Modeling provides a major tool in interpretation. Direct modeling, the making of a synthetic seismogram to show what should be expected from a geologic model, helps in understanding what seismic features should be looked for as evidences of sought-for geologic anomalies. Inverse modeling, the making of synthetic acoustic-impedance or sonic logs from seismic data, aids in seeing the geologic significance of seismic waveshape variations near well control, especially in locating nearby stratigraphic changes suggested by well data.