Pore Structure Development and Mechanical Degradation of Sandstone Under Thermal Loading for Geotechnical Applications

Understanding the mechanical deformation and pore characteristics of sandstone at high temperatures is crucial for optimizing its application in subsurface energy systems such as Geological carbon sequestration, underground coal gasification (UCG), and geothermal energy extraction. In this research, the impact of mild heat exposure on the mechanical properties and pore structure of sandstone from the Barakar Formation, Jharia Basin, India, was investigated. Low-pressure gas adsorption (LPGA), helium pycnometry, and water immersion porosimetry (WIP) were used to measure porosity and pore evolution quantitatively. Brazilian tensile strength (BTS) and uniaxial compressive strength (UCS) tests were used to assess the mechanical performance of the sandstone with temperatures. 

Low-Pressure Gas Adsorption (LPGA) investigations reveal the presence of silt-shaped pores in the studied samples. Both the specific surface area and pore volume increase with an increase in temperature. Additionally, WIP and He pycnometer data indicate that porosity increases with an increase in temperature, although the change is not significant. BTS and UCS data show a steady decrease in strength characteristics with rising temperatures. This degradation is attributed to the creation of microcracks, the enlargement of pre-existing pores, and thermally driven mineral changes. The study emphasizes the importance of considering thermal effects in subterranean reservoir planning and geotechnical systems, particularly in assessing long-term stability and safety in thermally active environments.