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The perforation impact dynamic loads can destroy or disable the tubing strings. The perforated completion process was simplified to explosion of ordinary explosive charge in perforation liquid. The dimensionless expression of perforation impact dynamic loads was derived based on main influence factors and then its engineering calculation formula was set up. A well perforation operation in western Sichuan as an example, the oil tubing strings security was analyzed by the perforation impact dynamic loads from the engineering computation formula. The results show that the tubing strings only occur elastic spiral bucking and do not occur plastic deformation which are in line with perforation operation results on site.

This paper presents a new energy approach based on the concept of a volume stain-energy-density factor useful to deal with the general problem of brittle fracture for sharp V-notches under mixed-mode I and II. The basic assumption is that the fracture occurs when the volume strain energy density factor arrive at its critical value in the direction of crack initiation where the deviator strain energy density factor is minimum. The method is validated taking into account experiment data already reported in the literature and the analytical predictions are in good agreement with experiment data. It indicates that the accuracy of the new approach is undoubtedly very satisfactory and can be applied in engineering.

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