The Digital Computer’s Role in the Enhancement and Interpretation of North Sea Seismic Data

Abstract

The North Sea, with its complex geology and rapidly varying seismic velocities, is a highly suitable proving ground for the new digital data enhancement and computational techniques. Record quality is good although long and short period multiples often mask the desired deeper information (Permian or deeper).Considerable improvement in record quality has been attained by a combination of three or six-fold stacking and inverse time-domain or dereverberation filtering (deconvolution), as illustrated in the examples covering a representative selection of structural situations and record types (stratigraphic traps, faults, suspected reefs, and salt tectonics). The contribution of long-operator time-domain filtering is the most significant one to date of computer processing since good "brute" stacking can also he attained by analog means if care is taken.In the realm of velocity determination, the computer has heen used to improve calculations of e\l)anding spread data, taking into account ray-refraction and thus providing more accurate interval velocities.Depth computations, usmg stratigraphy-correlated multilayer velocity models, and velocity laws derived from these more accurate intervalvelocities, have been successfully carried out for over 100,000 North Sea "shotpoints" by computer and the results have been computer plotted.Computer programs are currently being perfected for such applications as automated velocity determination multichannel filtered stacking, data migration, and plotting and contouring

Geophysics in the Affairs of Mankind

“…); (2) determining the velocities from CDP data for accurate stacking, depth conversion and migration; and (3) migration of dipping reflection horizons using automated raypath techniques (Rockwell, 1967). In a paper in Geophysics, Rockwell indicated that the new art of digital geophysical data processing, although but five years old commercially, was being employed to solve these and other perplexing problems by: (1) reducing high-amplitude reverberations (multiples) within the water layer caused by the hard ocean bottom (This problem involved a combination of CDP stacking and deconvolution.…”