1：Experimental Design and Method Selection:

The study utilized terahertz (THz) imaging to measure the dielectric properties of oil shale samples from Huadian and Beipiao with different oil yields. The heterogeneous distribution of organics on the oil shale surface was evaluated by THz amplitude images.

2：Sample Selection and Data Sources:

Oil shale samples were gathered from Huadian in Jilin province and Beipiao in Liaoning province. The oil yield of organic-rich Huadian oil shale is ~10%, while that of Beipiao oil shale is ~5%.

3：5%. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: A reflection THz imaging system with the effective frequency range 0.1-2 THz and the spatial resolution below 0.2mm was used. The source of THz wave was generated in a LiNbO3 crystal by optical rectification and phase matching.

4：1-2 THz and the spatial resolution below 2mm was used. The source of THz wave was generated in a LiNbO3 crystal by optical rectification and phase matching. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Before the THz measurement, oil shale slices were cut from each block at the dimensions 2×2×0.1 cm3 with the plane parallel to the beddings. The THz scanning was performed under nitrogen atmosphere with the temperature 294.1 K and the humidity 0.0%.

5：1 cm3 with the plane parallel to the beddings. The THz scanning was performed under nitrogen atmosphere with the temperature 1 K and the humidity 0%. Data Analysis Methods:

5. Data Analysis Methods: Reflective THz pulse at different pixel were measured and recorded. Peak amplitude of each waveform was simultaneously extracted and reconstructed with variant colors on the computer.