A water-wet vertical core plug initially saturated with oil is subjected to water injection from the bottom end, through a porous frit disc fully saturated with water and impermeable to oil. The core plug has a diameter of 1.0 inch and a length of 1.5 inch. Its absolute permeability and porosity values are 100 mD and 0.25, respectively. The residual water and oil saturations are Scw = 0.2 and Sor = 0.3, respectively; the initial water saturation of the plug is 0.22.
The system is at room temperature, and the density and viscosity values of the water and oil are ρw = 1.0 g/cc and ηw = 1.0 cP, and ρo = 0.85 g/cc and ηo = 3.0 cP, respectively.
The frit disc is 0.125 inch thick and has a permeability of 500 mD.
This two-dimensional model employs Cartesian coordinates.
The water saturation as function of the capillary pressure between the two liquids is given by a synthetic curve as shown in Figure 2. The relative permeability curves shown in Figure 3 are described by Corey relationships with Corey exponents of 5.0 and 2.5 for water and oil, respectively, while the end-point relative permeability values are krw_or = 0.25 and kro_cw = 0.7.
Gravity effects are included in the model.
Water injection occurs through the bottom boundary. The injection velocity is increased from zero at t = 0 to Vin = 13.2 micron/s in one minute, after which it is maintained constant (the value of Vin corresponds to an injection flow rate of five pore volumes per hour, for this two-dimensional geometry). The average water saturation Sw in the core plug as a function of time is plotted in Figure 4, while the distribution of Sw in the sample at selected time steps is shown through the Movie.