Imaging of compositional gradients during in situ emulsification using X-ray micro-tomography

Area of Science:

• * Porous media science
• * Colloid and surface chemistry
• * Multiphase flow dynamics

Background:

• * Emulsification in surfactant/oil/water systems is crucial for porous media applications.
• * Understanding the interplay of flow, mixing, and kinetics is key to controlling emulsification.
• * Direct visualization of rapid emulsification and compositional gradients in 3D pore space is challenging.

Purpose of the Study:

• * To visualize and quantify the dynamics of in situ emulsification within porous rock under flow conditions.
• * To investigate the kinetics of emulsification and the evolution of compositional gradients.
• * To develop and apply advanced imaging and image processing techniques for multiphase flow analysis.

Main Methods:

• * Integration of a flow unit with synchrotron X-ray computed micro-tomography (XCMT) for non-destructive 3D imaging.
• * Time-resolved scanning at intervals of 7-60 seconds during fluid injection.
• * Development of advanced image processing to correlate grey levels with local oil content in emulsified regions.

Main Results:

• * Emulsification within the porous rock occurred within seconds of surfactant injection.
• * Compositional gradients were observed in the emulsified phase, indicating localized oil mobilization and solubilization.
• * Significant oil displacement was observed within seconds, while gradients persisted for minutes.

Conclusions:

• * Fast XCMT enables real-time visualization of rapid emulsification processes in porous media.
• * The study demonstrates a sequence of oil mobilization and solubilization driven by flow and surfactant action.
• * This methodology provides insights into interfacial phenomena in applications involving in situ emulsification.