Spatial and Temporal Quantification of Spontaneous Imbibition

Abstract

Spontaneous imbibition—the process of a wetting fluid displacing a nonwetting fluid purely by capillary forces—is a ubiquitous phenomenon in porous and fibrous materials. Here we present a new experimental method for quantification of spontaneous imbibition in geologic materials. This method makes it possible to perform spontaneous imbibition under elevated pressure conditions relevant to environmental and energy resource applications. Computed tomography imaging reveals a new time‐independent scaling relationship that describes local imbibition rates as a function of water saturation. Imbibition capillary pressure curves are calculated with this wetting‐phase pressure and flow rate characterization, with no assumptions about the functional form, end point behavior, or scaling factors. Calculated end point capillary pressure is nonzero, in agreement with recent pore‐scale measurements of capillary pressure of trapped nonwetting phase. This work provides a new approach and insights into trapping and remobilization of nonwetting fluids in CO₂ storage reservoirs and contaminated groundwater aquifers.