BEYOND MAPPING: 3D GEOLOGIC INTERPRETATION

Our working canvas and cognitive inclinations guide our interpretation process. For field geologists, the selective exposure of 3D geologic forms is often cryptic and sometimes bizarrely displayed on equally 3D topography. Classic mapping arts range from heuristic concepts, like the “rule of V’s”, to truly impressive mental gymnastics required to imagine the capricious intersections of complex surfaces resulting in traces of contacts and faults, further compounded by the need to capture these forms as squiggly lines on a piece of paper.

Technology now provides another option: the ability to display geology in 3D, and free us from the arbitrary location imposed by our feet on the landscape and our inability to see through solid materials. What once required imagination is now more easily perceived. We can “see” stratigraphic surfaces as primary elements and more readily recognize how faults offset them. Correctly locating all the data in x, y, and z, and then viewing these data via interactive volume displays, directly reveals spatial relationships and fosters geologic comprehension.

In the subsurface world of the petroleum industry, this approach is manifest in the structural framework: a 3D network of intersecting horizons, faults and other elements. Based mostly on seismic and well data, the framework approach uses the latest interpretation software. Geoscientists can begin their visual reconnaissance with a volumetric display, and manipulate vantage points and data to quickly build a 3D mental model. The software then facilitates a transition to interpretation, still working in 3D, but where continuous geologic surfaces, and their intersections, have a primary focus. This approach replaces the classical paper map, where 3D spatial relations were represented, and often mis-represented, by structural contours.

The need for understanding geology and comprehending its 3D expression is not replaced with technology. Rather, technology provides some cognitive off-loading and accelerates the progression from visual perception to geologic interpretation. Geologists have always thought in 3D; the volumetric interface and structural framework replace the “flat map” as the leading interpretation practice. Maps still provide useful documentation, but they are derivative products rather than working models.