The main controls on the modelled secondary migration and entrapment in MigriX are the layer geometries and entry pressure distribution. The entry pressure field affects the direction of migration and sealing capacity of traps. It is calculated from the permeabilities using the relationship shown in Figures 3.10 - 3.11. Entry pressure anomalies can be added using the Pe.add parameter.
The permeabilities are computed from a compaction function which takes the lithology fractions and burial depths as input. A scaling parameters for permeability (K.adjust) are also available to the user. Capillary pressure functions are used together with an hysteresis function in order to model capillary leakage from traps. The capillary functions are also combined with relative permeabilities in the flow calculations.
Figure 3.10 Permeability to entry pressure functions in MigriX.
Figure 3.11: Diagram after Ingram et al., 1997 displaying relations between Pe.k, Pe.P and Pe.slope and permeabilities parameters used to calculate entry pressures.
