P110钢级油管接箍开裂失效分析

P110钢级油管应用于某井的试油作业过程中,短时间内发生了大量的接箍纵向开裂失效。通过宏微观分析、化学成分分析、力学性能试验、金相检验以及腐蚀产物分析等方法分析了该接箍开裂的原因。结果表明:开裂起源于接箍外表面,系油管材料在井筒内硝酸盐介质作用下于承受周向拉应力最大的接箍外表面处发生应力腐蚀开裂。     

某井110钢级油管失效原因分析

对某井110钢级油管进行检查时发现,油管和接箍台肩面结合处腐蚀严重,并且该油管端面发生严重变形。通过宏观分析、理化性能检测、X射线衍射(XRD)和X射线光电子能谱(XPS)等分析手段对该井油管失效原因进行了分析。结果表明:由于上扣扭矩过大造成油管端面发生弯曲变形;端面变形导致流经此处的流体的流态发生改变,对该部位形成冲蚀;油管和接箍相互挤压形成的压应力加剧了连接部位的CO_2腐蚀。     

L80油管螺纹接头腐蚀原因分析

某井L80油管下井投入使用仅6个月即发生螺纹接头腐蚀失效。采用宏观分析、金相分析、化学成分分析、腐蚀表面微观形貌及腐蚀产物分析等方法对现场发生腐蚀失效的管样进行了检验和分析;通过高温、高压工况模拟腐蚀试验,对油管材料的腐蚀行为进行了研究分析。结果表明:油管螺纹接头表面的腐蚀产物主要为FeCO3,腐蚀局部集中主要是由于油管在下井时,螺纹部位存在粘扣现象,从而导致螺纹接头的密封性能下降,高矿化度地层水及CO2等腐蚀介质渗入螺纹连接处,形成了缝隙腐蚀。     

某井超级13Cr钢特殊螺纹接头油管接箍横向开裂原因分析

对某井超级13Cr钢特殊螺纹接头油管接箍横向开裂事故进行了调查研究,对开裂油管接箍和未开裂油管取样进行了裂纹宏观分析、断口微观分析、化学成分分析、金相分析和力学性能试验。结果表明:接箍横向开裂导致油管特殊螺纹接头金属对金属密封结构失效,油管里的高压气体通过金属密封位置和接箍横向开裂位置发生泄漏;而油管接箍横向开裂与其存在原始裂纹和材料屈服强度偏高有关。     

某井油管接箍开裂原因分析

对某井在酸化压裂过程中油管接箍开裂导致的脱扣事故进行了调查研究,通过化学成分分析、力学性能试验、金相检验和断口微观分析等方法对开裂接箍进行了失效分析,同时对该批油管抽样进行了质量检查。结果表明:接箍开裂是由于其本身存在原始缺陷,原始缺陷在使用过程中扩展导致其开裂;抽检的其他油管质量合格。最后为了安全使用该批剩余的油管,防止类似事故的再次发生,提出了具体的预防措施。     

油管镀Ni-Fe-W合金层的耐疲劳和耐蚀性能

目前,不同腐蚀环境中油管选用Ni-Fe-W合金镀层时存在一定的盲目性。对QT-900油管电镀Ni-Fe-W合金,模拟某油田腐蚀环境,通过疲劳试验、高温高压腐蚀试验以及金相显微镜、SEM、EDS等分析手段,研究了Ni-Fe-W镀层对QT-900油管的耐疲劳及耐CO2酸性腐蚀的影响。结果表明:Ni-Fe-W合金镀层具有良好的耐CO2酸性腐蚀性能,其均匀腐蚀速率较低,且随CO2分压增加变化不大;Ni-Fe-W合金镀层显著提高了油管的疲劳寿命;疲劳失效的Ni-Fe-W合金镀层油管,裂纹均起源于表面镀层,贯穿镀层扩展至基体,刺口附近裂纹较为密集,距刺口350 mm处裂纹较为稀疏。     

P110E油管接箍应力腐蚀开裂失效分析

西部油田某井油管因接箍开裂而落井。通过宏观分析、理化性能检测、金相显微镜、扫描电镜(SEM)、能谱仪、X射线衍射仪(XRD)等对该井开裂接箍进行了失效分析。结果表明:接箍开裂属于硫化物应力腐蚀开裂,该井硫化氢含量较高是接箍开裂的主要原因,此接箍材料不适宜在含硫环境下使用。     

φ127mmS135钻杆刺漏失效分析

采用宏观分析、化学成分分析、金相检验、断口分析和力学性能检测等方法并结合钻杆的受力和环境工况对φ127mmS135钻杆管体发生刺漏失效的原因进行了分析。结果表明：钻杆的刺漏失效形式为腐蚀疲劳失效;钻杆外表面存在腐蚀坑,在交变应力的恶劣工况作用下于腐蚀坑底部萌生疲劳裂纹并扩展,最终发生刺漏失效。     

某井特殊螺纹接头油管脱扣原因分析

对某井特殊螺纹接头油管脱扣事故进行了深入调查研究,对失效油管试样进行了宏观分析、几何尺寸测量、金相分析、力学性能试验和化学成分分析;对油管在井下的受力状态进行了分析,对油管脱扣和接箍开裂的先后顺序进行了推断。结果表明:油管接箍脆性开裂导致了油管脱扣事故,油管接箍开裂主要与其材料屈服强度、硬度偏高以及修井过程中油管所受的温度载荷有关。     

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。     

P110油管腐蚀穿孔分析

通过化学成分分析、金相检验和腐蚀产物分析等方法对P110油管腐蚀穿孔的原因进行了分析。结果表明:CO2腐蚀是造成油管腐蚀穿孔失效的主要原因。     

酸性油气田C110套管断裂失效分析

为查明酸性油气田某油井C110套管断裂失效原因,通过C110断裂失效套管断口宏观形貌、金相组织、化学成分、力学性能和腐蚀产物成分等综合分析,对酸性油气田某油井C110套管断裂原因进行了探讨。结果表明:套管不居中导致套管产生应力集中,并在套管与卡瓦咬合的第1个齿形成严重机械损伤;同时,地层运动、套压波动等因素导致套管在应力集中部位出现交变载荷。最终,在套管内壁处于高H2S、低p H值环境下,在内表面交变应力集中区域发生腐蚀疲劳开裂。     

液压万能试验机油管接头漏油改造实践

通过分析确认液压万能试验机油管接头漏油的原因是电磁换向阀工作时产生的振动使油管接头根部产生横向裂纹,据此制定了两套油管改造方案：一是增加钢质油管接头的壁厚,提高接头的耐振动疲劳性能;二是用高压钢丝编织胶软管替代钢质油管,由钢性连接变为柔性连接,减小振动的传递。实际运行结果表明：改造后试验机运行状况良好,未再出现漏油故障,从而有效地保证了试验机的正常运行,且避免了油料的浪费和环境的污染。     

某输油管道腐蚀穿孔原因

某油田在巡线过程中发现输油管道有泄漏现象,通过宏观分析、化学成分分析、金相检验和腐蚀产物分析等方法,结合服役工况,对输油管道腐蚀穿孔的原因进行了分析。结果表明:环焊缝防腐补口的密封失效而导致的外层腐蚀是输油管道腐蚀穿孔的主要原因,同时土壤中的Cl^-加速了腐蚀穿孔的发生。     

Failure mechanism of sucker rod coupling

Failure of sucker rod coupling or tubing is a major problem in sucker rod pumping systems, which occurs constantly in oil fields around the world. Such failures can lead to heavy maintenance work and higher expenses in oil production. To date, no economical method has yet been proposed to address the problem. In this paper, three samples with different service times are selected from California oil fields and are analyzed in details. A comparison of the dimensions and macro-morphologies of the samples with different service times is used to reveal the failure process. Failure mechanism is discussed based on the analysis of the micro-morphologies, microhardness, microstructures, and chemical composition of the samples. The analytical results indicate that the damage is initially caused by abrasion between the coupling and the tubing; the contact load decreases as the coupling diameter decreases, and the synergistic action between wear and corrosion becomes the main damage cause. Large numbers of defects (pores) in the material can accelerate both corrosion and wear aspects of the damage. Alternating stress may affect the mechanical properties of the coupling, but it is not the main factor of failure.     

P110石油套管水压试验开裂原因分析

通过对材料的化学成分分析、断口分析及金相检验,对φ177.8 mm×11.51 mm P110石油套管水压试验后出现的管体异常开裂现象进行分析。结果表明:导致管体纵向开裂的原因是该套管管体组织内分布着大型夹杂物,它的存在破坏了材料组织的连续性,削弱了横向抗拉强度,在应力集中的条件下,局部应力超过实际的抗拉强度从而产生开裂。     

基于三叶扭曲膨胀管技术的油冷器实验分析

传统管壳式油冷却器的传热效率较低,且存在壳程流动死区及易结垢等缺点。本文采用新型三叶形扭曲膨胀管技术提高传统油冷器的传热。通过实验测试平台测试得到的三叶形扭曲膨胀管油冷器传热及压降数据,与光滑圆管油冷器、传统翅片管油冷器和花瓣状翅片管油冷器进行对比分析。研究结果表明,采用三叶形扭曲膨胀管技术能明显提高油冷器传热系数,但比外翅片管油冷器压降更高,在较低雷诺数下,三叶形扭曲膨胀管油冷器综合性能比翅片管油冷器差,而随雷诺数增加,其综合性能逐渐优于外翅片管油冷器,具有很好的推广应用前景。     

油气管线热电偶套管断裂原因分析

某炼油厂油气管线上的一个热电偶套管发生断裂,使用时间仅6个月。对断裂套管进行了断口形貌、材质成分、金相组织等分析。结果表明,套管断裂主要原因是管线中油气流的冲击和湍流作用,引起套管的共振．进而产生疲劳断裂。     

Erosion Corrosion on Oil Coolers for Navy Ships

Incorrect material selection does not always lead to corrosion. In addition to an inferior selection of materials, unsuitable operating conditions and poor design also contributed to the presented failure. A combination of erosion and corrosion caused a leak in an oil cooler of a Navy ship. Because there was no welding seam between the deflectors and tube plate on the carbon steel cooler, cooling water could stream between them, and the flow rate became excessive. This caused erosion on the tube plate. In addition, the repeated change of the cooling liquid after servicing caused a uniform corrosion attack.     

Numerical modeling of multi-stage tube hydropiercing

Hydropiercing is a cost-effective method for piercing holes in a hydroformed tubular structure. When the tube wall around a pierced hole is also extruded toward the inside of the tube, brackets or other connecting parts can be fastened to the hydroformed structure by inserting a self-tapping screw into the extruded hole. In this study, three-dimensional finite element simulations of the hydroforming, hydropiercing and wall extrusion of a DP600 steel tube were performed using different damage criteria. The constant equivalent plastic strain, with and without cut-off stress-triaxiality values (CEPS+C and CEPS, respectively) and the Johnson–Cook (JC) damage criterion were considered as phenomenological damage models, and the Gurson–Tvergaard–Needleman (GTN) criterion was used as a micro-mechanical damage model. In order to calibrate the parameters in each model, tube-piercing tests were conducted and the punch load versus displacement response was determined. The damage parameters were then calibrated by correlating the predicted punch load versus displacement behavior to the experimental data, considering particularly the load reduction behavior when the slug breaks through. The calibrated damage parameters were then used in simulations of the multi-stage hydropiercing and tube-wall extrusion process and the accuracy of each damage criterion was evaluated in terms of the predicted deformation and damage behavior. The damage accumulation direction during the hydropiercing, depth of roll-over, and tube extruded length were the main parameters in the evaluation of each damage criteria. JC and CEPS+C criteria showed the best agreement with the experimental observations.