The statics problem, whether short wavelength, long wavelength, residual, or trim, has always been one of the more time-consuming and problematic steps in seismic data processing. We routinely struggle with issues such as poor signal-to-noise (S/N) ratio, cycle skipping, truncated refractors, wavelets with ambiguous first arrival times, etc. Elevation variations create their own problems and impact the choice of datum—floating, phantom or recourse to a zero-velocity layer. Even if we can overcome some of these problems, we still have a “catch 22” situation in which accurate velocity estimation requires good statics, while good statics estimation requires accurate velocities. To characterize these ambiguities, we have come up the oxymoron “time-varying statics.”

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