| 摘要: |
| 通过对某失效高压气井超级13Cr油管的开裂原因、腐蚀形貌、腐蚀产物及有限元分析,探讨超级13Cr油管在高pH值完井液的腐蚀失效及应力腐蚀开裂(SCC)机制。结果表明:超级13Cr油管在高pH值完井液中发生应力腐蚀开裂,裂纹大多起源于油管外壁局部腐蚀坑处,其扩展方式由最初的穿晶解理开裂转变为沿晶开裂;超级13Cr油管外壁发生明显的腐蚀,腐蚀产物层厚度随井深增加显著增大,由外到内依次为Ca3(PO4)2沉积层、FeCr2O4高温氧化产物层及Fe3O4主要腐蚀产物层,其中Fe3O4腐蚀产物层出现较为明显的双向生长现象;超级13Cr油管在井下工况中的腐蚀机制为金属离子和氧离子在氧化膜和腐蚀产物膜中的反应扩散过程,其SCC开裂以阳极溶解机制为主,辅以膜致开裂机制,而疲劳载荷的存在促进了SCC裂纹的萌生和扩展。 |
| 关键词: 超级13Cr油管 高pH值完井液 腐蚀失效 腐蚀机制 SCC机制 |
| DOI：10.3969/j.issn.1673-5005.2020.01.016 |
| 分类号::TG 146.4 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目(51271146,51902254);陕西省自然科学基础研究计划项目(2016JM5064,2018JQ5108);西安石油大学《材料科学与工程》省级优势学科(YS37020203) |
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| Corrosion failure and SCC mechanism of super 13Cr tubings in high pH completion fluid |
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LÜ Xianghong1, ZHANG Ye1, XIE Junfeng2, XUE Yan3, WANG Chen1
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(1.School of Material Science and Engineering in Xi 'an Shiyou University, Xi 'an 710065, China;2.Petroleum Engineering Institute, PetroChina Tarim Oilfield Company, Kuerle 841000, China;3.Xi 'an Maurer Petroleum Engineering Laboratory, Company Limited, Xi 'an 710065, China)
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| Abstract: |
| Based on the cracking mechanism, corrosion morphology, corrosion products and finite element analysis of super 13Cr tubings in a failed high-pressure gas well, the corrosion failure and stress corrosion cracking (SCC) mechanisms of super 13Cr tubings in the high pH completion fluid were probed. The result shows that in the high pH completion fluid, the super 13Cr tubing has suffered from SCC, and most cracks originate from the local corrosion pits on the outer wall of the tubing. The crack growth transited from the transgranular cleavage-like cracking to the intergranular cracking.The outer wall of the super 13Cr tubing was significantly corroded, and the thickness of the corrosion product layer increases greatly with the increase of the well depth. The three layers are the Ca3(PO4)2 deposition product film, FeCr2O4 high-temperature oxidation product film and Fe3O4 main corrosion product film from the outside to the inside of the tube, where the Fe3O4 corrosion product film takes the phenomenon of bidirectional growth. The corrosion mechanism of super 13Cr tubings in the working environment is the reaction-diffusion process of metal ions and oxygen ions in the oxidation film and corrosion product film. The SCC mechanism is dominated by the anodic-dissolution, accompanied by the film-induced cleavage, and the existence of fatigue load promotes the initiation and growth of SCC cracks. |
| Key words: super 13Cr tubing high pH completion fluid corrosion failure corrosion mechanism SCC mechanism |
