3D GEOMETRIC MODELING OF SALT TECTONICS, SEDIMENT DISPERSAL PATHS, ACCUMULATION HISTORY, AND HYDROCARBON MIGRATION THROUGH TIME

Progressive active salt diapir growth impacts sediment dispersal paths, accommodation space for marine deposits, and hydrocarbon migration routes. Forward modeling of the shape change of horizons through time, accompanying the salt body growth, provides insight into the interplay of structural development, sediment accumulation and hydrocarbon migration history. The forward modeling displays the sediment accumulation history of a reservoir unit in a particular time interval and subsequent potential hydrocarbon migration paths, as well as the strain history.

A case example in the vicinity of a complex salt body in the Gulf of Mexico, illustrates the concepts and techniques of the 3d modeling through time. The present day shape of several horizons and the salt are well defined by seismic data. Step-by-step restoration that includes decompaction, unfolding, and isostasy provides the basis for forward modeling.

Forward modeling of step-wise filling of accommodation space in a specific time interval shows the most likely channel paths of turbidite systems, and areas of ponded turbidite deposition. Reversing the restoration steps illustrates the sequence of deformation of the turbidite section resulting from salt withdrawal and lateral movement. For a time step when generation and migration of hydrocarbons was occurring, hydrocarbon migration pathways modeled onto the horizon tops illustrate the relative layout of the earlier deposition patterns compared with the later positions of structures that control migration routes. The combined restoration and forward modeling can thus provide valuable insight into the relative risk of potential hydrocarbon traps. Lastly, different strain values can be calculated for the horizon tops (or volumes) while deforming the surfaces from their initial, nearly flat geometry to their present day shape. These values can aid in understanding of fractures in the present day deformed state.