Tutorial: Create a P-Data Model and Isosurface Diagram

Estimated time: 4 minutes.

Now we will jump from the Striplogs menu, where we plotted observed data in log diagrams, to the P-Data menu, where the downhole quantitative data will be interpolated into a continuous model.

In this lesson, you will create a solid model and 3-dimensional isosurface diagram of the project's Gamma measurements. The program will load the recorded borehole data, that you viewed in logs and log sections already, and extrapolate the gamma values throughout the project. This modeling process basically "fills in the blanks" between the logs. RockWorks offers several modeling algorithm to do this extrapolation.

! You must be using RockWorks in Trial mode, or have a Standard or Advanced license to run this modeling program.

Before continuing, be sure you have opened the sample project, established the project dimensions and created 3D logs, as discussed in earlier lessons.

1. Back at the Borehole Manager, click on the P-Data menu and select the Model option.
    
2. Establish the modeling settings:
    Create New Model: Click in this button, and expand this item. This tells RockWorks that we want to interpolate a new solid model file.
   • P-Data Track: Click here to select from the pop-up list the column titled Gamma.  Expand this heading and be sure that none of the data filters are turned on.
   • Solid Model Name: Click here and type in:  gamma
     This will be the name assigned to the solid model to be created, with an ".RwMod" file name extension.
   • Solid Modeling Options: Click the Options button to access the various modeling settings.
     • Algorithms:  These options determine the method that will be used to interpolate the P-Data model.  Click in the IDW Anisotropic radio button to select this Inverse-Distance Anisotropic modeling method.
       
     • Additional Options - Turn the following items on/off. Note that you can click on any of these tabs to read more information.
       • Dimensions: These define the extents of the output model.
         • Based on Output Dimensions: Be sure this option is checked.
         • Confirm Model Dimensions item can be left unchecked (though in your own work, this is a handy way to double-check the model extents and node spacing).
       • Add Points: unchecked. 
       • Decluster: Checked. 
       • Cutoff - H, Cutoff - V: unchecked. 
       • Logarithmic: unchecked. 
       • Smoothing: Checked.
       • HiFi: unchecked.
       • Distance: unchecked.
       • Polygon: unchecked.
       • Superface: Check this to activate an upper surface (grid) filter, and click on the tab to access the settings. Choose Automatic.  RockWorks will automatically determine a surface representing the ground and filter out (nullify) nodes that sit above that surface.  Buffer Size: Set this to 0.
       • Subface: Check this option to activate a lower surface filter, and choose Automatic to filter nodes below the borehole bases. Buffer Size: Set this to 0.
       • Tilting: unchecked.  If activated, this can be used to apply a tilt to the model.
       • Warping: unchecked.  If activated, this can be used to warp a model based on a surface.
       • Faulted: unchecked.  If activated, you can use a 3D "fault file" to introduce faults into your model.
       • G=Color: unchecked. This is used for color modeling only.
       • Undefined:  Click here to select Null for undefined/filtered nodes.  In this case, nodes which lie above the ground surface or below the borehole bases will be set to the RockWare null value (-1e27); they will be invisible in display and will not contribute to volume computations, etc.
     • Click OK to close this window.
        
3. Create 3D Diagram:  Check this, and and click on the Options button (to the right) to access the diagram settings.
   • Diagram Type: Click on this tab and choose:
     • Isosurface: This will create a diagram in which the different G value levels can be represented as if enclosed within a "skin" that is like a 3-dimensional contour. Within RockPlot3D you will be able to interactively adjust the minimum P-data value to be enclosed within the isosurface contour.
   • Iso-Mesh: Uncheck this.
   • Plot Logs:  Check this.  The program will generate the 3D logs using the same settings we used in an earlier lesson in this section.
   • Cage:  Check this. Click on its tab to access the settings.
     • Dimensions: This should be set to the Automatic.
     • Panels: Be sure these are all unchecked. (Click the All Panels: Off button to disable all.)
     • Grids: These should also be unchecked.
     • Axis Labels: Check these options only; you can refer to the cartoon for a preview.
       • Southwest
       • Base / West
       • Base / South
   • Click OK to close the Block Diagram Options window.
   • Color Scheme: Click on this Options button to choose a color scheme that you like for the isosurface display. For example, for cold-to-hot gradational colors, choose the upper (2-Colors) option and click on the long color bar to choose the gradational scheme. Or, just click on the left and right color boxes below the long bar, to choose the colors which will represent the minimum and maximum values in the model.
   • Include Color Legend: Insert a check-mark here.
      
4. Click the Process button at the bottom of the P-Data Model window. RockWorks will create two items:
   
   It will interpolate a solid model at the specified project dimensions usng the Inverse-Distance Anisotropic modeling method. The model will stored in the project folder under the name "gamma.RwMod"
   
   Once the model is completed RockWorks will create an isosurface diagram to represent the model, with the full range of values displayed. The completed diagram will be displayed in a RockPlot3D tab.
     
5. View the isosurface model options by double-clicking on the Gamma item that’s listed in the data tree.  (You can also right-click on the Gamma item and choose Options.)

   

   The program will display a window listing the Isosurface Options. Here’s a quick summary:

   • Color scheme: Unlike the lithology model you may have created in an earlier tutorial, this solid model contains "G" values representing gamma measurements that range from a minimum to a maximum. The default scheme will be set to Continuous, to show gradations between the low and high values. .
   • Draw Style: Default is Solid. You might try changing the display to Wire Frame to see the effect. Click the Apply button at the bottom of the window to make any changes you set take effect. Using Wire Frame can speed rendering of the solid if it is dense or your computer system is slow.
   • Opacity: You’ll see this one in most 3D Options windows. You can make the block more transparent by reducing the percent opacity shown here. Again, use Apply to see changes take effect.
   • Cap Style: This tells the program how you want the "blobs" that intersect the edge of the model to be displayed. By changing the contour interval, you can see how the concentrations change inside the isosurface.
   • Iso-level: This allows you to see only selected G values in the block. See #8 below.
   • Slices: This allows you to see insert horizontal or vertical slices at specific locations in the block.

If you have a minute, you should go through the next few steps to learn some of the ins and outs of viewing isosurface diagrams. If you are in a hurry, you can review these lessons later in the dedicated RockPlot3D tutorial.

7. Adjust the View: Leave the Isosurface Options window open while you Rotate or Pan the image pane display. (You have full control over the image display even when one or more Options windows are open.) Or, use the View | Above, the View | Below, or the View | Compass Points tools to return to a pre-set view.
   
   You can save one or more views for quick access later, using the View | Add View option.
    
8. Change the iso-level being displayed: Click back in the Isosurface Options window, and find the slider bar in the Iso-Level section. The left-hand value on this slider corresponds to the minimum gamma readings, and the right-hand value represents the maximum.
   1. Drag the slider bar slowly to the right, with the intention of changing the minimum gamma level displayed, to see how the display changes. In your own work you can use the slider or just type a minimum desired value into the prompt.
      Remember, you can rotate and pan the image at any time without closing the Options window to get a better view.
   2. Set the Iso-Level to 50 by typing that value into the Iso-Level Value prompt and clicking the Apply button. The solid model representation will now display only those gamma values greater than or equal to 50.
       
9. Insert some slices:
   1. Now, click in the North-South button in the Slices section at the bottom of the Options window. This tells the program that you want to insert a vertical slice from south to north in the model. The slider bar will show the western project coordinate to the left and the eastern project coordinate to the right.
   2. Move the slider bar to the middle.
   3. Above the slider, click on the button on the left, and be sure that "Hide and..." is selected.
   4. Click the Add Slice button.
      The program will hide the isosurface and insert a north-south slice into the model, at the Easting coordinate shown above the slider, and it will insert a slice entity in the Data listing in the data pane.
   5. Drag the slider bar to the right and click Add Slice. The program will insert a slice along the eastern boundary of the model, and a new item will be listed in the Data pane.
   6. Repeat this process if you would like to insert vertical East-West slices. For these entities, the slider bar will represent southern coordinates to the left and northern coordinates to the right.
   7. If you want to remove a slice, right-click on the slice’s name in the data pane, and choose Delete from the pop-up menu.
   8. If you want to re-display the isosurface (blob), set the Draw Style to Solid.
       
10. Close the Isosurface Options window by clicking the Close button.
     
11. Adjust a slice:
    1. Double-click on one of the slices you had inserted into the model. You will see the Slice Options window.
    2. Locate the Position slider bar at the bottom of the Options window. Watch what happens as you drag the slider – the position of the slice in the view window will change as you drag the slider from left to right. The north-south or east-west coordinate (vertical slices) or elevation (horizontal slices) will be shown at the top of the tab as you drag. The slice’s coloration will vary as it moves through the solid model.
    3. Close the Slice Options window when you are ready to continue.
        
12. If you want to save this view, choose File | Save and enter:    gamma_solid     and click Save.
     
13. Close this RockPlot3D window by clicking in its upper-right Close box .
     

Solid Modeling Reference, Creating P-Data Models
 

  Back to P-Data menu     |     Next (interpolated cross section) 
 

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