Porethroats

Pore throats are the narrow passages that connect larger voids within a porous medium, such as rocks, soils, ceramics, and membranes. They play a key role in determining how fluids move through the material by capillary forces and by providing preferential pathways. The sizes, shapes, and connectivity of pore throats influence the overall permeability and the capillary pressure behavior of the medium.

In geology and petrophysics, the pore body is the larger cavity and the throat is the constricted neck that links neighboring pores. Pore throat diameter is generally smaller than pore body dimensions and often controls the onset of flow for a given fluid. A narrow throat can trap immiscible fluids and create residual saturations despite the surrounding pore space becoming accessible.

Characterization methods include mercury intrusion porosimetry, which infers throat size distributions from intrusion pressures using capillary pressure concepts; microcomputed tomography and other imaging techniques can resolve throat geometries directly. Porous media are often represented as pore-network models with pores as nodes and throats as links. Real throat geometry is complex, and factors such as throat shape, wettability, and contact angle affect measurements and interpretation.

Applications span oil and gas reservoir management, hydrogeology, filtration, and materials science. Pore throat distributions influence capillary pressure curves, breakthrough behavior, and residual saturations, affecting extraction efficiency, groundwater movement, and filtration performance. Understanding pore throats aids in predicting fluid storage and transport properties, as well as the design of porous materials with tailored flow characteristics.