ICE 2022


The continental shelf of Uruguay, in the context of the South Atlantic Ocean, shows an interesting potential for renewable energy production, taking into account the favorable wind speeds, currents and solar irradiance. In anticipation of a future global market for hydrogen, the national oil company of Uruguay is assessing the feasibility of combining offshore renewable energy with large-scale production of “green” hydrogen, mainly for export. Moreover, from the perspective of a global energy transition, it is expected that oil and gas companies take advantage of their offshore skills and gradually incorporates the production of renewable and low carbon energies. On such a project, geological and geophysical data from offshore oil and gas exploration and production, can be of value to address various challenges, including the long-term storage of hydrogen. In this work, the potential for underground hydrogen storage in porous media, offshore Uruguay, is assessed by identifying play elements and their competence. General conditions for geological storage are similar to hydrocarbon accumulations: a stratigraphic, structural or mixed trap, a suitable reservoir and an adequate seal to prevent fluids to escape from the trap. This analysis is restricted to shallow waters of Punta del Este and Pelotas basins, notwithstanding that floating technology would allow large-scale renewable energy production in deep water settings, in the near future. The main geological storage play identified, consists of Late Cretaceous stratigraphic pinch-out traps composed by shoreline-shelf, estuary or delta sands, sealed by thick marine shales related to a transgressive regional event in the Paleocene. The Late Cretaceous sequence can be observed on seismic to pinch out in a shoreward direction against a basement high (Polonio). In addition, the play shows lateral closure associated with differential compaction of sediments on depocenters, located on both sides of the high, which generates gentle drape structures. Those structures appear all along the shelf, NE-SW direction, from 50 up to 200 meters of water depth. In terms of competence, nearby exploratory well data evidence satisfactory properties for the potential Cretaceous reservoirs with good porosity values. Moreover, the effectiveness of the Paleocene shale seal, a key factor, is evidenced by the abrupt change in the fluid inclusions population detected in the wells, comparing Cretaceous with the Cenozoic sequences.