Compositional Gravity Drainage Summary of Project Goals

The amount of wetting phase that is recovered by gravity drainage when the displacing fluid is not in chemical equilibrium with the initial fluid involves a complex interplay of gravitational, diffusive, and capillary forces. Recently, we have proposed analytic solutions for capillary/gravity equilibrium (CGE) in compositional gravity drainage, and using this solution estimated the total recovery of wetting phase for a two-phase three-component system. We also obtained experimental results suing an analog brine/isopropanol/iso-octane system (with non-parallel tie lines) in which the vertical profile of the components was measured destructively after 3 weeks of drainage. The condensing drainages compared favorably to the CGE solution and the vaporizing drainages to analytical solutions for advection dominated transport. Here I will present ongoing numerical simulations of compositional gravity drainage. We find that the CGE solutions are approached asymptotically as the simulation grid is refined for a simplified phase diagram. For vaporizing drainages, a bank of wetting fluid is found to be created from early times in the drainage through wetting fluid imbibing back into swept regions. We show that including hysteresis in the capillary pressure curve limits the creation of the wetting fluid bank. In future work, we plan to obtain experimental results for two-phase/4-component systems, which exhibit condensing/vaporizing behavior. This is planned to be compared to numerical simulations, which should give insight to analytic solutions.