Advanced Applied Geology

Advanced Applied Geology

Hydrocarbon-generation potential of Upper Triassic–Middle Jurassic coal-bearing strata in the Parvadeh Mine, Tabas, east-central Iran

Authors
Mohammad Eskandari 1
Maryam Khosravi 1
Amir Abbas Jahangard 2
Mohammad Ali Salehi 2
Morteza Tabaei 1
1 Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran
2 Department of Geology, Faculty of Sciences, University of Isfahan, Isfahan, Iran
10.22055/aag.2026.51483.2555
Abstract
This study aimed to evaluate the gas-generation potential of the coal-bearing strata in the Parvadeh Mine, Tabas, east-central Iran. Borehole core samples were collected from three geological units: the Nayband Formation (Upper Triassic Qadir Member), the Ab-e-Hajji Formation (Early Jurassic), and the Parvadeh Formation (Middle Jurassic). Thermal maturity within the studied succession increases progressively with depth, beginning at the early oil window in the Parvadeh Formation. This trend reaches the peak oil-generation stage in the Ab-e-Haji Formation and ultimately progresses beyond the peak oil window into the wet-gas generation stage in the Nayband Formation. Rock-Eval pyrolysis results show that the Ab-e-Haji Formation has relatively low total organic carbon, weak to moderate hydrocarbon-generation potential, a low hydrogen index, and a high oxygen index, consistent with Type III kerogen deposited under oxidizing to sub-oxidizing conditions. In contrast, the Nayband Formation exhibits high TOC values, elevated S2, high HI, and relatively lower OI. Its kerogen is mainly Type III/II and Type III of terrestrial origin, indicating very good to excellent potential for dry-gas (methane) generation. Shallow intervals of the Nayband Formation fall within the oil window, whereas deeper intervals reach the condensate to wet-gas generation stage. Overall, the results indicate that the Nayband Formation is the most thermally mature and gas-prone unit within the studied succession, and drilling may be associated with an increased risk of sudden methane release and potential explosion hazards.
Keywords
Organic petrography
Thermal maturity
Rock-Eval pyrolysis
Gas-generation potential
Tabas Basin
Subjects
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Advanced Applied Geology
Volume 16, Issue 1
Spring 2026
Pages 38-56