Permeability heterogeneity within massive Jurassic submarine fan sandstones from the Miller Field, northern North Sea, UK

Analysis of high density (5 cm sample spacing) probe permeameter data has been used to evaluate some of the basic controls on permeability heterogeneity in the Miller Field. Probe permeameter data generally show good correspondence with conventional core-plug permeability data gathered at 25 cm spacings, but record a higher frequency of permeability variation than can be resolved using conventional sampling strategies. Comparison of probe permeameter data gathered from four lithofacies recognizable in core has allowed assessment of their reservoir quality and quantification of their internal permeability heterogeneity. Geostatistical analysis of the permeability data using semivariograms suggests permeability correlation structures and periodicities are related to the frequency of sedimentary phenomena visible within core. In particular, a relationship exists between permeability correlation structure and average bedform or fining upward unit thickness, i.e. the vertical scale at which individual lithofacies packages are stacked. Geostatistical analysis of high sample-density probe permeameter data demonstrates the usefulness of permeability data gathered at more than the conventional 25 cm spacings used for core plugs. High density probe permeameter data can yield important measures of the representative geological 'structures' which could form the basis of geologically realistic two-phase flow upscaling.