Seismic velocity estimation method

Abstract

A method for detecting errors in estimated seismic velocities used in a normal moveout correction of a gather of traces selected from conventional, common midpoint seismic data. Zero offset reflectivity and amplitude versus offset slope traces are derived from the NMO corrected gather. Analytic traces are calculated for the zero offset reflectivity and amplitude versus offset slope traces. The analytic zero offset reflectivity trace is multiplied by the complex conjugate of the analytic slope trace and the imaginary part of the product indicates estimated velocity errors. The velocity error indicator is used to correct the velocity estimates so that the normal moveout process may be reperformed without the errors caused by incorrect velocity estimates. Alternatively, the velocity error indicator itself is plotted on a seismic section as an indicator of characteristics of subsurface earth formations.

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