Wellbore integrity during the full life cycle of a well has always been a focus of the petroleum industry, particularly during extreme drilling conditions and throughout complex well operations. Pumping compound fluids during hydraulic fracturing operations affects stresses on all tubular components, which can lead to component failure. During casing and tubing design, expected stresses are determined. This includes kick tolerance, drilling and production operations, and complete wellbore evacuation. However, a series of tubular failures indicates a more detailed analysis is necessary to help prevent well integrity loss.

This paper presents selected case studies of tubing failure during the hydraulic fracturing process. A transient program is used to determine the precise magnitude of stress on both the tubular and the connection. The analysis results are provided and discussed in detail. It is concluded that high localized dogleg severity and the sequence of fluids in the wellbore should be studied carefully because the stress on the tubing changes with the position of fluids and fluid density.

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