Effects of intermediate wettability on entry capillary pressure in angular pores

Area of Science:

• Multiphase flow
• Porous media physics
• Fluid dynamics

Background:

• Entry capillary pressure governs fluid displacement and trapped phase remobilization in porous media.
• This pressure is known to be dependent on flow rate and wettability.
• Invasion dynamics in intermediate or weakly water-wet angular pores remain ambiguous.

Purpose of the Study:

• To investigate the interface dynamics of a moving meniscus in angular pores under varying wettability conditions.
• To simulate pore invasion under drainage conditions using high-resolution computational fluid dynamics.
• To elucidate the relationship between pore geometry, wettability, and capillary pressure evolution.

Main Methods:

• High-resolution direct two-phase flow simulations using OpenFOAM software.
• Simulation of meniscus movement in a single capillary channel under constant flow rate.
• Analysis of interface dynamics in angular pores at different wettability conditions.

Main Results:

• The temporal evolution of capillary pressure during pore invasion is controlled by the interplay between the pore's half corner angle and the contact angle.
• A dip in capillary pressure is observed when deviating from pure water-wet conditions, becoming more pronounced in irregular pore cross-sections.
• This capillary pressure dip enhances pore invasion by reducing the required differential pressure.

Conclusions:

• The interaction between contact angle and pore geometry significantly impacts capillary pressure dynamics during fluid invasion.
• Deviations from ideal wettability conditions can lower the energy barrier for pore entry.
• Findings have implications for understanding and enhancing the remobilization of trapped fluids in heterogeneous porous media.