Model ray-parameter gathers


Module overview

What will you learn in this module?

In this module you will learn how to model synthetic ray-parameter gathers using various data models in Helios.

What input data will be required in this module?
  • Well log data in .dil format
  • Optional: Ray-parameter range stored as .txt file
  • Optional: Wavelet(s) stored in .su format
What output will you have created in this module?
  • Synthetic ray-parameter gathers in .su format
  • Optional: Up-scaled well log data in .dil format

Instructions and screenshots

To model synthetic ray-parameter gathers in Helios three types of input data are required. Well logs data, a ray-parameter range for which the data is supposed to be generated and seismic wavelets. In the previous chapters of the documentation it has been described how each of these data types can be imported into the modelling module or how the respective data can be set by the user in the graphical user interface. Once the data types have been loaded, the user can further specify a number of modelling parameters. Each parameter has a default value so that even without further specification, the modelling process can be performed without further actions.

The basic parameters for modelling synthetic ray-parameters can be found on the bottom left of the interface. These include the following:

  • Depth axis: Can be either MD or TVD. If TVD is chosen, deviated wells will be projected back to vertical to allow modelling based on the 1.5-D data model.
  • Max. TWT [s]: Maximum two-way time to be modelled. By default this value is 0.2 seconds larger than the TWT of the last sample of the well logs. Increasing the maximum TWT allows modelling and visualising more of the coda which potentially is created by elastic modelling but not by linear modelling.
  • dt_mod [s]: Time sampling of synthetic gathers that will be created. This value is taken from the time sampling of the loaded wavelet and cannot be changed directly by the user. If a different time sampling is desired, a wavelet with a different dt needs to be loaded.

The remaining parameters fmax_mod and Field updates are only relevant when modelling synthetic wave-fields and are disabled as long as only synthetic gathers are supposed to be created.