Three-dimensional seismic classification of salt structure morphologies across the Southern North Sea

Abstract

Post-Permian salt tectonic processes and their relationship with varied paleodepositional systems were a major controlling factor of the Mesozoic–Cenozoic basin evolution of the Southern North Sea. Detailed mapping and analysis of Zechstein salt structure morphologies is vital to conduct regional kinematic analysis and evolution of salt structures as well as understanding the relationship between thick- and thin-skinned tectonics across the basin.This study uses the supraregional Petroleum Geo-Services Southern North Sea three-dimensional seismic MegaSurvey for the systematic identification and classification of salt structure morphologies using seismic attributes and validation with regional seismic sections. The smoothed dip of maximum similarity attribute is used to highlight abrupt changes in the values of the attribute, which correspond to sudden changes in dip angle indicating faults or the edges of diapiric structures, whereas gradual changes in the attribute value coupled with the longer wavelength of structures correspond to salt anticlines. Of the 224 salt structures developed across the Southern North Sea, 119 were classified as concordant and 79 as discordant, with 26 having concordant and discordant flanks.Validation of these maps with regional seismic sections allows salt structures to be classified into salt anticlines, salt anticlines with a crestal graben, reactive diapirs, salt diapirs (walls and stocks), and salt overthrusts.This study provides guidelines for identifying different salt structure morphologies based on their seismic attribute signature, which could be applied to other salt basins around the world.