In MigriX a drainage area is defined as the area that encompasses lateral migration into a single trap. In order to view or export drainage areas, at least one time-step must be have seen simulated. After simulating, the drainage areas can be plotted for a single trap or a fill/spill sequence of traps for that time-step.
The first option for looking at drainage areas is found in the Results/Traps/Drainages command which will plot a colour-coded map of all drainage areas (Figure 4.3). The mapped value has been chosen to separate each drainage area visually for the user. The DrainageID property that will plot the ID of each drainage area.
Figure 4.3: Drainage areas(left) and flow-rate map (right) for a modelled carrier system.
A more detailed analysis of the drainage system can be obtained by picking a point within a drainage area in the 3D view and selecting PickDrainage in Results/Drainage in the Project workspace. This will result in a plot that shows only the local drainage area of that trap.
The LayerDrainage will plot the drainage areas of all the traps that can spill into the trap of the selected drainage area (Figure 4.4), while the DepthDrainage command will plot the depth map within the LayerDrainage area.
SpillDrainage adds the areas of the traps that the selected drainage area will spill into (Figure 4.5) and the NextDrainage will move the selection point to the next drainage area of the spill-path and plot the local drainage area of that trap. NextDrainage can be used recursively to move up along the spill-path and can be combined with the LocalDrainage, LayerDrainage and DepthDrainage commands.
Figure 4.4: PickDrainage shows local drainage area (left) while LayerDrainage includes all drainage areas within the layer that can contribute to the picked drainage area (right).
Figure 4.5: SpillDrainage shows all areas draining into trap plus the areas that the picked drainage spills into (left). NextDrainage plots the next local drainage area.
Drainage area analysis tool
The drainage area analysis window presents statistics for the picked drainage areas in table format. This includes the expelled oil and gas volumes, GOR, maturity, timing and average temperature for each source rock interval. In addition to the local and layer drainages computed by MigriX, it can also compute statistics within picked drainage area polygons.
Figure 4.6: Drainage area analysis window for the same areas as shown in Figure 4.4-4.5
Exporting drainage areas
A LayerDrainage area can be exported from MigriX as a grid or polygon file by selecting the layer, using the Save Property as Grid entry in the <RMB> menu and storing the gridfile in the file-selection box that will pop up. If a polygon file is wanted, simply use the Save Property Outline option. This file can be loaded back into Basemaps and used as a result overlay.
