An Experimental Study of the Factors Influencing Apparent Wetting Phase Residual Saturation in Dynamically Drained Porous Media

作者：Naghavi Benyamin; Kibbey Tohren C G^*

来源：Transport in Porous Media, 2014, 101(1): 149-160.

DOI：10.1007/s11242-013-0237-8

• Residual saturation
• Unsaturated soils
• Porous media
• Drainage

When a porous medium drains, the wetting phase saturation in the medium [the fractional volume of wetting phase (often water) in the pores] is typically observed to approach a minimum value, referred to as the wetting phase residual saturation (). While many simulators of unsaturated and multiphase flow assume to be a single value for a given fluid and porous medium system, there is considerable evidence that may be a dynamic property, with its value a function of the rate of saturation change. The objective of this work was to study this relationship, with emphasis on understanding the effect of drainage rate on the apparent residual () at moderate capillary pressures and over short time frames. Dynamic unsaturated drainage experiments were conducted to explore this relationship. A total of 61 experiments were conducted, involving 363 individual secondary drainages. Experiments covered a total of four different porous media, and three wetting phases. Results indicate that systems that exhibit greater resistance to flow (lower mean grain size and higher kinematic viscosity) also exhibit a greater sensitivity in to drainage rate. An imaging experiment was conducted to examine whether the source of the relationship could be observed through continuum-scale imaging. Results of the imaging were able to rule out membrane desaturation artifacts as a cause of the relationship, but were unable to identify significant differences in fluid configurations between fast and slow drainages that might lead to the observed effects.

• 出版日期2014-1