The water film formed within the pores of tight reservoirs leads to a distinct "oil?core water?film" configuration in the distribution of oil and water within the porous medium, which has a significant impact on the flow channels and capillary forces of infiltration and absorption. To address these phenomena, high?pressure mercury injection and core imbibition experiments were conducted to study the microscopic distribution characteristics of oil?water and the underlying mechanisms of capillary forces. A capillary force calculation model considering water film thickness was established to elucidate the influence of water content distribution on capillary force. The results indicate that as the oil phase pressure increases, the water film on the pore wall gradually becomes thinner until it stabilizes. Under the same pressure, the smaller the pore size, the larger the proportion of water film to the pore size. When the capillary radius is less than 30 nm, the smaller the radius, the greater the influence of water film on capillary force; when the capillary radius is greater than 30 nm and the water saturation is greater than 0.60, the capillary force calculated with and without considering the water film is basically equal, and the influence of the water film on the water saturation and capillary pressure is relatively small. When the water saturation is less than 0.60, there is a significant difference in capillary force between the two conditions. Higher water saturation corresponds to a smaller deviation in capillary pressure. Furthermore, lower capillary forces are associated with reduced imbibition capacity and permeability of the rock core.