Fundamentals of Fluid Flow in Porous Media
Multi-phase Saturated Rock Properties:
Laboratory Measurement of Capillary Pressure: Mercury Injection
The mercury capillary pressure apparatus was developed to accelerate determination of the capillary pressure vs. saturation relationship. These tests can only be carried out on cleaned, dried test plugs. Mercury is normally a non-wetting fluid. The core sample inserted into a core chamber and evacuated (Figure 2‑58). The pressure in the system, effectively the differential across the mercury/vacuum interface, is raised in stages to force mercury enter to the core sample. The volume of mercury which has entered the pores at each pressure (as non-wetting phase saturation) is determined from volumetric readings, and the proportion of the pore space filled can be calculated. This procedure is continued until the core sample is filled with mercury or the injection pressure reach to some pre-determined value. These data gives the drainage curve. Further readings can be taken as the pressure is lowered to provide data for the imbibition case.