• Title/Summary/Keyword: Areal displacement efficiency

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Pore-scale Investigation on Displacement of Porewater by Supercritical CO2 Injection Using a Micromodel (초임계상 이산화탄소 주입으로 인한 공극수 대체에 관한 공극 규모의 마이크로모델 연구)

  • Park, Bogyeong;Lee, Minhee;Wang, Sookyun
    • Journal of Soil and Groundwater Environment
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    • v.21 no.3
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    • pp.35-48
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    • 2016
  • A micromodel was applied to estimate the effects of geological conditions and injection methods on displacement of resident porewater by injecting scCO2 in the pore scale. Binary images from image analysis were used to distinguish scCO2-filled-pores from other pore structure. CO2 flooding followed by porewater displacement, fingering migration, preferential flow and bypassing were observed during scCO2 injection experiments. Effects of pressure, temperature, salinity, flow rate, and injection methods on storage efficiency in micromodels were represented and examined in terms of areal displacement efficiency. The measurements revealed that the areal displacement efficiency at equilibrium decreases as the salinity increases, whereas it increases as the pressure and temperature increases. It may result from that the overburden pressure and porewater salinity can affect the CO2 solubility in water and the hydrophilicity of silica surfaces, while the neighboring temperature has a significant effect on viscosity of scCO2. Increased flow rate could create more preferential flow paths and decrease the areal displacement efficiency. Compared to the continuous injection of scCO2, the pulse-type injection reduced the probability for occurrence of fingering, subsequently preferential flow paths, and recorded higher areal displacement efficiency. More detailed explanation may need further studies based on closer experimental observations.

The Effect of Flow Rate on the Process of Immiscible Displacement in Porous Media (다공성 매체 내 비혼성 대체 과정에서 주입 유량이 거동 양상에 미치는 영향)

  • Park, Gyuryeong;Kim, Seon-ok;Lee, Minhee;Wang, Sookyun
    • Journal of Soil and Groundwater Environment
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    • v.23 no.1
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    • pp.1-13
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    • 2018
  • A series of experiments using transparent micromodels with an artificial pore network etched on glass plates was performed to investigate the effects of flow rate on the migration and distribution of resident wetting porewater (deionized water) and injecting non-wetting fluid (n-hexane). Multicolored images transformed from real RGB images were used to distinguish n-hexane from porewater and pore structure. Hexane flooding followed by immiscible displacement with porewater, migration through capillary fingering, preferential flow and bypassing were observed during injection experiments. The areal displacement efficiency increases as the injection of n-hexane continues until the equilibrium reaches. Experimental results showed that the areal displacement efficiency at equilibrium increases as the flow rate increases. Close observation reveals that preferential flowpaths through larger pore bodies and throats and clusters of entrapped porewater were frequently created at lower flow rate. At higher flow rate, randomly oriented forward and lateral flowpaths of n-hexane displaces more porewater at an efficiency close to stable displacement. It may resulted from that the pore pressure of n-hexane, at higher flow rate, increases fast enough to overcome capillary pressure acting on smaller pore throats as well larger ones. Experimental results in this study may provide fundamental information on migration and distribution of immiscible fluids in subsurface porous media.

The Effect of Temperature on the Process of Immiscible Displacement in Pore Network (공극 구조 내 비혼성 대체 과정에서 주입 온도가 유체 거동에 미치는 영향)

  • Park, Gyuryeong;Kim, Seon-ok;Lee, Minhee;Wang, Sookyun
    • Economic and Environmental Geology
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    • v.51 no.3
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    • pp.223-232
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    • 2018
  • The viscous force of fluids and the capillary force acting on the pore network of the porous media are important factors determining the immiscible displacement during geological $CO_2$ sequestration, these were directly affected by geological formation conditions and injection conditions. This study aimed to observe the migration and distribution of injected fluid and pore water, and quantitatively investigate displacement efficiency on various injection temperatures. This study aimed to perform micromodel experiments by applying n-hexane used as a proxy fluid for supercritical $CO_2$. In this study, immiscible displacement process from beginning of n-hexane injection to equilibrium of the distribution of the n-hexane and pore water was observed. The images from experiment were used to observe the displacement pattern and estimate the areal displacment efficiency of the n-hexane. For investigate the affects of the injection temperatures on the migration in macroscopic, migration of n-hexane in single pore was analyzed. The measurement revealed that the displacement efficiency at equilibrium state decreases as the temperature increases. The result from experiments indicate that the temperatures can affect the displacement pattern by changing the viscous forces and the capillary forces. The experimental results could provide important fundamental information on reservoir conditions and fluid injection conditions during geological $CO_2$ sequestration.