It is higher in smaller pores. That is why a fine-grained rock holds a taller saturation transition above the free-water level than a coarse sand does. Laboratory capillary-pressure curves, converted from the lab fluids to the reservoir fluids, give water saturation against height.
The same physics sets how tall a hydrocarbon column a seal can hold. The entry pressure of the seal rock is the capillary pressure needed to force hydrocarbons into it. Below that pressure the seal holds; above it, hydrocarbons enter the seal.