silt
Slt
0.5
0
0
0.5
Silty sand
SltSS
0.25
0
0
0.75
Sandstone
SS
0.05
0
0
0.95
Low-calcaerous
sandstone
CaSs+
0.05
0.15
0.1
0.45
Calcaerous
sandstone
CaSs
0.05
0.3
0.2
0.45
Arenitic
carbonate
AreCa
0.05
0.45
0.3
0.2
carbonate
Carb
0.05
0.95
0
0
Argillaceous
carbonate
ArgCa
0.25
0.75
0
0
Shaly carbonate
ShCa
0.5
0.5
0
0
Calcaerous shale
CaSh
0.75
0.25
0
0
Mixed clastics
Mixed
0.34
0.33
0
0.33
The lithology fractions for each layer can be set as constants or grid inProperties/Input/Lithologies and viewed during simulations in Properties/Lithologies. Sand constitutes what is left after the other lithology fraction parameters are defined. In many cases only Vsh will be used. The other parameters all have default values of 0 for most lithologies. The lithology fractions for each sublayer is a combination of the strata model and the average layer fractions.
The Model/lithology plots will assist the user understanding the geological system being modelled. Lithologies are used as input to the lithology fractions for each layer (e.g. Vsh, Vca). Default values of Vsh, Vca, Vcp are defined for each lithology type. These default values are used for all layers where the lithology fractions have not been defined
