Applying Fractal Theory to Characterize the Pore Structure of Lacustrine Shale from the Zhanhua Depression in Bohai Bay Basin, Eastern China

Abstract

The complexity of the shale pore structure, which can be assessed by the fractal dimension, will affect the percolation and reservoir capability of a shale; thus, the pore structure is important for shale reservoir evaluation. For the pore structure and fractal characteristics of lacustrine shale to be investigated, a combination of X-ray diffraction (XRD), total organic carbon (TOC), scanning electron microscopy (SEM), mercury-injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and Nano-CT experiments were performed on shale samples from the lower submember of the third member of the Eocene Shahejie Formation (Es3L) in the Zhanhua Depression, Bohai Bay Basin. On the basis of fractal theory, the NMR fractal dimensions of the analyzed shale samples were determined by the transversal relaxation time (T2) spectrum from the NMR experiment. The relationships between the NMR fractal dimension and mineral content, TOC, and pore structure parameter were discussed. The results indicate that the ...