Pore-scale characterization of residual phase remobilization in geological CO2 storage using X-ray microtomography and pore-network modelling

• In this study, the pore-scale characteristics of trapped CO2 remobilization under pressure depletion conditions were studied with the use of 3D X-ray microtomography and pore-network modelling. Three-dimensional X-ray microtomographic images of a sandstone sample with a voxel size of 3.83 mm were acquired from which a pore network was extracted. Experimental results show that trapped CO2 remobilization during pressure depletion is an intermittent process in nature, due to which the CO2 relative permeability is significantly reduced. This serves as a safety enhancing feature as it delays CO2 remobilization and migration. Ostwald ripening plays a significant role in the CO2 phase redistribution, which could potentially lead to remobilization even in the absence of pressure depletion. According to the pore network simulation results, weakly wetting conditions enhances the reconnection of the trapped CO2 ganglia, which in turn promotes the remobilization of the trapped phase. The simulation and experimental results agree in terms of the saturation increment needed to remobilize the CO2 – approximately 0.06 – and the pressure at which the CO2 connects – around 7 MPa. The findings of the current study provide valuable insights into the pore-scale aspects of trapped phase remobilization, a phenomenon that affects the fate of CO2 residual trapping in both the short and long term. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Annan geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Other Earth and Related Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Multidisciplinär geovetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geosciences, Multidisciplinary (hsv//eng)

Nyckelord

Geological CO2 storage

Pore-scale

Residual trapping

Gas remobilization

X-ray microtomography

Pore-network modelling

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)