2D Fluid Filled Borehole - Anisotropic Formation

This is a modelling guide to help you get started simulating Borehole Acoustic Measurement (Logging) systems in OnScale. In this initial example you will be shown how to get the dispersion plots using the symbol language

What is symbol?: Check out these articles to get more familiar with OnScale's scripting language symbol.

Note: This is not a MATLAB tutorial so there will be no instructions in this simulation guide on how to properly use the script. Upon download it will plot the dispersion spectra if all output data from the OnScale simulation is accounted for in the working directory

Model Description


The model we will show you how to build today will be a fluid-filled borehole surrounded by aformation. A formation is characterised as fast or slow depending on whether its shear wave velocity is slower or faster than the compressional wave velocity in the borehole fluid. These materials are assumed to be isotropic but in reality the formation material properties will be anisotropic so we have included an anisotropic definition of the formation.

Note: When you download this model it will origianally use anisotropic material properies for the formation. The project material file also comes with fast and slow formation material properties

Download and Open the Model

Download: Sonic Model 2D - Anisotropic

OnScale Input Files have the file extension *.flxinp. To open the downloaded file:

  1. Open OnScale 
  2. Select Analyst Mode
  3. Select the Menu button in the top left of the application
  4. Select Open

Preview Model


Preview model is used to view the geometry dimensions and material assignment of a model to ensure the script is correct. To preview a model, select the Preview Model icon in the Home tab of the application ribbon.


Note: Preview model will display data from any grph commands that come before the prcs command. If you have more than one grph command, you can cycle through the graphics by continuously selecting Preview Model. To close the preview, select Stop Preview.

Run Model on Cloud 

To run the model on the cloud, select the Run on Cloud button in the Home tab of the application and follow these steps:

  1. Click Select and open the file you wish to run (*.flxinp)
  2. Select Estimate
  3. Select Run
Note: Any supported files will be automatically included in the scheduler if they are in the same directory

Download Results

  1. From the Home tab, select the Storage icon
  2. Select the Refresh icon to refresh storage
  3. Select the Job Name from the dropdown menu
  4. Select the Download button
  5. Select Download All

Choose a directory to download the results to. These results will be stored in the folder: *-YYYYMMDD-HHMMSS\1 where YYYYMMDD-HHMMSS is the current date and time.

Analyse Results

We post-processed all of our results in MATLAB, we can provide a MATLAB script that we used. This is not a MATLAB tutorial however so there will be no instructions from here on out but here is a what the processed results look like if the script is used correctly. These results are from the anistropic formation  simulations. Included in the files provided is a folder 'utils' this should be added to the MATLAB path

Note: For post-processing the waveforms for the dispersions plots we used the “SFK waveform transform” toolbox. This was NOT created by OnScale and it can be obtained from the MATHWORKs webpage. It is not optimal and we would recommend using a better dispersion algorithim.


What's Next?

Simulate a full 3D Fluid Filled Borehole

Get more familiar with OnScale's 3 Modes and their capabilities