Buoyancy-driven fluid migration in porous media

The slow upward migration, due to buoyancy, of a nonwetting fluid thorugh a saturated, three-dimensional porous medium has been studied experimentally, and by computer simulations. The height h of the invading fluid structure is proportional to the mass M of the invading fluid. The linear mass density S=M/h is found to scale with the dimensionless Bond number Bo (ratio of bouyancy and capillary forces) as S=A‖Bo${\mathrm{\Vert }}^{\mathrm{-}\mathrm{\alpha }}$, with α=0.72±0.06, consistent with theory and simulations. A noisy behavior in h(M) results from dynamical processes such as snapoffs and bursts.