2D modeling and basic processing with Madagascar

Compute RMS Velocities, NMO, T-shift, Amplitude Correction, Stack

The basic trace processing stages of sorting to CMP gathers, time shifting, amplitude correction, normal move out, and stack are applied using the trace and header (tah) programs. These programs all start with ‘sftah’. The sftahheadermath program was used to load the geometry into the trace headers. The sftahnmo program requires an RMS velocity in m/s at each input CMP and each time sample. This is computed from the original interval velocity model by stretching to time, squaring the velocity, integrating, dividing by time, and taking the square root using the programs sfdepth2time, sfmul, sfcausint, and sfmath. This creates an RMS velocity every 12.49 meters. Intermediate traces are created using sfinterleave. The stack is computed by sorting to CMP order, removing the 250 ms delay in the modeling Ricker wavelet, NMO and stack, (Figure 6).

This processing can be run with the command:

scons stack.view

stack
Figure 6. CDP stack of 10 shotpoints.

2D modeling and basic processing with Madagascar