Theoretical Investigation of the Effect of Membrane Properties of Nanoporous Reservoirs on the Phase Behavior of Confined Light Oil

摘要

This theoretical study is a first effort to probe the effect of semi-permeable membrane properties of nanopore networks on hydrocarbon phase behavior in tight-oil reservoirs. It is considered that the fluids stored in a nanoporous reservoir are divided into two parts: one part that is already “filtered” and can flow to a production well without compositional change, and another part that replenishes the “filtered” fluid according to the membrane efficiency of the nanopore network and the prevailing osmotic pressure. This selective hydrocarbon transport leads to a compositional change in both of the “filtered” and “unfiltered” parts, and changes other oil properties accordingly. The compositional change, fluid density, viscosity and interfacial tension are calculated as functions of pressure when the pressure decreases below the bubble point pressure of the “filtered” part. The findings of this work have ramifications on fluid saturation distributions and the composition of the trapped fluids in the beginning of a potential EOR application.