Zusammenfassung
Fractured carbonate reservoirs are principal crude oil and natural gas resources. These reservoirs are composed of matrix block with interconnected network of fractures. Oil or gas recovery from such low porous and low permeable reservoirs is important because a large amount of such hydrocarbon fluids are trapped inside those reservoir formulations. Water-flooding or more specifically spontaneous imbibition is one of the most effective recovery mechanisms to increase the production from fractured reservoirs. However, the performance of water-flooding mainly depends on the wettability of the reservoirs. In co-current imbibition, wetting phase displaces the non-wetting phase in such a way that the non-wetting phase moves in the same direction of the wetting phase. Hence the corresponding mathematical model requires a total flux condition. This study deals with the mathematical modeling of co-current spontaneous imbibition from heterogeneous porous reservoirs. The resulting governing equations are highly non-linear in nature. We solve these equations numerically and show that the co-current imbibition recovery is very much sensitive to the viscosity ratio, porosity variation models and the wettability of the reservoir. The impact of the viscosity ratio on the water saturation gradient and the end point mobility ratio is also analyzed. In addition, the variations in the heterogeneity and wettability of the medium and the corresponding influence on the sweeping efficiency of the co-current imbibition is investigated.
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