The Impact of Sub-Resolution Porosity of X-ray Microtomography Images on the Permeability

Cyprien Soulaine (1) , Filip Gjetvaj (2) , Charlotte Garing (2) , Sophie Roman (1) , Anna Russian (3) , Philippe Gouze (2) , Hamdi Tchelepi (4)

1 IMFT - Institut de mécanique des fluides de Toulouse
2 Géosciences Montpellier
3 IDAEA - Institute of Environmental Assessment and Water Research
4 Stanford University

There is growing interest in using advanced imaging techniques to describe the complex pore-space of natural rocks at resolutions that allow for quantitative assessment of the flow and transport behaviors in these complex media. Here, we focus on representations of the complex pore-space obtained from X-ray microtomography and the subsequent use of such ‘pore-scale’ representations to characterize the overall porosity and permeability of the rock sample. Specifically, we analyze the impact of sub-resolution porosity on the macroscopic (Darcy scale) flow properties of the rock. The pore structure of a rock sample is obtained using high-resolution X-ray microtomography (3.163μm3/voxel). Image analysis of the Berea sandstone sample indicates that about 2 % of the connected porosity lies below the resolution of the instrument. We employ a Darcy–Brinkman approach, in which a Darcy model is used for the sub-resolution porosity, and the Stokes equation is used to describe the flow in the fully resolved pore-space. We compare the Darcy–Brinkman numerical simulations with core flooding experiments, and we show that proper interpretation of the sub-resolution porosity can be essential in characterizing the overall permeability of natural porous media.

Mots clés: Sub-resolution porosity; Microporosity Pore-scale simulation; Darcy–Brinkman formulation; Berea sandstone; Microtomography

Domaines: Physique [physics]

Cyprien Soulaine, Filip Gjetvaj, Charlotte Garing, Sophie Roman, Anna Russian, et al.. The Impact of Sub-Resolution Porosity of X-ray Microtomography Images on the Permeability. Transport in Porous Media, 2016, 113 (1), pp.227 - 243. ⟨10.1007/s11242-016-0690-2⟩. ⟨hal-01692755⟩