ICE 2022


An analysis of the tectonostratigraphic evolution of the Guyana-Suriname offshore basin was carried-out from the integration of seismic interpretations, well data, bibliography and geological public information. This contribution focuses on Mesozoic evolution of the basin, which was controlled by three main global tectonic processes and local deformation responsible for the opening of a tongue-shaped depocenter towards the west and a submarine plateau, known as “Demerara”, towards the east. Each region had its particular evolution leading to different exploratory potential. The western depocenter developed, especially since the Albian, as a deep marine basin characterized by a stepped slope with canyons in the south and an abyssal plain in the north. It constitutes the main pod for the Canje Formation source rock. The Demerara plateau remained as a regional structural high during the entire evolution of the basin, where shallow marine to continental shelf sedimentation prevailed. Four regional gross depositional environment maps are presented in this paper for the following second order sequences: Valanginian-lower Albian, intra-Albian, upper Albian-Cenomanian-Turonian and Coniacian-Maastrichtian. In the Early Cretaceous, thin offshore shale intervals and turbidite systems dominated in the western depocenter. On the other hand, in Demerara, this interval was characterized by a thick carbonate platform coexisting with siliciclastic deltas coming from the south, southeast and east. During the Late Cretaceous a widespread transgressive phase affected the entire basin. Higher accommodation space developed in the western depocenter where long-distance sediment fairways have been recognized. submarine canyons and sediment bypassing characterized the shelf and slope, while in the abyssal plain turbidites and mass transport deposits interbed with shales. In the Demerara plateau, this interval is characterized by an inherited topography that controlled the sediment pathways toward northwestern mini-basins. The presence of a shelf-delta system towards the south could have acted as the main source of sediments in a long-distance sediment fairway, but other short-distance sources could also have existed. Pelagic and hemipelagic mud interfingered with mass transport deposits and turbidite systems dominated in the area. The mentioned processes, controlled the reservoir distribution and hydrocarbon prospectivity of the basin.