The fractal microstructure of ancient sedimentary rocks

Small‐angle neutron scattering (SANS), ultra‐small‐angle neutron scattering and scanning electron microscopy (SEM) were used to analyze the pore‐fabric interface in a 1400 million years old shale. The pore‐rock fabric interface is a surface fractal (of fractal dimension 2.82) over three orders of magnitude of the length scale and ten orders of magnitude in intensity (macroscopic differential cross section range 10−1– 109 cm−1). Both SANS and SEM indicate similar fractal dimension for scales less than 4 µm and a breakdown of fractal properties for scales larger than 4 µm.