Shale pore alteration: Potential implications for hydrocarbon extraction and CO₂ storage

Area of Science:

• Geochemistry
• Petroleum Geology
• Materials Science

Background:

• Shale unconventional reservoirs are vital fossil fuel resources.
• Carbon dioxide (CO2) injection is explored for enhanced oil recovery (EOR) and carbon storage.
• The reactivity of shale with CO2 and water remains poorly understood.

Purpose of the Study:

• To investigate the reactivity of Utica Shale with CO2 and water.
• To understand how these interactions affect shale matrix properties and pore networks.

Main Methods:

• Scanning electron microscopy (SEM)
• N2 and CO2 sorption isotherms
• Mercury intrusion porosimetry (MIP)
• X-ray scattering techniques

Main Results:

• Water presence inhibits CO2 migration into the shale matrix.
• CO2 and water promote carbonate dissolution within the shale.
• Significant changes in pore scale variability occur, altering pore networks from macro- to nano-scale.

Conclusions:

• Shale matrix alterations by CO2 and water can impact fluid flow pathways.
• These changes have direct implications for oil recovery efficiency.
• The findings are critical for assessing the viability of CO2-based EOR and carbon sequestration in shales.