Graduate Seminar – Experimental evaluation of diffusion in nanoporous media: Insights for shale production and applications for geo-storage

TU students are invited to join the School of Petroleum Engineering to hear from Professor Son Thai Daang about the reservoir quality of unconventional tight rocks.

Professor Son Thai Dang Seminar:
To assess the reservoir quality of unconventional tight rocks, permeability is often viewed as the key transport parameter. Perskin (1968) defined a general convective coefficient in porous media that incorporates both advective and diffusion terms. Previous research indicates that diffusion may dominate in nanoscale porous media. This study explores the role of diffusion in gas injection Enhanced Oil Recovery (EOR) for unconventional reservoirs. We introduce a novel NMR method using a Zirconium dioxide (ZrO2) ceramic core holder to evaluate fluid volumes in real-time during huff-n-puff (HnP) cycles with injectates like CO2 and CD4, which lack NMR signals. Rock samples from various organic-rich shale plays were characterized for porosity, micro-CT, mineralogy, and TOC. Pseudo-continuous T2 spectra were captured under a uniform magnetic field throughout the HnP cycles, with tests conducted both with and without confining stress to assess the influence of open cracks. Results showed incremental recovery during the injection phase, highlighting the significance of diffusion and stimulated surface area in the tight matrix. Recovery during production mirrored injection trends, suggesting a limited contribution from advective flows. We recommend considering diffusion rates and fractured surface areas to optimize the HnP process. Additionally, we developed electrical and NMR analyses to assess shale matrix tortuosity, enhancing the evaluation of tight reservoir quality in hydrocarbon production and seal capacity.