Modelagem estratigráfico-sedimentológica dos processos sedimentares do Sistema Turbidítico Almirante Câmara.

Abstract

Forward stratigraphic-sedimentological modelling of sedimentary systems, based on the simulation of changes of depositional variables and their interactions, has proven to be a quite promising technique applicable to reservoir characterization. In order to shed some light on how the deposition of the Almirante Câmara Turbidite System, Campos basin, evolved through the Pleistocene, was performed a series of forward modelling, using the Geological Modelling Processes (GPM) module of Petrel software (version 2020), in order to identify those depositional variables, and their interactions, capable of explaining and reproducing the architectural pattern and the facies distribution associated with this turbidite system. The Almirante Câmara Turbidite System concerns a complete modern turbidite system from a depositional point of view, being composed of different depositional domains such as: a canyon - the Almirante Câmara Canyon; a discrete channel that evolves downslope into amalgamated channels; and finally, a terminal lobe complex that spreads across the São Paulo Plateau. Parameterization applied to this turbidite system was primarily based on the interpretation of a conventional 3D-seismic grid, sedimentological and biostratigraphic information of piston cores sampled in the study area and bibliographic research. The main parameters selected the as input parameters to simulate the related turbidite deposits were: paleosurface morphology; water volume (sedimentary input); location of the sedimentary input source; hydrodymanics of the simulated flow; variation of sediment concentration in flows, flows frequency of turbidite influxes; and variations in erosional rates. Simulations results were then compared to previous studies carried out in the same area. Results obtained from the mentioned simulated parameters allowed us to identify simulation scenarios that can be proposed as a possible depositional model since it reproduces sedimentary thicknesses and stacking patterns as observed in each depositional domain of the Almirante Câmara Turbidite System, according to available geological-geophysical data. Among these, SCENARIO 6B proved to be efficient in reproducing the different depositional geometries, stratal stacking, distribution of sedimentary facies with good compatibility with the observed data, which allowed estimating that the analyzed turbiditic system was deposited from successive flows (360) with a water supply in variable regime with the values of 25,000, 75,000 and 50,000m³ released every 500 years, in a period of 20-440ka. In addition to that, simulations of transport parameters of recent turbidite deposits, such as those of the Almirante Câmara Turbidite System, may be quite valuable to the understanding of how different depositional parameters interact in turbidite systems, as well as to depositional model applicable to similar turbidite reservoirs.