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Pore level fluid occupancy for a single component system (A, B) and a two-component system (C–F). In the single-component case, above the bubble point the whole pore space is filled with liquid while below the bubble point pressure (A), after equilibration, the whole pore space in the field of view is filled with gas (B). In the two-component system, that behavior is distinctly different. In pressure-depletion experiments, below the bubble point pressure pores are either filled with liquid or with gas (C–F). There are no partially occupied pores like in normal water–oil displacement experiments (see e.g. Fig. 4 in  or Fig. 3 in ).