Figure 1

OIRD images of shale core when the scan direction is parallel to the bedding of shale.
(a) 2-D image of Re{Δp − Δs}. A number of striations are obtained parallel to the 1-mm side and perpendicular to the 2-mm side. (b) 2-D image of Im{Δp − Δs}. A similar number of striations is obtained parallel to the 1-mm side and perpendicular to the 2-mm side but show different intensities compared with (a). (c) 3-D images of Re{Δp − Δs} of six selected regions with areas of 100 μm × 100 μm. Within the six regions, three are from (a), and the others are from (b). The agreement between the OIRD signals and the bedding properties of the shale is validated.