Abstract
The flow of CO2 foam for mobility control in porous media is dictated by
the foam texture, or bubble density, which is commonly expressed as the
number of bubbles per unit of flowing gas. In most high-pressure
laboratory studies of foam in porous media, the local foam texture
cannot be determined due to opaque flow systems. Here, we unlock
real-time foam texture dynamics at high pressure (100 bar) by utilizing
a realistic pore network with an extended field of view. We identified
snap-off as the dominant foam generation mechanism, with additional
fining of foam texture caused by backward foam propagation. Foam
coalescence during continuous CO2 injection resulted in large gas
channels parallel to the general flow direction that reduced the overall
foam apparent viscosity. A large fraction of the CO2 foam remained
trapped (X_t > 0.97) and stationary in pores to divert CO2
flow and increase sweep efficiency. The gas mobility was calculated from
the fraction of trapped bubbles at the pore-scale, and the apparent foam
viscosity was in agreement with similar injection test performed at
core-scale. Hence, improved understanding of CO2 foam texture evolution
(n_f) can strengthen the validation of numerical foam models for
physical upscaling of flow phenomena, instrumental in the development of
field scale implementation of CO2 foam for in carbon utilization and
storage applications.