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Indexed by:Journal Papers

Date of Publication:2020-04-01

Journal:INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL

Included Journals:EI、SCIE

Volume:95

ISSN No.:1750-5836

Key Words:Micromodel; CO2-brine displacement; Cross section; Saturation; CO2 storage

Abstract:CO2 sequestration into saline aquifers has been demonstrated as an effective technique to mitigate the effects of carbon dioxide on the atmosphere. The displacement mechanism during this process has not been clarified and the two-phase immiscible flow is affected by many factors. In this study, two types of homogeneous micromodels with circular and square cross sections were used to investigate the pore-scale of residual and capillary trapping at 25 degrees C and ambient pressure. Two salinities and six injection rates were used to study their impacts on CO2 saturation. Drainage experiments were conducted using a high-resolution microscope and a camera. The CO2 saturation and its distribution are investigated using image processing. Three forms of wetting phases are observed in circular grains, whereas additional special forms are observed in square grains, and these existing forms of the wetting phase are applied for mechanism analysis. Changes in the tortuosity and wettability are also analyzed to clarify why the saturation in the micromodel with square cross section was higher than that of circular cross section. The displacement pattern, the injection rate, the salinity, and the micromodel structure all have impacts on CO2 displacement efficiency and safe sequestration.