Element migration in turbidite systems: Random or systematic depositional processes?

In turbidite settings, channel sand bodies stack laterally and vertically as a function of turbidite story confinement degree. Therefore, we can establish a simple mathematical relationship between these parameters to represent and model complex reservoir features. The morphology of eight well-imaged turbidite complexes from west Africa (from upper Oligocene to Pleistocene deposits) was studied to improve the understanding of their evolution and to assess depositional processes. Measurements of individual channels are treated statistically and compared with channel story characteristics. Based on this geometric analysis, we establish a relationship between the degree of channel story confinement and the stacking architecture of channelized sand bodies. This relationship allows an assessment of reservoir architecture and connectivity for different depositional settings characterized by channel story confinement. Less-confined channel stories characterized by lateral migration patterns with low vertical amalgamation have a tabular amalgamated architecture where connectivity is related to channel margin heterogeneities. As confinement increases, downdip and vertical movement components increase, leading to ribbon platform and vertical amalgamation of sand bodies. Resulting reservoir characteristics are highly variable along channel stories, depending on downdip and vertical component ratios. According to our observations, the degree of confinement exerts an important control on turbidite flows and the ultimate distribution and architecture of sedimentary bodies.