Pore-Scale Investigation of Dynamic Immiscible Displacement in Layered Media using Synchrotron X-ray Microtomography

Area of Science:

• Geochemistry
• Environmental Engineering
• Fluid Dynamics

Background:

• Understanding multiphase flow in porous media is crucial for chemical and environmental engineering.
• The influence of geological heterogeneity on fluid dynamics at the pore scale is not well understood.

Purpose of the Study:

• To experimentally investigate the pore-level dynamics of immiscible fluid displacement and entrapment in layered porous media.
• To analyze the impact of geological heterogeneity, specifically sand grain size variations, on fluid saturation and morphology.

Main Methods:

• Utilized time-lapse synchrotron X-ray microtomography for pore-level visualization.
• Conducted drainage-imbibition experiments in an unconsolidated layered sand pack (coarse and fine sand zones).
• Developed a novel method to track immiscible fluid variations within individual pores over time.

Main Results:

• Observed distinct differences in fluid saturation and nonwetting fluid (oil) morphology between coarse and fine sand zones during imbibition.
• In coarse zones, oil clusters fragmented; in fine zones, oil clusters remained connected across multiple pores.
• Noted an increase in the oil-water interface surface area during imbibition, suggesting enhanced mass transfer potential.

Conclusions:

• Geological heterogeneity profoundly affects immiscible fluid displacement and entrapment at the pore scale.
• Pore size and connectivity are key factors governing multiphase fluid dynamics in layered media.
• Insights into pore-level fluid behavior can inform more effective environmental remediation techniques.