Dynamics of Compression-Driven Gas-Liquid Displacement in a Capillary Tube

Area of Science:

• Fluid Dynamics
• Multiphase Flow
• Capillary Phenomena

Background:

• Two-phase displacement is crucial in various natural and industrial processes.
• Understanding the dynamics of immiscible fluid interfaces in confined geometries is complex.
• Previous studies often simplified the interplay between reservoir compressibility and displacement behavior.

Purpose of the Study:

• To investigate the complex dynamics of two-phase displacement.
• To explore the influence of compression rate and reservoir volume on fluid movement.
• To identify and characterize distinct displacement regimes based on compressibility.

Main Methods:

• Experimental setup involving steady compression of an air reservoir connected to an oil-filled capillary tube.
• Development of a mathematical model to simulate displacement dynamics.
• Analysis of experimental data and model outputs to identify key parameters and regimes.

Main Results:

• Displacement dynamics are complex and depend on compression rate and reservoir volume.
• For large reservoirs, dynamics are governed by a single dimensionless compressibility number.
• Two distinct displacement regimes were identified: subcritical (quasisteady flow) and supercritical (burstlike expulsion).

Conclusions:

• The compressibility number is a critical parameter in determining two-phase displacement behavior.
• The identified regimes provide a framework for understanding and predicting fluid expulsion in such systems.
• This study offers insights into the fundamental physics of multiphase flow in capillary systems.