Experimental study of crossover from capillary to viscous fingering for supercritical CO₂ - water displacement in a homogeneous pore network

Journal Article · Tue Jun 05 00:00:00 EDT 2012 · Environmental Science & Technology, 47(1):212-218

DOI:https://doi.org/10.1021/es3014503· OSTI ID:1060113

Wang, Ying ^[1]; Zhang, Changyong ^[2]; Wei, Ning ^[1]; Oostrom, Martinus ^[2]; Wietsma, Thomas W. ^[2]; Li, Xiaochun ^[1]; Bonneville, Alain ^[2]

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1. Chinese Academy of Sciences (CAS), Beijing (China)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Carbon sequestration in saline aquifers involves displacing resident brine from the pore space by supercritical CO₂ (scCO₂ ). The displacement process is considered unstable due to the unfavorable viscosity ratio (logM < 0). The unstable mechanisms that affect scCO₂ - water displacement under reservoir conditions (i.e., 41 °C, 9 MPa) were investigated in a homogeneous micromodel. A wide range of injection rates (logCa = -7.61~-4.73) was studied in two sets of experiments: discontinuous-rate injection, where the micromodel was first cleaned and saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate experiments, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa <= -6.61) and high injection rates (logCa >= -5.21), respectively. Crossover from capillary to viscous fingering was observed for logCa = -5.91~-5.21, resulting in a large decrease in scCO₂ saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during crossover from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (1988).1 Capillary fingering was the only mechanism that dominates all injection rates in the continuous-rate experiment, and resulted in monotonic increase in scCO₂ saturation.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1060113
• Report Number(s): PNNL-SA-87244; 39094; 45993; AA7020000
• Journal Information: Environmental Science & Technology, 47(1):212-218, Vol. 47, Issue 1; ISSN ‎0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory