3D internal structure of rift basins from scaled physical models

Abstract

Three-dimensional (3D) geometries and internal structures of rift basins were controlled by extension direction and pre-existing structure beneath the rift basin. The study about 3D fault surfaces in the rift basins will help to understand the evolution occurring into the rift basins and the pre-existing structure controlling the geometry of rift basins. This study constructed the 3D digital models from a series of cross-section images of the scaled physical models (orthogonal rift model and oblique rift model) of the rift basins and compared the internal structure of both models. A new technique for 3D fault model construction was developed from using the combination of image-seismic conversion software (Kogeo®), seismic interpretation software (OpendTect®, Petrel 2014) and structural analysis software (MoveTM). The orthogonal and oblique rift model are characterized by segmented rift-border faults having orientation to be parallel to the pre-existing structure beneath the rift basin, whereas intra-rift faults having the orientation to be sub-perpendicular to perpendicular to the extension direction. Dip angles of both fault sets decrease with depth. Fault displacements in the oblique rift model are generally higher than that in the orthogonal rift model. Maximum displacement is found in the intra-rift faults forming the basin depocenter in both models. Fault linkages can be easily observed in the oblique rift model than the orthogonal rift model. The results were compared with the fault systems in the examples of natural rift basins and can be used to apply to petroleum system about fault trap and migration pathways of hydrocarbon.