InterPore2026

Experimental study on the effects of carbon dioxide on the pore structure and water affinity of the Gulong shale

22 May 2026, 14:45

15m

Oral Presentation (MS20) Special Session in Honor of Jun Yao MS20

Speaker

Jiajun Fu (Northeast Petroleum University)

Description

CO₂ injection is a key technological approach for enhancing shale oil recovery rates and achieving geological CO₂ sequestration. Investigating the effects of CO₂ on the pore structure and hydrophilicity of shale oil reservoirs under in-situ temperature and pressure conditions holds significant implications for the development of the Gulong Shale. This study investigates Gulong shale subjected to 10 days of CO₂ reaction at 25 MPa and 100°C. Pore structure before and after reaction was characterized via small-angle neutron scattering (SANS) and mercury injection capillary pressure (MICP). Hydrophilicity was assessed through contact angle measurements, water vapor adsorption experiments, and contrast-matching SANS (CM-SANS). Experiments revealed a significant reduction in water vapor adsorption capacity after CO₂ reaction, with primary adsorption decreasing substantially and secondary adsorption decreasing to a lesser extent. This primarily resulted from altered pore surface properties, which reduced the adsorption strength for water molecules and decreased the number of surface water adsorption sites. The substantial increase in water contact angle on the sample surface after reaction further indicated a marked decrease in surface hydrophilicity. Furthermore, CM-SANS revealed markedly diminished water accessibility post-reaction. Influenced by adsorption-induced swelling of clay minerals, the pore volume slightly decreased, with more pronounced reductions observed in the smaller pore size range. This may lead to compression of nanoscale pores, potentially hindering water vapor adsorption. Following CO₂ reaction, the shale may transition from hydrophilic to CO₂-friendly. This facilitates water flow within the pores, reduces throat blockage, and enhances crude oil flow. However, it may be detrimental to the structural trapping of CO₂.