Abstract. This paper presents a detailed description and evaluation of a
multi-methodological petrophysical approach for the comprehensive multi-scale
characterization of reservoir sandstones. The suggested methodology enables
the identification of links between Darcy-scale permeability and an extensive
set of geometrical, textural and topological rock descriptors quantified at
the pore scale. This approach is applied to the study of samples from three
consecutive sandstone layers of Lower Cretaceous age in northern Israel. These
layers differ in features observed at the outcrop, hand specimen, petrographic
microscope and micro-CT scales. Specifically, laboratory porosity and
permeability measurements of several centimetre-sized samples show low
variability in the quartz arenite (top and bottom) layers but high variability
in the quartz wacke (middle) layer. The magnitudes of this variability are
also confirmed by representative volume sizes and by anisotropy evaluations
conducted on micro-CT-imaged 3-D pore geometries. Two scales of directional
porosity variability are revealed in quartz arenite sandstone of the top
layer: the pore size scale of ∼0.1 mm in all directions and
∼3.5 mm scale related to the occurrence of high- and
low-porosity horizontal bands occluded by Fe oxide cementation. This
millimetre-scale variability controls the laboratory-measured macroscopic rock
permeability. More heterogeneous pore structures were revealed in the quartz
wacke sandstone of the intermediate layer, which shows high inverse
correlation between porosity and clay matrix in the vertical direction
attributed to depositional processes and comprises an internal spatial
irregularity. Quartz arenite sandstone of the bottom layer is homogenous and
isotropic in the investigated domain, revealing porosity variability at a ∼0.1 mm scale, which is associated with the average pore size. Good
agreement between the permeability upscaled from the pore-scale modelling and
the estimates based on laboratory measurements is shown for the quartz arenite
layers. The proposed multi-methodological approach leads to an accurate
petrophysical characterization of reservoir sandstones with broad ranges of
textural, topological and mineralogical characteristics and is particularly
applicable for describing anisotropy and heterogeneity of sandstones on
various rock scales. The results of this study also contribute to the
geological interpretation of the studied stratigraphic units.
Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones
