The core of OpendTect SSIS is the chrono-stratigraphy. This is a set of densely sampled 2D or 3D horizons that follow seismic events. Each chrono-stratigraphic horizon is a geologic time line. In OpendTect SSIS we typically create hundreds of chrono-stratigraphic horizons per sequence, bounded by conventionally mapped horizons. Chrono-stratigraphy can be created in two different modes: model-driven and auto-tracking. The three model-driven types are: stratal slicing (aka proportional slicing), parallel to upper - and parallel to lower horizon. The two auto-tracking types are: data-driven, in which case we follow the local dip / azimuth from the steering cube and event driven, in which case we auto-track all maxima, minima and zero-crossings in the data.

With the chrono-strat slider we can interactively add/remove chrono-stratigaphic horizons from a display of a seismic section. In that way we can reconstruct the history of deposition in (relative) geologic time. This tool is also extremely useful in cross-correlating events between wells.

The Wheeler transformation is another key feature of OpendTect SSIS. A Wheeler transformation is a flattening of seismic data according to the calculated chrono-stratigraphy. In the Wheeler domain we see when (in relative geologic time) and where (spatially) events were deposited, how the depositional center shifted over time (basin-wards or landwards) and how events are related in time. Gaps in the Wheeler domain are caused either by erosion or non-deposition

OpendTect SSIS supports an interpretation module for systems tracts interpretation and to extract important stratigraphic boundaries from the interpreted data. The module automatically reconstructs the relative base level curve and supports all popular sequence stratigraphic models used in the industry.

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