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ABSTRACT: Retrieval Mapping: Integrated Structural/Stratigraphic Analysis Applied to the Bonaparte Gulf, Northwest Australia

TOBIAS, STEVEN, BHP Petroleum

Retrieval mapping is the term that describes a dynamic workstation-based methodology for seismic interpretation. It smoothly combines the two parallel tasks of sequence stratigraphic analysis and structural mapping.

The central goal of retrieval mapping is for the interpreter to always view and digitize seismic images which have been palinspastically-restored. This reverses the chronology of conventional mapping, where horizons are restored only after they have all been digitized. This goal is approached by replacing the interpreter's usual frame of reference (i.e., sea level) with a series of progressively deepening datums, ideally "flattened" flooding surfaces.

This accomplishes three things. First, the removal of post-depositional structuring means that horizon curvature takes on purely stratigraphic significance. Consequently, "picking data" moves from the realm of the structural to that of the stratigraphic. Second, the geometries of older system tracts become undistorted, meaning that isopach information can be displayed and mapped "real-time", before structural maps are even started. This allows the interpreter to quickly integrate seismic and well facies with depositional geometries, yielding higher quality paleogeographic maps. Third, image processing (i.e., compression) can be optimized for each datum so as to enhance subtle features.

Retrieval mapping will only reach full fruition with decompacted, palinspastically restored, depth migrated seismic images. However in certain areas it can already serve as a viable mapping strategy. One such area is in the Bonaparte Gulf, offshore northwest Australia. It is characterized by a thick Paleozoic and Mesozoic section deposited under a complex interaction of eustacy, tectonism and sediment supply. Examples from recent 2D BHP data emphasize the insight and speed gained with this approach.

 

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)