The objective of this study is to assess the effects of capillary pressures and relative permeability hysteresis on the performance of wells using the downhole water sink (DWS) technology for water coning control.
In the study a commercial reservoir simulator has been adopted to evaluate well performance under conditions of stabilized oil production/water drainage rates for various combinations of these rates. Operational domain of water-free oil production, Inflow Performance Window (IPW), was used to quantify the effects of capillary pressure transition zone and relative permeability hysteresis on the water coning - control performance of DWS wells. Field data from wells in Canada, West Africa and Louisiana exhibiting severe problems of water coning were used in this study.
The simulation results show that the basic concept of the DWS is unchanged by the inclusion of capillary pressure and relative permeability hysteresis. However, these effects may cause considerable reduction in the size of the water-free oil production domain and lead to increase in water production.
The results also indicate that, for the same reservoir, converting conventional wells with prior water coning history to DWS application would not be as beneficial as DWS completions on new wells. Thus the effect of drainage-imbibition relative permeability hysteresis should be included in the DWS well design practice.