ABSTRACT: Spatial Permeability Patterns in Eolian Sediments and Their Impact on Oil Recovery

LEWIS, JONATHAN J. M., KJELL J. ROSVOLL, and PATRICK W. M. CORBETT, Heriot-Watt University, Edinburgh, Scotland

A methodology has been developed for collecting same-scale, quantitative maps of lithofacies distributions through helicopter-based photography. Medium format camera systems and video-still cameras, together with laser rangefinders and conventional sedimentological techniques, have been used on the Tensleep Sandstone in Wyoming to acquire a large database of facies distributions in an eolian system. The resultant photomosaics have been digitized to produce maps for the collection of over 10,000 permeability measurements, together with various other petrophysical measurements. All these data have then been integrated to unravel the three-dimensional sedimentological and petrophysical anatomy of transverse dune and interdune genetic units.

Analysis of this database revealed that eolian systems are characterized by directionally dependent spatial hierarchies of permeability variation, with coefficients of variation ranging from 0.2 to 0.8 at most scales of heterogeneity. These findings will be backed up by the results of a geostatistical analysis of the data (variograms, rescaled range plots, and spectral density graphs).

The database was then used to evaluate the impact of these various scales of heterogeneity on oil recovery under waterflood. This was achieved by developing pseudofunctions at sedimentologically meaningful scales (geopseudos), such scales relating to scales of homogenization for heterogeneity due to texture, cross-bedding, and bed sets. The methodology by which such scales of homogenization are determined will be outlined, as will the final results, which indicate that small-scale heterogeneity must be included if correct predictions of oil recovery are to be made.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)