Influence of perforation shock-induced phase transformation on the collapsing strength of perforated casing

Collapse resistance property of oil and gas well casing is closely associated with material yield strength. Shaped charge jet perforating may induce phase transformation of the materials nearby, thus affecting the collapsing strength of perforated casing. First, by taking samples among the perforated P110 casings, the composition variation of samples in the proximity of perforation was observed using SEM. Second, a static tensile test was conducted on the test pieces with no perforations, machined perforations and jet perforations, so as to compare their performance variations under jet penetration. Finally, the influence of perforating shock-induced phase transformation zone on the casing's collapsing performance was analyzed by finite element simulation method. The study result suggests that shaped charge jet perforation will cause material composition variation and further affect the material's mechanical performance. Phase transformation can enhance the perforated casing's collapsing strength to a limited extent but significantly reduce its residual collapse strength.