Electric pore fabric of the Nubia sandstones in south Egypt: characterization and modelling

What is it about?

This study testifies the reliability of the electric pore fabric technique applied on the Nubia sandstones in south Egypt through a comparison with pre-assigned magnetic pore fabric and permeability already measured for three perpendicular directions in these rocks. Discrepancies between the different techniques were attributed to the fact that the magnetic pore fabric technique has the ability to detect and define accurately the pore volume distribution in 3-D, whereas the electric pore fabric technique has the ability to detect the shortest paths for the electric current/fluid flow. Although the magnetic pore fabric is a bulk property, the permeability measurements and the electric pore fabric are quantifying transport properties. Both the magnetic and electric pore fabrics refer mostly to slightly and moderately anisotropic fabrics. The integration between both techniques revealed two main directions for fluid migration, swinging to the N–S and the E–W directions. One difficulty of the electric pore fabric technique is due to the surface conductivity effects either from the presence of some clay minerals or cracks. Therefore, interpreting the obtained electric pore fabric must be carried out in care for the cracked and clayey rocks. The surface conductivity effect could be accounted for by using the true formation factor for calculating the electric pore fabric parameters. The electric pore fabric technique can be compared to the 3-D permeability measurements, which show very similar directions.

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