Abstract: Wave-Equation Migration--Two Approaches
K. Larner, L. Hatton
We like to think that conventional seismic sections represent cross sections below the earth's surface. Actually a seismic section displays data only as a passing wave-field recorded at selected points on the earth's surface. In regions of complex geology, this display may bear little resemblance to a cross section of subsurface reflectors. Migration is the technique used to transform the wave-field of a seismic section into a reflectivity display. Therefore, any seismic-migration method should relate to a solution of the scalar-wave equation--the assumed mathematical description of wave propagation in the earth's subsurface. Two very different approaches in vogue are derived from different forms--integral and differential--of this equation. This paper focuses primarily o comparison migrations of both synthetic data and of marine and land profiles. For good data of modest dip, the two approaches produce results which are remarkably similar despite their very different concepts and realizations. This outcome is very encouraging, as it increases confidence in the rationale behind migration. For poorer data of modest dip, the solutions based on differential forms of the scalar-wave equation have noticeably superior signal-to-noise compared with their integral-form counterparts. The seismic-trace spacing (receiver group interval) is found to play different, but fundamental, roles in governing the accuracy and quality of both types of migration.
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC