When frac packing as a completion technique, long treating intervals or heterogeneous lithology within the intervals being treated have led to the use of various methods, equipment, and techniques for ensuring the complete treatment of the intervals. Shunt tubes attached to sand screens can provide an alternate path for fracpack slurry to flow past a bridge if it were to form in the borehole-screen annulus. A concentric annulus packing system using a specific design of perforated liner around the sand screens has also been used to successfully fracpack producing intervals that were thought to have a high risk of forming a bridge inside the borehole before all parts of the interval were properly treated (Lemesnager et al. 2008).

Though using these technologies has led to successful completions, it is less clear how to determine when the fracpack enhancing technologies are actually required. The use of any of the enhancing technologies will likely require some compromise to the flow area (reduction to inner diameter), complexity in installation, or risk to potential retrieval, and at least adds to the cost of the completion. Thus, some means of analyzing when the technologies are required is desirable. A new treatment design analysis software tool has been developed for estimating the amount of liquid leak-off which will occur to a screened-out fracture and corresponding annular bridge if such were to form in the upper (or upstream in the case of high deviation or horizontal wells) portion of a long-treating interval. By determining the amount of liquid leak-off from the slurry being pumped during a fracpack to a bridged-off fracture, a better estimation of the likelihood of successfully packing or fracpacking the remaining portion(s) of the interval with the resulting slurry can be made. Alternatively, by estimating the leak-off in advance with this design tool, we can modify the slurry design to account for the anticipated liquid loss (e.g., by increasing the ratio of liquid to proppant), thus enhancing the likelihood of success. With this new analysis tool, more reliable decisions can be made about the need for treatment-enhancing alternate path or concentric path screens.

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