Experimental investigation and evaluation of three-phase relative permeability models

Petroleum production often involves simultaneous flow of three immiscible fluids through underground porous rock formation. In this work, we measure two- and three-phase relative permeabilities with which we examine the performance of various 3-phase relative permeability models. The rock–fluid systems used in these measurements are comprised of sandstone samples, oil (n-decane), water (Nacl, 6000 ppm) and gas (nitrogen). The measurements were carried out at 23 ± 1 °C and 5.44 MPa. Two- and three-phase relative permeability measurements were obtained using the steady-state technique. The three-phase experiments were conducted such that the flow rates of brine and gas were increased gradually and oil rate was decreased to simulate the reservoir behavior during primary oil production. Several different flow rate ratios were selected so as to cover the saturation ternary diagram as completely as possible. The three-phase experimental results were compared with the prediction by different models which obtained by an in-house developed three-phase software. The results showed that in the primary imbibition case, the Blunt and Baker methods are more reliable than the other methods at low gas saturations.