Compositional Gravity Drainage

David DiCarlo

In many reservoirs, gravity drainage is an effective recovery technique yielding very low residual oil saturations, with the total recovery depending on the ratio of the capillary force to the gravitational force.

For gas injection, the injected gas is never in chemical equilibrium with the oil in place which will lead to spatial variations in the interfacial tension and the amount of oil held by capillary forces. These types of capillary variations are also likely to occur in VAPEX displacements. We are currently using experiments, simulation, and analytic calculations to understand the complex roles capillarity, gravity, compositional changes, and diffusion play in these compositional gravity drainages.