Analytical model for detection the tilt in originally oil water contacts

Abstract EN

Many carbonate reservoirs in the world show a tilted in originally oil-water contact (OOWC) which is required a special consideration in selection the capillary pressure curves and an understanding of reservoir fluids distribution while initialization the reservoir simulation models.

An analytical model for predicting the capillary pressure across the interface that separates two immiscible fluids has been derived from reservoir pressure transient analysis.

The model reflects the entire interaction between the reservoir-aquifer fluids and rock properties measured under downhole reservoir conditions.

This model retains the natural coupling of oil reservoirs with the aquifer zone and treats them as an explicit-region composite system ; thus the exact solutions of diffusivity equation can be used explicitly for each region.

The reservoir-aquifer zones are linked by a capillary transition zone that reflects the pressure difference across the free water level.

The principle of superposition theorem has been applied to perform this link across the free water level to estimate the reflected aquifer pressure drop behavior that is holds the fluid contacts in their equilibrium positions.

The results of originally oil water contact positions generated by the proposed model have been compared with data obtained from a carbonate oil field, the results given by the model show full agreement with the actual field data.