High initial water saturation exists in some petroleum reservoirs. Initial water movement has impact on reservoir simulation and the impact is investigated. An experiment method is developed to measure water effective permeability under initial water saturation. Simulation and modeling are performed to study its effects on initial water movement in a reservoir.

There are several results based on the experiment and simulation results. Initial water movement can occur and its effective permeability is measurable. The effective permeability of the continuous water network is small and in the scale of milli-Darcy. Initial water movement can change pressure profile and simulation results.