In situ assessment of the permeability tensor of homogeneous anisotropic sedimentary rocks
Résumé
Study of geological reservoirs and is a major issue for a rational and sustainable exploitation of
underground resources (water, oil, gas ...). In order to estimate and take advantage of those
resources, it is necessary to assess the intrinsic properties of the reservoir, such as their porosity and
permeability. The latter is dependent of bedrock heterogeneity due to a variable sedimentation (e.g
sedimentary lamination, cross-bedded sediments, matrix heterogeneities) or to the presence of
fractures or faults. Theses heterogeneities can lead to anisotropic permeability properties that have
been poorly studied. To characterize this anisotropy and assess a permeability tensor, many
modeling approaches have been proposed but few studies propose to assess the permeability tensor
of a reservoir block size on the basis of in situ permeability variability measurements. In this study,
permeability tensor is determined in homogeneous anisotropic sedimentary environment (rock
samples from late Burdigalian limestones without fractures). Eight cross sections (N, NW, W, ...) were
performed on these blocks (= cut in to 8 faces), permeability measurements were realized with a field
minipermeameter (Tiny perm II). The dip of sedimentary layers was measured near to each sampled
block in order to identify possible relationships between the permeability tensor and the depositional
environment. Results show a relative consistency between sediment layer dips and orientation of
permeability tensor.