Abstract: Seismic Stratigraphy: New Kind of Geophysical Interpretation

Milton B. Dobrin

Since the earliest days of seismic exploration, the reflection method has been much more successful in locating structural entrapments of oil and gas than in finding stratigraphically trapped accumulations. Limitations in the resolution of the seismic pulse make very difficult the mapping of stratigraphic features (other than reefs) with the precision necessary to specify a successful drilling location. Improvements in seismic techniques, fortunately, are increasing the resolution of the seismic method and making possible location of some productive stratigraphic features that previously were undetectable; yet the basic limitation remains.

But the seismic-reflection method has great potential, little recognized until now, for aiding the geologist in his initial assessment of an area as a prospective source of stratigraphic oil and gas. By proper analysis of reflection patterns one can recreate depositional history and deduce environments of deposition in parts of the geologic section of exploration interest. These patterns make possible recognition of shoreline movements such as transgressions and regressions, deltas, and other prograding types of deposition, unconformities and other erosional truncations, and eustatic movements. Such studies have been made by seismic interpreters on an individual basis for many years, but only recently has this approach become systematized to the extent that it can be presented in teac able form.

Using these new criteria, one can reconstruct depositional history from reflection patterns and thus identify favorable environments for hydrocarbon accumulation in areas where no drilling information is available.

AAPG Search and Discovery Article #90976©1976 AAPG-SEPM-SEG Pacific Section Meeting, San Francisco, California