Three-phase threshold capillary pressures in noncircular capillary tubes with different wettabilities including
Mohammad Piri1, Martin J Blunt
1Department of Earth Science and Engineering, Imperial College, London SW7 2AZ, United Kingdom. mpiri@princeton.edu
Abstract:
We use the Helmholtz free energy balance and the Mayer-Stowe-Princen method to derive general expressions governing multiphase pistonlike displacements in noncircular capillary elements with arbitrary wettability. We take into account hysteresis in oil/water, gas/water, and gas/oil contact angles. We study both two- and three-phase systems. We find threshold capillary pressures for gas invasion into oil, oil invasion into gas, and water invasion into oil for capillaries with an irregular triangular cross section. Finally we study the effects of shape factor, oil/water capillary pressure, and oil/water and gas/oil contact angles on the threshold capillary pressure for gas invasion into oil for spreading and nonspreading systems. In many cases the threshold pressures of the three-phase displacements are not the same as those of the equivalent pseudo-two-phase displacements. It is possible that gas invasion can occur resulting in a configuration without oil layers, even if oil layers are geometrically possible. This emphasizes the distinction between geometric and thermodynamic stability-it is the latter that controls threshold pressures.
Related Concept Videos
Steady, Laminar Flow in Circular Tubes
Rise of Liquid in a Capillary Tube
Capillarity in Fluid
Surface tension is crucial to capillarity. It results from cohesive forces between liquid molecules at the liquid-air boundary, forming a skin that resists external forces. When the capillary tube...
Contact Angle
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
Surface Tension, Capillary Action, and Viscosity
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Phase Diagram


