某油井修复油管断裂原因分析

某油井在起甩管柱时第329根修复油管发生断裂。通过化学成分分析、力学性能测试、断口宏微观分析、金相检验以及受力分析等方法,对该油管的断裂原因进行了分析。结果表明:该油管为过载断裂,油管管壁因修复过程及均匀腐蚀减薄严重,使其承载能力大大降低,从而导致其在提升过程中的较大载荷作用下发生过载拉伸断裂。     

某气举井修复油管断裂原因分析

采用理化性能检验以及扫描电镜和能谱分析等方法,对塔里木油田某气举井修复油管的断裂原因进行了分析。结果表明:该修复油管的化学成分和力学性能符合相关标准对P110钢级油管的要求,油管断裂是由于油管内壁存在大量裂纹导致承载能力降低所致,而油管内壁裂纹的产生则是腐蚀疲劳和应力腐蚀开裂联合作用的结果。     

某油管短节断裂原因分析

某井在油管提升过程中,发现位于紧接油管挂下端的88.90mm×6.45mm油管短节发生断裂。通过宏观检验、化学成分分析、力学性能检测、显微组织分析、宏观和微观断口分析,对该油管短节的断裂原因进行了分析。结果表明:该油管短节为过载断裂,断裂的原因是油管短节外螺纹端的设计拉伸余量偏低,同时螺纹加工存在偏心,使油管短节的承载能力有一定程度的下降。     

N80-1钢加厚油管加厚部位断裂原因

在某油田下井作业时,一支N80-1钢加厚油管在加厚部位突然断裂。通过几何尺寸测量、宏观分析、力学性能试验、扫描电镜及能谱分析等方法,分析了该油管加厚部位断裂的原因。结果表明：油管加厚部位断裂为低应力脆断,主要原因是管坯铸造缺陷改变了油管内部应力状态和应力分布;加厚油管的拉伸性能和管体外径均不满足标准要求、加厚部位壁厚不均、管体轧疤缺陷和环状凹面是该加厚油管断裂的次要原因;在主、次要原因的共同作用下,使得油管在远低于额定最小破断拉力的重力作用下发生脆性断裂。     

某西部油田高温高压气井连续油管断裂原因

某西部油田高温高压气井连续油管在下井过程中发生断裂,采用宏观观察、无损探伤、化学成分分析、力学性能试验、金相检验、扫描电镜及能谱分析等方法,分析了连续油管断裂的原因.结果表明:该连续油管在下井过程中,管壁发生结腊,连续油管受到压缩载荷,导致下井受阻,当压缩载荷超过材料屈服强度后,连续油管发生压缩变形,随后发生断裂.     

N80油管断裂分析

采用化学成分分析、力学性能测试、受力分析、宏观及微观检验等手段对N80油管断裂的原因进行了分析。结果表明:该油管断裂的主要原因是在抽油机杆往复运动的过程中,管柱薄弱环节产生疲劳损伤,导致油管疲劳部位所承受的载荷超过了其承载能力,最终在外加拉应力的作用下发生断裂。     

某油井油管短节断裂原因分析

某油井生产11个月后发生油管短节断裂失效事故。通过对失效油管短节的宏观和微观形貌观察、显微组织分析、力学性能测试、化学成分分析,查明了其断裂失效原因。结果表明:该油管短节断裂主要是由于在油井生产工况下,油管内壁发生了多裂纹源的应力腐蚀开裂,然后在腐蚀和机械载荷的共同作用下,裂纹不断扩展并相互连接,当裂纹穿透管壁后表现为腐蚀疲劳开裂,最终导致油管短节断裂失效;油管短节加工工艺不当,提高了其断裂失效的概率。     

某井油管变扣短节断裂原因分析

某井油管变扣短节服役5个月即发生断裂失效。通过对失效油管变扣短节的宏观形貌、微观形貌、理化性能进行分析和检验,查明了其断裂原因。结果表明:该油管变扣短节断裂主要是由硫化氢应力腐蚀开裂导致的;由于该井硫化氢含量较高,因此建议该井油管柱采用抗硫材料。     

发动机燃油总管分油管断裂分析

采用外观检查、金相检验、断口宏观和微观分析,对发动机燃油总管分油管断裂的原因进行了分析。结果表明:分油管的断裂均为疲劳断裂,疲劳断裂位置一般位于管子接头的焊接区域,主要原因是该区域存在露出表面的焊接缺陷和装配应力过大。     

某油田用油管断裂失效分析

某油田直井气井在正常产气56d(天)后发生油管本体断裂失效。通过宏观检验、化学成分分析、力学性能测试、金相检验、扫描电镜及能谱分析,对该油管的失效原因进行了综合分析。结果表明:该油管的断裂性质属于腐蚀疲劳断裂;外表面脱碳降低了油管的耐腐蚀能力,在服役过程中管材外表面接触水及空气的位置发生氧腐蚀,形成腐蚀坑,腐蚀坑底部产生应力集中成为疲劳裂纹源;在外力作用下疲劳裂纹不断扩展,最终导致了油管的断裂失效。     

某稠油井Ф88．9mm×6．45mm110EU油管挤毁原因分析

对某井在稠油开采、反注稀油过程中发生的油管挤毁和断裂事故进行了调查研究。对挤毁油管和同批新油管取样进行材质分析、尺寸测量和挤毁试验,认为油管材质和尺寸均符合标准要求。对挤毁油管外表面形状检查结果表明,油管挤毁之前没有机械损伤,油管挤毁与机械损伤无关。通过推理分析,认为油管首先发生挤毁,然后才发生断裂。通过力学分析和计算,认为油管挤毁和断裂的原因是其所受的外力超过了油管的屈服强度。     

73．0mm EUJ55油管短节断裂原因分析

对断裂油管短节和新油管短节材质进行了对比试验,并对所用吊卡和油管接箍主要配合尺寸进行了测量和分析,发现吊卡磨损之后承载面孔径变大,油管接箍承载面本身偏小。根据尺寸测量结果,推断出了油管断裂时与吊卡的非正常配合状态。对油管断裂时的受力状态分析结果认为油管短节失效过程为：接箍一侧承载面滑入磨损的吊卡承载面内孔里边,管体倾斜与吊卡上活门体下端面内圆弧棱相撞产生裂纹和变形,最后在偏斜拉伸和冲击载荷共同作用下断裂。     

Investigation of stress corrosion cracking behavior of super 13Cr tubing by full-scale tubular goods corrosion test system

In this paper, a self-built device called “full-scale tubular goods corrosion test system” was used to test a 6 m length super 13Cr tubing (with coupling) to study its corrosion performance in spent acid. The specimen fractured at the tubing and was investigated by visual inspection, optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and mechanical test. It was the joint function of tensile force (78.6% actual yield strength), inner pressure (70 Mpa) and spent acid that induced stress corrosion cracking (SCC) of the tubing at 120 °C. Three different areas were found on the fracture surface, including crack initiation area, crack expansion area, and final fracture area. The fracture initiated from the “X” shape corrosion cracks which were evolved from small corrosion pits. The reduction of ductility and toughness may also facilitate SCC of the tubing.     

110钢级φ88.9mm×6.45mm超级13Cr钢油管刺穿失效分析

采用宏观分析、化学成分分析、力学性能测试、金相检验及扫描电镜断口分析等手段,对某油田一根规格为φ88.9mm×6.45mm的110钢级超级13Cr马氏体不锈钢油管的刺穿失效原因进行了分析。结果表明:油管失效的实质是油管发生了氯离子应力腐蚀开裂,裂纹起源于外壁腐蚀坑底部,从外壁向内壁扩展,直到穿透壁厚,形成刺穿通道,高压流体从内向外刺出并在随后的过程中形成了刺穿孔洞。     

Stress-corrosion cracking in copper refrigerant tubing

A metallurgical failure analysis was conducted to determine the cause of cracking in several sections of copper refrigeration tubing. The tubing in question was part of a new mechanical design, implemented to mitigate fatigue failures of solder joints that had occurred in tubing systems fabricated under the previous design. A comprehensive metallurgical evaluation revealed intergranular fracture of the copper in a region of the tubing that had been significantly cold worked during manufacture. On discovery of a source of moist ammonia in the system, associated with the location of failure, intergranular stress-corrosion cracking (SCC) was identified as the failure mechanism. A modified design, incorporating annealing of the formed copper tube section, was recommended to avoid future failures.     

Stresses in bent copper tubing: Application to fatigue and stress-corrosion cracking failure mechanisms

The residual and applied stresses in u-bent copper tubing are addressed in the context of both cyclic fatigue and stress-corrosion cracking. Failures as a result of fatigue and stress corrosion cracking in u-bent copper tubing have been observed to initiate at nonintuitive locations when only the applied stresses on the component are considered. This paper presents both qualitative classical and quantitative finite-element stress analysis results for the forming of u-bends. The resulting residual stress distributions are compared to fracture patterns generated by both fatigue and stress-corrosion cracking mechanisms.     

流量计导压管断裂失效分析

某化工厂工艺管线上的316不锈钢材质的孔板流量计导压管断裂,导致介质泄漏发生火灾。为查明其失效原因,对断裂的仪表管进行成分、硬度、金相、断口形貌和腐蚀产物分析,确认仪表管发生断裂的原因是在安装应力、震动和环境中Cl元素的共同作用下,先发生了应力腐蚀形成裂纹源,裂纹达到门槛值后又以疲劳形式扩展,最终导致开裂。     

油、套管脱扣、挤毁和破裂失效分析

通过调查研究和失效分析,列举了我国油田常见的油、套管脱扣、挤毁、破裂等失效形式,给出了每种失效形式的定义,对每种油、套管失效形式产生的原因及其影响因素进行了分析,并提出了具体预防措施。     

抗硫油管断裂原因分析

采用化学成分分析、断口分析、金相检验、扫描电镜分析等方法,对某油田抗硫油管的断裂原因进行了分析。结果表明：油管在硫化氢的腐蚀作用下,首先在管壁上产生局部腐蚀,继而在应力的作用下产生微裂纹并扩展,最终发生应力腐蚀断裂。最后,通过实验室模拟井况条件试验,提出了选择合适材料的建议。     

Analysis of Frequent Failure of Oil Well Tubings Due to Formation of Longitudinal Slit

In an onshore oil field, many premature tubing failures were observed in wells operating on sucker rod pump. Failures were in the form of longitudinal crack/vertical slit. During last three to four years, the failure frequency had increased and in one well, new tubing vertically cracked in 8 months only. In the internal surface of the tubing, a longitudinal grooving was observed. The shape of the groove resembled the sucker rod and the crack was along the groove. Observation of grooved region under SEM revealed abrasion features typical of mechanical wear. Small corrosion pits were also observed on some portion of grooved region. As the well was vertical, so chance of contact between tubing and sucker rod was low. But tubing was freely suspended in the well, i.e., there was no tubing anchor which made it vulnerable for the buckling. Analytical studies showed that the failed tubing was in buckling region. On comparison of hardness, it was observed that tubing material was softer than the sucker rod. Buckling of the tubing resulted in rubbing of sucker rod against tubing wall due to which tubing had worn out in the form of groove. Wear-oxidation and oxidation-wear of tubing surface at grooved region and corrosive agents of produced water accelerated this material removal process and when the wall thickness of the tubing at groove region reduced to a point where it was not enough to withstand the hoop stresses, a longitudinal crack formed in the grooved region and tubing failed.