The 9th International Conference on Energy, Resources, Environment and Sustainable Development (ERESD 2022)

Tectonically deformed coal (TDC) is closely related to gas outbursts. Since TDC exploration is an essential objective for coalfield exploration, it is of great significance to study the petrophysical properties of TDC. In this study, 17 samples of different types of TDC from the Huaibei coalfield were collected, and ultrasonic testing was used to measure their petrophysical parameters, including P- and S-wave velocities and their derived petrophysical parameters (V_P/V_S, P-wave impedance, and S-wave impedance). Undeformed coal and TDCs with different deformation types (Brittle, Shear, and Plastic deformations) show significant differences in their petrophysical parameters, and one can differentiate them with cross-plot analysis. Therefore, the changes in petrophysical parameters are good indicators to determine the type of coal deformation. However, the TDCs with the same deformation type have similar petrophysical parameters; it is not easy to distinguish them. Instead of direct classification, TDCs can be classified into at least five types with high accuracy using principal component analysis and cluster analysis. The research results can provide physical parameter guidance for the geophysical exploration of TDCs

Tectonically deformed coal; Ultrasonic testing; Petrophysical parameters; Clustering classification; Principal component analysis