Calculate difference properties

fmu-pem is normally used for estimating 4D seismic response, and difference between simulator model time steps can be more important than absolute values. In fmu-sim2seis workflow, the difference is calculated from absolute values in a set of Vp, Vs and Rho parameters, ref. Save results. Additional difference parameters can be generated in fmu-pem for QC or calibration purposes.

A section in the YAML configuration file specifies which parameters are selected for difference calculation, and what kind of difference attributes should be estimated:

# For 4D parameters: settings for which difference parameters to calculate
diff_calculation:
  AI: [diffpercent, ratio]
  SI: [diffpercent, ratio]
  VPVS: [ratio]
  TWTPP: [diff]
  DENS: [diffpercent]
  VP: [diffpercent]
  VS: [diffpercent]
  SWAT: [diff]
  SGAS: [diff]

For convenience, it is possible to calculate differences of input parameter, as well, as in the example above for SWAT and SGAS. The three difference attributes that can be selected, are diff, diffpercent and ratio.

In the FMU directory structure, the difference estimates are stored in share/results/grids.