Rapid non-destructive mineral identification of geo-energy reservoirs using macro-lens infrared thermal imaging

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Abstract Rapid and non-destructive mineral identification is essential for understanding fluid-rock interactions and reservoir heterogeneity in deep tight reservoirs. Existing methods are still limited by complex sample preparation, low efficiency, high cost, or limited in-situ applicability. To address this gap, this study proposes a rapid mineral identification method based on macro-lens infrared thermal imaging integrated with a precision motorized translation stage. Deep tight conglomerates from the Upper Wuerhe Formation in the Mahu Sag, Junggar Basin, were used as the study samples. The apparent temperature fields obtained by infrared imaging were benchmarked point by point against TIMA mineral phase maps, and a quantitative relationship between mineral apparent temperature and effective emissivity was established through Stefan-Boltzmann-based inversion. The results show that the three dominant mineral phases, namely quartz, feldspar, and illite-smectite mixed layers, exhibit distinct thermal radiation signatures under a stable ambient environment. Quartz displays the highest apparent temperature and the lowest emissivity, consistent with its dense and smooth surface. Feldspar shows intermediate apparent temperature and emissivity, reflecting the combined effects of crystal chemistry and differential weathering. Illite-smectite mixed layers exhibit the lowest apparent temperature and the highest emissivity, mainly because of their loose and porous microstructure and the associated micro-cavity effect. These results indicate that the observed temperature contrast arises primarily from emissivity differences rather than intrinsic temperature variations among minerals. This study establishes macro-lens infrared thermal imaging as a non-contact, non-destructive, low-cost, and high-temporal-resolution approach for rapid mineral identification in tight reservoirs. The method provides a new experimental basis for efficient mineral characterization and offers significant potential for future dynamic monitoring of mineral evolution during fluid-rock interactions.