Abstract: Adjustment of productive series with sands of low permeability not well-tapped on entering the stage of production with high water-cut is an important measure to stabilize production. The adjustment should be based on the character of sedimentation and morphology of sand bodies of the individual pay zones. In regrouping the productive series, the difference of permeability ratio should be taken into account. For pay zones deposited under weak fluvial action, the ratio of maximum permeability(Km)of a well over the permeability of a minor pay(Ki)of the same well should not be greater than 3, while for pay zones deposited under strong fluvial action, the ratio may not be greater than 5. Hydrophilic sands with air permeability of less than 300 and and oleophilic sands with permeability of greater than 300 and should not be grouped in the same productive series.