2-d Zo Crs Stack By Considering An Acquisition Line With Smooth Topography

The land seismic data suffers from effects due to the near surface irregularities and the existence of topography, For obtaining a high resolution seismic image, these effects should be corrected by using seismic processing techniques, e.g. field and residual static corrections. The Common-Reflection- Surface (CRS) stack method is a new processing technique to simulate zero-offset (ZO) seismic sections from multi-coverage seismic data. It is based on a second-order hyperbolic paraxial traveltime approximation referred to a central normal ray. By considering a planar measurement surface, the CRS stacking operator is defined by means of three parameters, namely the emergence angle of the normal ray, the curvature of the normal incidence point (NIP) wave, and the curvature of the normal (N) wave. In this paper the 2-D ZO CRS stack method is modified in order to consider effects due to the smooth topography. By means of this new CRS formalism, we obtain a high resolution ZO seismic section, without applying static corrections. As by-products the 2-D ZO CRS stack method we estimate at each point of the ZO seismic section the three relevant parameters associated to the CRS stack process. © 2005 Sociedade Brasileira de Geofísica.2311525BARD, B., (1974) Nonlinear parameter estimation, , Academic PressBIRGIN, E., BILOTI, R., TYGEL, M., SANTOS, L.T., Restricted optimization: A clue to a fast and accurate implementation of the common reflection surface stack (1999) Journal of Applied Geophysics, 42, pp. 143-155ČERVENÝ, V., PSENSIK, I., (1988) Ray tracing program, , Charles University, CzechoslovakiaCHIRA, P., (2003) Empilhamento pelo método Superfície, , de Reflexão Comum 2-D com topografia e introdução ao caso 3-D, Ph.D. thesis, Federal University of Para, BrazilCHIRA-OLIVA, P., HUBRAL, P., Traveltime formulas of near-zero-offset primary reflections for a curved 2-D measurement surface (2003) Geophysics, 68 (1), pp. 255-261CHIRA-OLIVA, P., TYGEL, M., ZHANG, Y., HUBRAL, P., Analytic CRS stack formula for a 2D curved measurement surface and finite-offset reflections (2001) Journal of Seismic Exploration, 10, pp. 245-262GARABITO, G., CRUZ, J.C., HUBRAL, P., COSTA, J., Common Reflection Surface Stack: A new parameter search strategy by global optimization, 71th, SEG Mtg (2001) Expanded Abstracts, , San Antonio, Texas,USAGILL, P.E., MURRAY, W., WRIGHT, M.H., (1981) Practical optimization, , Academic PressGUO, N., FAGIN, S., Becoming effective velocity-model builders and depth imagers, part 2 - the basics of velocity-model building, examples and discussions Multifocusing (2002) The Leading Edge, pp. 1210-1216HUBRAL, P., Computing true amplitude reflections in a laterally inhomogeneous earth (1983) Geophysics, 48, pp. 1051-1062MANN, J., JÄGER, R., MÜLLER, T., HÖCHT, G., HUBRAL, P., Common-reflection-surface stack - A real data example (1999) Journal of Applied Geophysics, 42, pp. 301-318MÜLLER, T., (1999) The common reflection surface stack method - seismic imaging without explicit knowledge of the velocity model, , Ph.D. Thesis, University of Karlsruhe, GermanySEN, M., STOFFA, P., (1995) Global optimization methods in geophysical inversion, , Elsevier, Science Publ. CoZHANG, Y., HÖCHT, G., HUBRAL, P., 2D and 3D ZO CRS stack for a complex top-surface topography, Expanded (2002) 64th EAGE Conference and Technical Exhibition, , Abstract of th

PULSE DISTORTION IN-DEPTH MIGRATION

When migrating seismic primary reflections obtained from arbitrary source-receiver configurations (e.g., common shot or constant offset) into depth, a pulse distortion occurs along the reflector. This distortion exists even if the migration was performed using the correct velocity model. Regardless of the migration algorithm, this distortion is a consequence of varying reflection angle, reflector dip, and/or velocity variation. The relationship between the original time pulse and the depth pulse after migration can be explained and quantified in terms of a prestack, Kirchhoff-type, diffraction-stack migration theory.59101561156

The common reflecting element (CRE) method revisited

The common reflecting element (CRE) method is an interesting alternative to the familiar methods of common midpoint (CMP) stack or migration to zero offset (MZO). Like these two methods, the CRE method aims at constructing a stacked zero-offset section from a set of constant-offset sections. However, it requires no more knowledge about the generally laterally inhomogeneous subsurface model than the near-surface values of the velocity field. In addition to being a tool to construct a stacked zero-offset section, the CRE method simultaneously obtains information about the laterally inhomogeneous macrovelocity model. An important feature of the CRE method is that it does not suffer from pulse stretch. Moreover, it gives an alternative solution for conflicting dip problems. In the 1-D case, CRE is closely related to the optical stack. For the price of having to search for two data-derived parameters instead of one, the CRE method provides important advantages over the conventional CMP stack. Its results are similar to those of the MZO process, which is commonly implemented as an NMO correction followed by a dip moveout (DMO) correction applied to the original constant-offset section. The CRE method is based on 2-D kinematic considerations only and is not an amplitude-preserving process.65397999