CSIM Wave-equation Series Lab

By Xin Wang (xin.wang@kaust.edu.sa), Bldg 1, 3139-WS13, 808-0386

Part 1: TDFD solver to acoustic wave equation lab




CSIM Wave equation Series Lab

Part 1: TDFD solver to acoustic wave equation lab

PART 2: Reverse time migration lab

PART 3: Born modeling and adjoint test lab

PART 4: Wavepath lab;


Objective:

    Learn and run the time domain finite difference (TDFD) solver to the 2D acoustic wave equation.

Procedure:

  1. Define a 3 layer velocity model, and the model parameters;

    vel=[repmat(1000,[1,30]), repmat(1200,[1,30]), repmat(1500,[1,21])];
    vel=repmat(vel',[1 201]);
    [nz,nx]=size(vel); dx=5; x = (0:nx-1)*dx; z = (0:nz-1)*dx;

  2. Define the source and receiver geometry;

    sx = (nx-1)/2*dx; sz = 0;
    gx=(0:2:(nx-1))*dx; gz=zeros(size(gx));

  3. Setup FD parameters;

    nbc=40; nt=2001; dt=0.0005;isFS=false;
  4. Setup the source wavelet;

    freq=25; s=ricker(freq,dt);

  5. Plot the velocity and wavelet;

    figure(1);set(gcf,'position',[0 0 800 400]);subplot(221);imagesc(x,z,vel);colorbar;
    xlabel('X (m)'); ylabel('Z (m)'); title('velocity');
    figure(1);subplot(222);plot((0:numel(s)-1)*dt,s);
    xlabel('Time (s)'); ylabel('Amplitude');title('wavelet');
  6. Run the modeling code, watch the movie of wave propagation, and plot the seismic data;

    tic;seis=a2d_mod_abc28_snapshot(vel,nbc,dx,nt,dt,s,sx,sz,gx,gz,isFS);toc;

Reminder:

    For all labs, you can copy the bold line command to a single script, and run the scripts to generate the same results.

References:

  • Seismic Inversion, Gerard T. Schuster