The hydrocarbon potential of the deep offshore along the Argentine volcanic rifted margin : a numerical simulation

Abstract

In the Late Jurassic/Early Cretaceous, continental break-up of Gondwana led to the opening and northward propagating of the South Atlantic. Since 135Ma, the Paraná/Etendeka continental flood basalts were emplaced, associated with seaward dipping reflector sequences (SDRS), possibly caused by the Tristan da Cunha hot spot. After break-up, thermal subsidence affected predominantly the development of the rifted volcanic continental margin, especially the elongated zone of the SDRS and a thick sedimentary column was deposited onto this transition zone between the continental and the oceanic crust where locally up to 5400m of sediments were accumulated. With the thermal calibration to available maturation data from multiple wells drilled in the nearby Colorado Basin integrated 1-D and 2-D basin modelling was applied to evaluate the thermal history of the sedimentary column. In combination with the interpretation of more than 20000km of MSC reflection/refraction seismic data and the mapping of the sedimentary units this led to a maturity-model for deposits of marine black shales, potential source rocks in the deep domain of the South Atlantic region, correlated to Cretaceous anoxic events. With the results of the 2-D basin modelling a zone favorable for the generation of hydrocarbons from proposed Aptian source rocks was defined based on the deposition and the thickness of the overburden rocks and the timing of the generation and the migration of the generated hydrocarbons was estimated. Migration pathways were modelled and possible stratigraphic oil plays were localized in onlap structures below the Danian Pedro Luro Formation along the lower continental rise in 1500 to 2000m water depth approximately 3000m below the sea bottom