Impacts of halokynesis in seismic interpretation and generation of the top salt surface in a distal portion of the Santos Basin

Abstract

Studies on evaporitic rocks are of great importance for the oil and gas industry as they can create traps and seals for the hydrocarbon accumulations. Also, salt high ductility allows the formation of complex structures associated with halokinesis posing thus major challenges for imaging the rocks at their flanks and below the structures. This paper discusses the effects of salt tectonics on post-salt layers and the difficulties in interpreting the top salt surface in a particularly complex area of the Santos Basin. The available seismic and migration velocity model data are from an area located in the distal portion of the Santos Basin where the existing salt structures had a profound effect on the post-salt layers. Complex salt structures were formed in this area due to the intrinsic characteristics of salt rocks as it flew away from the terrigenous depocenters, pushed in the Atlantic Ocean realms. Structures such as overhangs are common and sometimes difficult to be mapped. Their geometry generates multiple points with the same latitude and longitude, but at different depths as they are interpreted and thus represent a challenge for current surface interpolation algorithms. A workflow is proposed to optimize multi-z surfaces generation from the top of the salt layer from the interpretation this surface in conjunction with the analysis of the migration velocity model. Finally, a zonation map of the salt walls, mini-basins, salt domes, overhang and salt window in the region is presented.