Marine FWI of SEG/EAGE salt data

Multisource FWI with Frequency-selection on SEG/EAGE Salt Model




Figure 1. (Upper left) Actual velocity model. (Upper right) Initial velocity model.
(Lower left) Standard FWI after 69 iterations. (Lower right) Multisource FWI after 262 iterations.

Objective: Learn how to carry out FWI, specifically using multisource with frequency selection.

Procedure:

  1. Download the codes fwi_marine_Huang.tgz.
    Run: tar -xzf fwi_marine_Huang.tgz
    Then: cd code_SEG_EAGE_salt
  2. Assuming you have Intel Fortran compiler, compile all the code by running
    make
  3. Forward modeling, by running
    make runforw
    Verify that the CSG's have been generated, by
    ls csg2saltsub3_8
  4. Run standard FWI, by
    make runsing
    Verify that the velocity models have been generated per iteration, by
    ls fwiout2
    For example, the name
    salt_213x50_fwi_B60_69.dat means:
    The model is of size nx=213 (fast dimension) and nz=50.
    There are 60 supergathers ("B" stands for 'bundle', also known as 'supergather').
    Since there are 60 sources in total, this implies each supergather consists of a single source.
    '69' denotes the number of iterations spent to obtain this elocity model.
    grd_Salt_213x50_B60_69.dat is the counterpart for the gradient.
  5. Run multisource FWI, by
    make runmultb
    Verify that the velocity models have been generated per iteration, by
    ls fwiout2b
    For example, the name
    salt_213x50_fwi_B1_262.dat means on the other hand that:
    "B1" denotes there are 1 supergather, encompassing all sources.
    262 iterations are spent to obtain this elocity model.
  6. Use your favorite tool to plot out the velocity models salt_213x50_fwi_B60_69.dat and salt_213x50_fwi_B1_262.dat, which are on the lower row of Fig.1.
  7. The true and the initial velocity models can be found in the directory tomodat, named salt_velSub3_ny213_nz50_d90ft.dat and salt_velSub3Sm6_ny213_nz50_d90ft.dat, respectively. They are shown on the first row of Fig.1.