1. n. [Enhanced Oil Recovery]

A laboratory test used to estimate the minimum miscibility pressure (MMP) or minimum miscibility concentration (MMC) of a given injection solvent and reservoir oil. The slim tube is a long coiled tube filled with sand of a specific mesh size or similar porous media. The tube is saturated at the beginning of each test with reservoir fluid at a given temperature. Solvent injection is performed at several test pressures. Effluent production, density and composition are measured as functions of the injected volume. Oil recovery after injection of a specific number of pore volumes (PV) such as 1.2 PV of solvent is the test criterion for miscibility. Two trend lines appear on a plot of recovery versus pore pressure for several slim-tube tests. The point of intersection of those trend lines is the estimated MMP for the given oil-solvent system. The data from a slim tube test can also be used as input to fine-tune a fluid equation of state for reservoir simulation.

See: minimum miscibility concentration,  minimum miscibility pressure,  rising-bubble apparatus