Data modeling

Data were generated using SEPlib Kirmod3d program. The reflectivity map simply consists of a set of gradually dipping planes, from zero dip to $60^\circ$. The azimuth of the planes is $45^\circ$with respect to the direction of the acquisition, which maximizes problems in imaging.

 

planes Figure 7 Geometry of the set of slanted planes, dipping at $0^\circ$, $15^\circ$, $30^\circ$, $45^\circ$ and $60^\circ$ towards increasing x and y, at $45^\circ$ with respect to the in-line direction.

Data generated are on a regular grid and are common-azimuth, that is, with no cross-line offset component. The geometry of the grid is illustrated in Figure 8, with 64 samples in cmp-x and cmp-y, 128 in offset.

 

dim-grid
Figure 8 Geometry of the gridded synthetic data. The left represents a midpoint plane from the whole cube; the right is an offset plane. The common-azimuth cube has no cross-line offset, but can be zero-padded (light gray) in order to apply a 5-D phase-shift operator.

We used a very fine time sampling (1 ms) in order to minimize interpolation errors during modeling with Kirmod3d and sub-sampled data to 2ms afterwards. We generated Green functions with velocity law v(z)=1500+0.5z, which roughly corresponds to typical gradients found in the Gulf of Mexico.