There have been various observations about the merits of increasing the proppant volume during hydraulic fracturing of source rocks. A general recommendation has been that larger proppant volumes can help in maintaining fracture flow capacity. In this study, we present data on actual cases related to more than 104 wells producing from the Bakken formation. Two parameters of interest were used as measures of well productivity. First was the average initial flow rate of the well, represented by the cumulative production during the first three months, and then was the production decline represented by the cumulative volume of oil produced in 180 days. Both of these parameters were tested as a function of corresponding sand/liquid ratios for similar completion practices and in the same reservoir. In all cases, we observed an an optimum value for the proppant liquid ratio related to the best case scenarios. Beyond that optimal ratio, the well performance show a deterioration. We attribute this to an overall reduction in fracture conductivity caused by packing of fractures, potential proppant plugging and slurry dehydration under excessive proppants placement.
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