Liquid Permeability Determination from Vacuum Imbibition in Tight/Shale Core Plugs

Liquid permeability is a key petrophysical parameterthat quantifiesthe ability of a liquid to flow through porous rock/soil and can beused in determining the efficiency of many subsurface processes, includingenhanced hydrocarbon recovery, groundwater transport, carbon dioxidegeostorage, underground hydrogen storage, etc. However, it is time-consuming(usually >16-240 h) and challenging to measure the liquidpermeabilityfor tight/shale rocks, particularly when the permeability is 100 nDor lower. The objective of this study is to develop a rapid and simpleapproach to determine liquid (brine or oil) permeability in tightsiltstones/shales. Specifically, the developed method is based onthe combination of one-dimensional (1D) vacuum imbibition experimentsin tight/shale core plugs and a modified Lucas-Washburn model.For our proof-of-concept study, the results have demonstrated that(1) only 44-116 h are required to determine the liquid permeability(98-608 nD) for the analyzed samples from the Montney and YanchangFormations; and (2) the acquired brine permeability was 28.3-28.5%lower than the slip-corrected nitrogen (N-2) permeabilityderived from the pulse-decay permeability tests. This is the firstattempt to determine the absolute permeability of a liquid accordingto a 1D vacuum imbibition experiment and theory. This study providesa promising technique for the fast characterization of ultratightformation permeability of around 100 nD.