The Improved Prediction of Permeability Variation in Selected Rotligendes Aeolian Reservoirs from the Southern North Sea Basin

LEWIS, JONATHAN J. M., and KJELL J. ROSVOLL, Imperial College, London, U.K.

An improved quantification of permeability variation in aeolian reservoir units has been developed through a combination of detailed core and outcrop minipermeameter measurements, and aerial photographic studies. Core minipermeameter measurements are

shown to be far better at defining statistically different subsurface permeability facies (lithofacies) and are used to develop reservoir zonations. A series of other useful comparisons with conventional core-plug data are made.

Outcrop minipermeameter measurements were made on the Tensleep Sandstone, Wyoming, this unit being interpreted as a good analog for parts of the Rotligendes Sandstone of the southern North Sea. Being superbly exposed with high permeabilities, it is also ideal for an outcrop based permeability study. A series of 60 ft long, vertical pseudo-wells were taken through a mixed dune-inter-dune sequence to evaluate the representativity of well data from such an environment. The results indicate that permeability statistics derived from individual wells can deviate substantially from the true permeability characteristics of such a sequence. The outcrops were also used to quantify lateral permeability variation in both dune and inter-dune facies. The results illustrate considerable spatial anis tropy of permeability variation. Larger scale patterns of dune and inter-dune sedimentation have been quantified through the mapping of lithofacies distributions on to helicopter based photomosaics, and a large, three-dimensional paleocurrent data base has been similarly developed. These data have been used to unravel the three-dimensional anatomy of a mixed dune and inter-dune sequence.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)