Liquid CO2 Displacement of Water in a Dual-Permeability Pore Network Micromodel

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• 作者：Changyong Zhang ; Mart Oostrom ; Jay W. Grate ; Thomas W. Wietsma ; Marvin G. Warner
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：September 1, 2011
• 年：2011
• 卷：45
• 期：17
• 页码：7581-7588
• 全文大小：976K
• 年卷期：v.45,no.17(September 1, 2011)
• ISSN：1520-5851

文摘

Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO₂ (LCO₂)鈥搘ater displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = 鈭?.1), unstable displacement occurred at all injection rates over 2 orders of magnitude. LCO₂ displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO₂ displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO₂ saturation (S_LCO2) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO₂ resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict S_LCO2 in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated S_LCO2.