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The size of the cube in z direction should be at least a little bit greater than the extent of the top and bottom surface. Also the x y extent should completely include the grid window. Then all the surfaces will fit into the velocity cube.
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All the time grids should be located in a folder which have the schema Layer Model. |
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It is also possible to convert just a single grid from time to depth using the velocity cube. Apply the commands for grids Grid operations->Depth conversion using velocity cube.
Example of depth conversion from time grid to depth grid.
The above picture shows an example of depth conversion a time grid into depth grid using a velocity cube and the same procedure as described above. All grids in the layer model were depth converted simultaneously.
Creating a RMS velocity cube and interval velocity cube
Having a stacking velocity cube, Geocap can do calculation on the cube and convert it into other cube types. It requires that the Navigation module is loaded (it will automatically if present). The dialog box below shows the menu after activating the CO Perform calculation on the velocity cube.
Dialog box for calculating RMS and Interval velocity cubes.
The RMS velocity cube is calculated according to the formula:
VRMSn = sqrt((Sum_i(Vi^2*Ti)/Sum_i(Ti)))
The Interval Velocity Cube is calculated according to Dix formula:
IVn Vn = sqrt((VRMSn^2*Tn - VRMSn-1^2*Tn-1)/(Tn-Tn-1))
These calculated cubes will help the professional to understand the geology of the subsurface based on velocity changes. The below picture displays the RMS and Interval velocity cube in the lower viewports.
Four velocity cubes displayed in a viewport presentation.
Upper left 'Raw velocity cube'. Upper right 'Smoothed grid updated cube'. Lower left 'Root mean square (RMS) cube'. Lower right 'Interval velocity cube'.
The above viewport presentation applies the viewport icon on the toolbar to make 2x2 connected viewports with different background color. Then each viewport is selected for displaying its appropriate cube. A cursor point is set within the cube using the keyboard letter p. Then the CO Cursor planes->Execute all command Cursor view>Map X Y Z pales at cursor position* is executed for each cube. The Tools menu Legend and text shell command tx2 lle col bla txt "text" was used for displaying a bottom text.