Abstract

To study capillary trapping phenomena in 2 and 3D a mathematical model is developed facilitating rapid fine grid computation of the saturation fields in heterogeneous reservoirs. The reduction in Computation time is achieved due to the fact that the model is much simpler than a conventional black oil simulator. Influence of wettability type, magnitude of capillary pressure, rate, and gravity forces are studied in 2D and 3D analytically (qualitatively) and by way of computations (quantitatively). It is shown that at infinite time in the strongly water wet reservoirs all the mobile oil is recovered, while in the oil-wet and mixed reservoirs a certain amount of capillary trapped oil exists. The capillary trapped oil saturation has a tendency to increase in the direction from injection to production wells, though it reveals a non-monotonous behavior locally.

The developed model is useful in calculation of recoverable reserves, and in optimization of waterflooding strategy to minimize remaining oil in heterogeneous reservoirs including the fractured ones.

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