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 be attained by analog means if care is taken.In the realm of velocity determination, the computer has been used to improve calculations of expanding spread data, taking into account ray-refraction and thus providing more accurate interval velocities.Depth computations, using stratigraphy-correlated multilayer velocity models, and velocity laws derived from these more accurate interval velocities, 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.

First Page Preview

First page PDF preview
You do not currently have access to this article.