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<p>A catastrophic longitudinal burst failure occurred in a P110 casing in an oilfield, which is investigated in this study as a typical industrial case. A systematic failure analysis was conducted through macroscopic examination, NDT, chemical and mechanical testing, metallography, EDS/XRD analysis, SEM fractography, and hydrostatic and burst tests to identify the root cause of the failure. The results reveal that deep mechanical surface scratches on the outer wall acted as stress concentrators, where microcracks initiated and propagated under repeated internal-pressure cycles (up to 57.89&#xa0;MPa over 44 cycles) during multistage fracturing. The accumulated damage finally led to a ductile low-cycle fatigue fracture and burst failure of the casing. The casing material was confirmed to meet relevant specifications, excluding metallurgical defects as the cause of failure. The failure is therefore attributed to installation-induced surface damage combined with cyclic internal-pressure loading. This case highlights the critical importance of protecting casing surfaces during installation and controlling pressure cycles in hydraulic fracturing operations.</p>

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Failure Analysis of a Ductile Low-Cycle Fatigue Burst of P110 Casing Induced by Mechanical Surface Scratches During Hydraulic Fracturing

  • 期刊论文

  • 发表日期：

    2026年5月21日

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  • Zenghai Wang,
  • Zhihao Yao,
  • Yisheng Meng,
  • Lang Ju,
  • Shengming Chen,
  • Bingyin Ji,
  • Jiaoqi Shi

摘要

A catastrophic longitudinal burst failure occurred in a P110 casing in an oilfield, which is investigated in this study as a typical industrial case. A systematic failure analysis was conducted through macroscopic examination, NDT, chemical and mechanical testing, metallography, EDS/XRD analysis, SEM fractography, and hydrostatic and burst tests to identify the root cause of the failure. The results reveal that deep mechanical surface scratches on the outer wall acted as stress concentrators, where microcracks initiated and propagated under repeated internal-pressure cycles (up to 57.89 MPa over 44 cycles) during multistage fracturing. The accumulated damage finally led to a ductile low-cycle fatigue fracture and burst failure of the casing. The casing material was confirmed to meet relevant specifications, excluding metallurgical defects as the cause of failure. The failure is therefore attributed to installation-induced surface damage combined with cyclic internal-pressure loading. This case highlights the critical importance of protecting casing surfaces during installation and controlling pressure cycles in hydraulic fracturing operations.