Capillarity and phase-mobility of a hydrocarbon gas–liquid system

When oil fields fall during their lifetime below the bubble point gas comes out of solution. The key questions are at which saturation becomes mobile (“critical saturation”) and what mobility is, because reduces production significantly. traditional view is that phase once bubbles grow or expand to a size where they connect form percolating path. For typical 3D porous media corresponding this percolation limit on order 20%. However, significant literature report lower limits thresholds i.e. 0.1%. A direct experimental insight for lacking laboratory measurements notoriously difficult since formation includes thermodynamic kinetic aspects, pressure decline rates achievable in experiments orders magnitude higher than field. Here we study nucleation transport coming solution in-situ rock using X-ray computed micro tomography allows visualization kinetics connectivity gas. We use either propane propane–decane mixture as model system conduct depletion absence flow finding – consistent with observation medium decreased rate dependent kinetics. That occurs single-component systems hydrocarbon mixtures. Pressure results critical saturations between 20 30% structures. does not explain experimentally observed significantly Also, respective pore level fluid occupancy pores filled liquid but partially both normal 2-phase immiscible rather diminishes phases. This indicates likely other mechanisms play role establishing Experiments under conditions, injected near suggest diffusion may contribute even be dominant mechanism field relevant rates. consequence diffusive compositional gradients locally composition such occur. would lead disconnected distribution ahead convective front. Furthermore, exchange leads ripening anti-ripening effects influences see evidence so much low injection. Respective relative permeability from imaged distributions lattice Boltzmann approach show distinctly different behavior flowing conditions. These findings capillarity gas–liquid far more complex system. Capillarity coupled thermodynamics fast time scale diffusion-dominated slow scale. While consequences current modelling approaches yet fully clear, shows research needed understand these implications.