Petrotype-based sampling applied in a saturation exponent screening study, Nubian Sandstone Formation, Sirt Basin, Libya

Formation properties in the Nubian Sandstone, a braided fluvial reservoir, are very variable. This is clear from porosity and permeability data cross-plots. There is no simple relationship between the two. The Petrotypebased sampling approach, where the routine core data are first plotted on an underlying, pre-determined grid, allows the selection of core plugs with a range of properties in order to carry out special core analysis (SCAL) measurements. With a few SCAL measurements, in this saturation exponent screening study, the underlying trend of the property and its controls (in this case primary depositional texture) becomes clear. This understanding can then be further exploited in the enhanced reservoir description of the Nubian Sandstone..