射孔冲击相变对射孔套管抗挤性能的影响

油气井套管抗挤毁性能与材料屈服强度关系紧密,聚能射流穿孔过程中可能诱发孔眼附近材料相变从而影响射孔套管抗挤强度。首先对射孔后的P110套管取样,通过扫描电镜观察孔眼附近样本组织成分是否发生变化;然后对无孔眼、机加孔眼和射孔孔眼试件进行静力拉伸试验,对比射流冲击影响下试件抗拉性能的变化;最后通过有限元仿真分析了射孔冲击相变区的存在对套管抗挤性能的影响。研究结果表明,聚能射孔会导致材料组织成分变化而影响材料机械性能;当相变对射孔套管抗挤强度起正向增强作用时幅度有限,起负向削弱作时用射孔套管剩余抗挤强度下降显著。

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.