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High‐Speed Quantification of Pore‐Scale Multiphase Flow of Water and Supercritical CO 2 in 2‐D Heterogeneous Porous Micromodels: Flow Regimes and Interface Dynamics
Author(s) -
Li Yaofa,
Blois Gianluca,
Kazemifar Farzan,
Christensen Kenneth T.
Publication year - 2019
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2018wr024635
Subject(s) - saturation (graph theory) , porous medium , materials science , micromodel , permeability (electromagnetism) , multiphase flow , supercritical fluid , porosity , relative permeability , capillary action , viscous fingering , tortuosity , mechanics , capillary number , chemistry , thermodynamics , composite material , physics , mathematics , biochemistry , combinatorics , membrane
The pore‐scale flow of CO 2 and water in 2‐D heterogeneous porous micromodels over a C a range of nearly three orders of magnitude was explored experimentally. The porous geometry is a close reprint of real sandstone, and the experiments were performed under reservoir‐relevant conditions (i.e., 8 MPa and 21 °C), thus ensuring relevance to practical CO 2 operations. High‐speed fluorescent microscopy and image processing were employed to achieve temporally and spatially resolved data, providing a unique view of the dynamics underlying this multiphase flow scenario. Under conditions relevant to CO 2 sequestration, final CO 2 saturation was found to decrease and increase logarithmically with C a within the capillary and viscous‐fingering regimes, respectively, with a minimum occurring during regime crossover. Specific interfacial length generally scales linearly with CO 2 saturation, with higher slopes noted at high C a due to stronger viscous and inertial forces, as supported by direct pore‐scale observations. Statistical analysis of the interfacial movements revealed that pore‐scale events are controlled by their intrinsic dynamics at low Ca , but overrun by the bulk flow at high C a . During postfront flow, while permeability is typically correlated with total CO 2 saturation in the porous domain (regardless of its mobility), the saturation of active CO 2 pathways in the current study correlated very well with permeability. This alternate approach to characterize relative permeability could serve to mitigate hysteresis in relative permeability curves. Taken together, these results provide unique insights that address inconsistent observations in the literature and previously unanswered questions about the underlying flow dynamics of this important multiphase flow scenario.