Germination

Porous medium

Physics

Geology

Wetting

Two-phase flow

Composite material

Geotechnical engineering

Work (physics)

Materials science

Capillary action

Instability

Lattice Boltzmann methods

Imbibition

Viscous fingering

Micromodel

Flow (mathematics)

Capillary pressure

Mechanics

Botany

Porosity

Biology

Fluid dynamics

Thermodynamics

Water Resources Research

Imbibition in porous media plays a crucial role in many engineering and industrial processes, such as enhanced oil recovery and groundwater contamination remediation. Due to the instabilities at the two‐phase interface, the defending fluids in these processes are often not effectively displaced. Therefore, it is of great significance to study imbibition in natural rocks at the pore scale, especially under the completely wetting and viscously unfavorable conditions due to their contribution to interfacial instability. In this work, numerical simulations of forced imbibition in three natural rocks are carried out at four different injection rates based on the color lattice Boltzmann model. The interfacial evolution and in situ fluid distribution are analyzed from several perspectives. Results show that as the capillary number, expressed in logarithms, varies from −2.5 to −4.0, the flow characteristics of the invading fluid change from leading films on the solid surface of large pores to corner flow along the pore corners of pores with different sizes, the dominant pore filling event changes from ganglion dynamics to snap‐off trapping, and the morphology of the displacement front changes from viscous fingering to a rough but uniform characteristic. These changes at the two‐phase interface determine the fluid distribution and fluid structure, controlling the microscopic displacement efficiency, interface area and fluid connectivity. This work systematically investigates for imbibition of the local and global flow physics and dynamics, the mechanical nature and the resulting effects of interfacial instability under unfavorable conditions, which help to deepen our understanding of the microscopic mechanism of forced imbibition.

Systematic Investigation of Corner Flow Impact in Forced Imbibition