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"Propping Outside the Pay" is a hydraulic fracturing procedure used or applied on or to a vertical well. For applicable wells, it has the potential to enhance/increase fracture flow capacity and the resulting: (a) producing flow rate (b) total recoverable reserves and (c) monetary returns. It introduces an added aspect to optimizing treatment, i.e., proppant pile height above the pay. Hence "Propping Outside the Pay" is a double optimization approach, i.e., fracture penetration (Xƒ) and piled proppant height above the pay (Hƒp). The process creates more flow capacity from the pay to the wellbore through hydraulically created fractures that extend significantly outside the pay. It employs either one or both of the following: (a) injecting quantities of fracture propping material (proppant) that are greater than that normally used, and/or (b) creating more flow connections (e.g. perforations or open hole) from the wellbore to the propped fracture than are normally made. Additional proppant piled above the pay, and in the fracture below the pay (where proppant can settle) increases the fracture total cross sectional area and flow capacity. If the entire propped fracture is connected to the wellbore, the added fracture flow capacity enhances production rates over and above that predicted by the commonly used methods that are normalized on pay. At issue is economic viability, i.e., the additional proppant and perforating additional costs versus the monetary returns. Perforating costs are usually not significant as compared to first order proppant costs. Also, the applicable candidate wells require in-situ stress profiles such that the fracture will vertically propagate sufficiently above and/or below the pay to provide the opportunity to create additional fracture flow capacity. Experience indicates that a significant number of candidate wells exist. Computational studies showed that net present value returns from using the process can be significantly increased. The degree of increase depends upon the relative vertical fracture height to pay ratio, rock mechanics and reservoir parameters, hydrocarbon prices, fracturing costs, well spacing, etc. Examples comparing "Typical" cases to "Propping Outside the Pay" cases are shown. |
