Fluvial reservoir architecture in the Statfjord Formation (northern North Sea) augmented by outcrop analogue statistics

Outcrop data from the fluvial/incised valley systems of the Cretaceous Straight Cliffs Formation of southern Utah, USA, are applied to the subsurface fluvial reservoirs of the Statfjord Formation. Aspect ratios (width:thickness) for fluvial sandbodies have been measured from large-scale cliff exposures. This database provides the lateral extent, or width, of any fluvial sandbody, given the thickness for that sandbody and the net-to-gross of the interval in which it is preserved. This allows prediction of a probability distribution for fluvial sandbody width from one-dimensional vertical well data. The outcrop data are applied to one well in each of the Brent, Statfjord and Snorre fields, through similar stratigraphic intervals, to allow comparison of the various sandbody architectures which result from the same outcrop dataset. Various fluvial architectures are identified: from high net-to-gross and high connectivity, to low net-to-gross with low sandbody connectivity.