Three-phase flow through rough-walled fractures: An experimental investigation of relative permeabilities under varying saturation histories

Abstract

Relative permeabilities are essential for assessing subsurface flow performance for applications such as hydrocarbon recovery, enhanced geothermal, CO₂ storage, Hydrogen geo-storage, and water resources management. This study presents a comprehensive macro-scale experimental investigation of three-phase relative permeabilities in a rough-walled fracture across a broad range of saturation histories. The findings indicate that the brine relative permeability was primarily dependent on its saturation level. In contrast, oil relative permeability exhibited a pronounced dependence on saturation history, showing a quadratic correlation at low oil saturations (dominated by layer flow) and a quartic relationship at high saturations (governed by oil-filled fracture elements). Gas relative permeability was influenced by both its own saturation and saturation history. Higher flow rates were observed to enhance the relative permeabilities of both oil and gas. These trends are linked to changes in fluid configurations and transport dynamics within the fracture aperture.