Unconventional wells require hydraulic fracturing to be economic. Several levers for improving well productivity are available including stage spacing, cluster spacing, and sand loading however much of the recent focus has been on perforation design as well as a more uniform distribution of sand and water. This paper proposes to evaluate how optimizing the perforation strategy might enhance stimulation distribution along the lateral, in the Marcellus shale.

Three different perforation designs were tested for better understanding of perforation efficiency, when considering design options such as perforation diameter, tapered perforating, and Extreme Limited Entry (XLE). A combination of step down tests, downhole perforation imaging and modeling are used to compare the different designs and support the conclusions.

Downhole ultrasonic perforation imaging, even if it only captures an end-of-job snapshot, provides valuable insight to the dynamics of limited entry perforating and sand distribution. The pre-fracture diameter is identified as a key uncertainty, while post-fracture measurements show variations from the specifications of the shape charge and, in some instances smaller perforation diameters when compared to the expected value. The current dataset allows for a better understanding on the concept of erosion and how to correlate erosion with actionable design parameters such as perforation diameter or rate per perf.

Downhole ultrasonic measurement of the perforation exit diameter, along with the corresponding erosion assumptions, are combined with modeling to recreate the rate and pressure evolution along the fracture stage., In addition, one can infer the actual volume of sand placed in each cluster in order to provide a quantitative assessment for future performance evaluation.

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