What question did this study set out to answer?

This research aims to investigate how CO2 saturation affects the mechanical and thermal behavior of quartz-rich and clay-rich sandstones.

April 16, 2026

Influence of CO 2 Saturation on the Mechanical Behavior of Quartz and Clay-Rich Sandstone and Their Thermal Responses under Inert and Oxic Conditions

Key Points

This research aims to investigate how CO2 saturation affects the mechanical and thermal behavior of quartz-rich and clay-rich sandstones.
Conducted mechanical tests on Dholpur sandstone and Gondwana sandstone under different saturation levels.
Performed Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) to assess thermal stability.
Analyzed the impact of water, brine, and CO2 saturation on rock strength and thermal characteristics.
Water and brine saturation significantly decrease rock strength due to wetting–softening.
CO2 saturation minimally reduces strength, indicating greater stability under these conditions.
Gondwana sandstone exhibited reduced strength compared to Dholpur sandstone due to higher clay content.
Dholpur sandstone showed greater thermal stability with a phase transition of quartz observed at 573 °C.

Abstract

The geological sequestration of carbon dioxide (CO2) poses mechanical risks after its injection into hydrocarbon reservoirs. The mechanical and thermal stabilities of reservoir rocks are crucial for the integrity of long-term storage and the safety of injection in carbon sequestration operations. This research investigated the mechanical and thermal characteristics of Dholpur sandstone (DS) and Gondwana sandstone (GS) under different saturation and environmental conditions. The mechanical studies indicate that water and brine saturation considerably decrease rock strength due to the wetting–softening phenomenon. CO2 saturation leads to a minor decrease in strength, suggesting greater mechanical stability in CO2-saturated conditions. GS specimens revealed a significant reduction in strength relative to DS specimens related to their greater clay mineral concentration and weakening mechanisms. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) results indicate that DS specimens possess greater thermal stability than GS specimens. The DTA trend indicated that α-quartz converted to β-quartz at around 573 °C, marked by an endothermic drop during the quartz phase transition. However, a significant decrease in sample weight occurred between 470 and 540 °C because of kaolinite dehydrogenation. The results highlight the contrasting responses of quartz-rich and clay-bearing sandstones. Therefore, the experimental findings are expected to provide valuable insights and improve our understanding of the mechanical and thermal performance of reservoir rocks during carbon sequestration and enhanced oil recovery (EOR).

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