Artículos de revistas
Seismic Constant-velocity Remigration
Registro en:
Geophysics. , v. 62, n. 2, p. 589 - 597, 1997.
168033
2-s2.0-0031103434
Autor
Schleicher J.
Hubral P.
Hocht G.
Liptow F.
Institución
Resumen
When a seismic common midpoint (CMP) stack or zero-offset (ZO) section is depth or time migrated with different (constant) migration velocities, different reflector images of the subsurface are obtained. If the migration velocity is changed continuously, the (kinematically) migrated image of a single point on the reflector, constructed for one particular seismic ZO reflection signal, moves along a circle at depth, which we call the Thales circle. It degenerates to a vertical line for a nondipping event. For all other dips, the dislocation as a function of migration velocity depends on the reflector dip. In particular for reflectors with dips larger than 45°, the reflection point moves upward for increasing velocity. The corresponding curves in a time-migrated section are parabolas. These formulas will provide the seismic interpreter with a better understanding of where a reflector image might move when the velocity model is changed. Moreover, in that case, the reflector image as a whole behaves to some extent like an ensemble of body waves, which we therefore call remigration image waves. In the same way as physical waves propagate as a function of time, these image waves propagate as a function of migration velocity. Different migrated images can thus be considered as snapshots of image waves at different instants of migration velocity. By some simple planewave considerations, image-wave equations can be derived that describe the propagation of image waves as a function of the migration velocity. The Thales circles and parabolas then turn out to be the characteristics or ray trajectories for these image-wave equations. 62 2 589 597 Bevc, D., Black, J.L., Palacharla, G., Plumes: Response of time migration to lateral velocity variation (1995) Geophysics, 60, pp. 1118-1127 Black, J.L., Brzostowski, M.A., Systematics of time migration errors (1994) Geophysics, 59, pp. 1419-1434 Chun, J.H., Jacewitz, C.A., Fundamentals of frequency domain migration (1981) Geophysics, 46, pp. 717-733 Cognot, R., Thore, P., Haas, A., Tying seismic to well data using structural uncertainties (1995) Spring Symposium of the Geophys. Soc. of Tulsa, , Soc. Expl. Geophys Fomel, S.B., Method of velocity continuation in the problem of seismic time migration (1994) Russian Geology and Geophysics, 35 (5), pp. 100-111 Hubral, P., Schleicher, J., Tygel, M., A unified approach to 3-D seismic reflection imaging - Part I: Basic concepts (1996) Geophysics, 61, pp. 742-758 Hubral, P., Tygel, M., Schleicher, J., Seismic image waves (1996) Geophys. J. Internat., 125, pp. 431-442 Iversen, E., Derivatives of reflection point coordinates with respect to velocity parameters (1995) Workshop on Seismic Waves in Laterally Inhomogeneous Media, , Třešt', Prague University Jaya, M.S., Schleicher, J., Hubral, P., Post-stack time-domain remigration (1996) 58th Ann. Internat. Mtg., Eur. Assn. Expl. Geophys., pp. X017 Larner, K., Beasley, C., Cascaded migration: Improving the accuracy of finite-difference migration (1987) Geophysics, 52, pp. 618-643 Liptow, F., Hubral, P., Migrating around in circles (1995) The Leading Edge, 14, pp. 1125-1127 Rocca, F., Salvador, L., Residual migration (1982) 52nd Ann. Internat. Mtg., Soc. Expl. Geophys. Rothman, D.H., Levin, S.A., Rocca, F., Residual migration: Applications and limitations (1985) Geophysics, 50, pp. 110-126 Stolt, R.H., Migration by Fourier transform (1978) Geophysics, 43, pp. 23-48 Tygel, M., Hubral, P., Constant velocity migration in the various guises of plane-wave theory (1989) Surveys in Geophysics, 10, pp. 331-348 Tygel, M., Schleicher, J., Hubral, P., A unified approach to 3-D seismic reflection imaging - Part II: Theory (1996) Geophysics, 61, pp. 759-775