Three-dimensional stratigraphic forward modeling for the prediction of facies associations and porosity in pre-salt carbonate rocks of the Sapinhoá oil field, Santos Basin, Brazil
Artigo científico
Abstract
Pre-salt reservoirs quality prediction is a complex task that demands alternative studies to better estimate its physicalproperties. The Barra Velha Formation (Aptian), in the Sapinhoá field, Santos Basin, presents carbonate rocks witha high degree of heterogeneity in its lateral and vertical distributions. Wells are confined mostly to the structuralhigh area and the seismic lacks vertical resolution, thus a forward stratigraphic modeling can be a good alternative torepresent this complex depositional system in a sub-seismic scale. The simulation has 200 time steps ranging fromthe base of the Barra Velha Formation (123 Ma) to its upper limit, at the salt base (113 Ma). The simulation useswater depth and wave energy as proxies for the facies associations distribution that fills the available depositionalspace for each time step, calculated by the backstripping method. This simulated facies association model is thenused to calculate its porosity properties with the fuzzy method, using each facies association porosity distribution andpatterns of porosity variation in space as inputs. The facies association model is compatible with the geometry anddepositional patterns observed in the seismic, with a mean well accuracy of 50%. The porosity model reproduced theproperty spatial changes, both laterally and vertically, throughout the whole study area. Both models have sub-seismicscales and are complementary results in the characterization and prediction of essential properties of future oil andgas exploratory prospects.