Surface Draping and Surface Wrapping in CASI: User-Guided Automated Technologies for Rapid Interpretation of Structural and Stratigraphic Features

James Carlson and Geoffrey Dorn
TerraSpark Geosciences, Boulder, CO

Attempts to automatically extract features from seismic volumes, using techniques such as auto-tracking and region growing algorithms, inevitably fail when confronted with noise or other anomalous conditions, due to the incapacity of these algorithms for true understanding of the data beyond simple heuristics. Manual interpretation can provide excellent results, but this is often too time-consuming to be feasible in practice. Today, interpreters typically follow a two step process wherein automatic tools are first employed to build an initial surface, followed by extensive manual cleanup to close gaps and correct for other inaccuracies.

Surface Draping and Surface Wrapping are techniques that fill the void between fully manual interpretation and automatic interpretation algorithms. Prior to the application of automated surface-fitting algorithms, the user defines a contiguous three-dimensional bounding surface that loosely approximates the structural or stratigraphic feature, paying careful attention to detail only where locally necessary to isolate the feature from artifacts in the surrounding data. This surface is then collapsed or expanded to meet the boundary of the geological feature, imaging the feature at a much higher resolution than that which could be achieved manually in a comparable amount of time. The user guides the automated process interactively, and data-aware smoothing and noise filtering parameters can be adjusted to suit the characteristics of the volume.

Surface Draping and Surface Wrapping are demonstrated in the interpretation of horizons, canyons, salt bodies and depositional systems. These techniques provide a best-of-both-worlds approach, building on the strength of human intelligence to make necessary local decisions and the capacity of the computer to rapidly image data at a very high level of detail.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas