It is known that the three important parameters, resistivity, capillary pressure, and relative permeability, are all a function of fluid saturation in a porous medium. This implies that there may be a correlation among the three parameters. There have been many papers on the approach to inferring relative permeability from capillary pressure data. However, the literature on the interrelationship between resistivity index, capillary pressure, and relative permeability has been few. The models representing such relationships have been proposed in this study, including a new model correlating relative permeability and capillary pressure. Some of the models were verified using experimental data for the first time. It has been shown that the other two parameters could be determined using these models if one of the three parameters (capillary pressure, relative permeability, and resistivity) is known. Using this approach, it would be possible to quickly obtain a distribution of capillary pressure and relative permeability characteristics as a function of depth and location across an entire reservoir.