One would imagine that in oil wet rocks, the scenario I sketched out for water wet rocks is simply magnified.

Initially, with oil wet rocks, the initial charge would be practically 100% oil - in effect single phase fluid flow yielding Kro = 1. Every pathway to oil flow no matter how tortuous has in effect negligible capillary pressure impediment to flow

As water floods the rock, the larger pathways become flooded with water, leaving the narrower (oil filled) pathways somewhat isolated, with oil emerging into the prevailing water flow paths needing to overcome capillary pressures to enter.