Risks inherent in the Cenozoic stratigraphic plays in basins of the Uruguayan continental margin

Abstract

Abstract The genesis and evolution of the Uruguayan Continental Margin are linked to the geological processes that resulted in the breakup of the Western Gondwana and the opening of the Atlantic Ocean. Intense hydrocarbon exploration over the last decade has identified several plays in the Mesozoic–Cenozoic sedimentary basin infill. The main exploration milestone was the drilling of the Raya x-1 well (in the Pelotas Basin), which targets an Oligocene turbidite deposit. The well encountered no hydrocarbon accumulations but has contributed to the knowledge of a frontier area and has raised questions regarding the geological risks associated with the Cenozoic prospects in the Uruguayan Continental Margin. In this study, the exploratory potential of a set of stratigraphic plays identified in the Cenozoic sedimentary succession of the Uruguayan Continental Margin basins was analysed, through the interpretation of 2D seismic sections. A significant risk appears to be related to migration and charge of the Cenozoic reservoirs from Cretaceous source rocks because of the lack of major faults and the development of thick transgressive sedimentary packages, especially in the Pelotas Basin. The best areas for vertical charge of the Cenozoic reservoirs resides on the southwest of the Uruguayan Continental Margin (distal part of the Punta del Este Basin) and in a portion of the central region (southernmost part of the Uruguayan Pelotas Basin).