For waterflooding oilfields, both the lab experiments and field practices have proved that the physical properties of water-flooding reservoirs would be altered due to the washing of injected water. This condition has not aroused enough attention. There is no proper approaches to describe the change of reservoir parameters against water flux in reservoir simulation. Most commonly used reservoir simulators (Eclipse, CMG, et al.) neglect the alteration of reservoir properties during simulation, and thus, lead to unreasonable history matching and production forecasting.

A new parameter known as Pore Cross-sectional Area Flux (PCAF) is introduced to continuously characterize the time-variation of a property during simulation. This new method overcomes the disadvantage of the previous characterization approach known as Pore Volume (PV), which is strongly dependent on grid size.

A new numerical simulation software in which reservoir properties are considered functions of PCAF is developed based on the black oil model, and the new simulator is validated against Eclipse. Furthermore, the effects of the time-variation of different parameters on the ultimate oil recovery are investigated. Finally, this simulator is applied to SZ-I oilfield in Bohai Bay to demonstrate how this simulator can achieve more accurate simulation.

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