SEISMIC CHARACTERIZATION OF INTERNAL SALT CYCLES: A CASE STUDY IN THE SANTOS BASIN, BRAZIL

Abstract

The exploration of pre-salt reservoirs in the Santos Basin, Brazilian Offshore, requires innovative approaches to improve the quality of reservoir seismic images below large salt bodies, helping to enhance the depth predictions and to improve security for drilling operations. Salt is a general term for evaporites that may present an enormous complexity. Outcrop and experimental data show that evaporites precipitate in a controlled and defined order, respecting increasing brine salinity. When analyzing the Ariri Formation (salt section) in the Santos Basin we recognize several evaporation salt cycles, indicating climatic and tectonic controls. In this work, we identify the salt cycles in wells and integrate those with the seismic data as low-frequency events to create detailed velocity models. Our results confirm that the incorporation of the salt cycles reduces the average mismatch of depth positioning, consequently, providing reliable volumetric estimations.