Abstract
Oil zones in oil rim reservoirs are mostly in the transition zones; the region where relative permeability and capillary pressure are water saturation dependent, because of thin oil resource interval. These oil zones are with mobile water saturation, as oil production from rim reservoirs is characterized by early water production from water coning phenomenon. In this study, the influence of the capillary transition zone (CTZ) and reservoir wettability on water coning in oil rim reservoir were simulated using Black-oil Simulator ?? Eclipse-100. Capillary pressure ?? water saturation data were obtained from an oil rim reservoir in the Niger Delta. The different reservoir wettabilities; (water-wet, mixed-wet, and oil-wet), capillary pressure ?? saturation and relative permeabilities ?? saturation input data for the simulation were modelled based on Skaevenland et al. (2000) and Brooks and Corey (1966) correlations using multivariable numerical optimization approach. The simulation results from the integrated oil rim reservoir model indicated that the capillary transition zone (CTZ) increase water production and reduce oil recovery potential than non-capillary transition zone (NCTZ) in oil rim reservoir. Additionally, comparing the reservoir wettabilities showed that water-cut from water-wet was 0.961 and 0.733, mixed-wet 0.920 and 0.655, and oil-wet 0.920 and 0.631 for CTZ and NCTZ, respectively. This result showed that water-wet wettability for both CTZ and NCTZ in oil rim reservoir result in high water production than in mixed-wet and oil-wet wettabilities. Furthermore, cumulative oil production from water-wet was 1.425 MMstb and 1.640 MMstb, mixed-wet 1.770 MMstb and 2.036 MMstb, and oil-wet 1.757 MMstb and 1.985 MMstb for CTZ and NCTZ. Thus, the presence of CTZ; especially in water-wet reservoir influences the severity of water coning tendency in oil rim reservoir(s) than in mixed-wet and oil-wet reservoir wettability.
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