Effects of vertical permeability on oil production

For the case of zero vertical flow the layers are only equalised in pressure at the well-bores, and the flow in each layer is constant along its length. The 

When polymer has left the high-permeability layer, it should be noted that the case with a high degree of cross-flow is more effective in maintaining the incremental oil production in spite of the large quantities of polymer in the low-permeability layer. The reason is that the polymer in the low-permeability layer is largely concentrated near the injector and the cross-flow does not greatly influence flow from the production end. 

However, the cross-flow of oil accounts for only a small fraction of the total incremental oil production, so that the overall profile for kjk = 0.1 is similar to the case of kjk = 0.001. It appears that the vertical permeability has to be extremely low (k 0.001 kj in order to eliminate effectively the oil recovery mechanism. 

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