The Permeability of Shale Exposed to Supercritical Carbon Dioxide

The impact of supercritical carbon dioxide (SC-CO2) on shale gas reservoir permeability is at the heart of this study. Permeability, a pivotal factor in tight reservoir rocks, dictates the fluid flow and overall yield from these reservoirs, and in turn, determines their commercial viability. Utilizing SC-CO2 in shale gas extraction not only augments the efficiency of fracturing but also provides a dual advantage in the form of potential geological CO2 storage.

An intriguing observation made was that the relationship between permeability and gas pressure did not follow a straightforward trajectory. Instead, a segmented trend was noticed, particularly pronounced near the supercritical state. Subsequent investigations involving shale specimens immersed in SC-CO2 revealed a marked increase in permeability post-treatment, linearly dependent on SC-CO2 pressure. Furthermore, advanced techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), highlighted that SC-CO2 initiates complex chemical interactions with shale minerals, thereby enhancing permeability by broadening the gas seepage pathways.