Pore-scale two-phase ﬁltration in imbibition process through porous media at high- and low-interfacial tension ﬂow conditions
This study provides new insights into pore-scale two-phase ﬁltration during imbibition process through porous media under the high- and low-interfacial tension (IFT) ﬂow conditions. First, the distribution and conﬁguration of imbibing wetting and non-wetting phases in primary imbibition (free spontaneous imbibition or wetting process) is depicted. Second, the detailed pore-scale topology, structure, distribution, and conﬁguration of different phases together with the pore-scale displacement mechanisms in primary drainage (i.e., desaturation of continuous wetting phase or de-wetting process), secondary imbibition (i.e., controlled spontaneous imbibition or desaturation of continuous non-wetting phase in high-IFT ﬂow condition), and tertiary imbibition (i.e., forced imbibition or mobilization of discontinuous trapped nonwetting phase in low-IFT ﬂow condition), are expounded. Finally, the advance of the displacement front and ﬂow pattern conﬁguration in secondary and tertiary imbibition is demonstrated and discussed. Furthermore, in tertiary imbibition, the blob size distribution of the displacing wetting phase, formation of the secondary displacement front and wetting ﬁlm before breakthrough of the displacing wetting phase, rate-dependency of the advance of secondary displacement front and wetting ﬁlm, interruption of the wetting ﬁlm ﬂow within wetting ﬁlm region, pore-level phenomena within the wetting ﬁlm region, and role of wetting ﬁlm in pore-scale displacement mechanism are elucidated.