Effect of grain size distribution on interfacial area-saturation curves in multiphase flow through porous media

Abstract:

Immiscible displacement (multiphase flow) through porous media provides key information about contaminant transport and/or remediation mechanisms in environmental engineering and geosciences. For instance, in groundwater contamination oil can have a variety of trapped configurations in the pore-space at a particular value of water saturation. This leads to formation of unique interfacial area-water saturation curves that may vary across different porous media properties such as grain size distribution. It is important to understand how the interfacial area-saturation curves form at the pore-scale during oil invasion (drainage) and water re-injection (imbibition). The objective of this work is to quantify how grain-size distribution affects the interfacial-area saturation curves during drainage and imbibition of oil-water through porous media. A multi-phase lattice Boltzmann model is used to simulate the drainage and imbibition in an ensemble of 2D porous domains for 3 groups: well sorted realizations, intermediate realizations, and poorly sorted realizations. We observe that the peak interfacial area occurs when the defending fluid is at 0.20-0.30 for drainage and imbibition, regardless of grain-size distribution. During drainage, the interfacial area increases with decreasing water saturation, across all three groups, until a peak is reached after which further reduction in water saturation results in a sharp decrease in interfacial area. The opposite trend is seen in imbibition, the interfacial area increases with increasing water saturation and reduces after the peak interfacial area is acquired. On average, the value of the peak interfacial area across the three groups remains the same in drainage and imbibition. In this presentation, we will compare results from three soil types to elucidate how grain-size distribution affects the drainage and imbibition sequences. The results of this work can help improve the aquifer and soil remediation efforts in different soil types.