Failure analysis of IEU drill pipe wash out

Many 127.0×9.19 mm IEU G105 drill pipe failures of wash out occurred after 2367 h of pure drilling time and 8726 m of penetration footage. This paper gives a detailed investigation on these failures and a systematic analysis is carried out on service and loading conditions of the drill pipes. Measurement and inspection were performed on configuration dimensions, chemical composition, mechanical performance, metallography, macro-fractography, micro-fractography, and corrosion products. Configuration stresses at the crack positions of the drill pipe were calculated by FEA. Crack extending velocity of the drill pipe material under corrosion medium was also measured. It is thought from test and analysis results that the drill pipe wash out or fracture accidents were premature corrosion fatigue failure accident. The failure courses were as the following: corrosion pits occurred first on the internal surface at the stress concentrating area of the drill pipe, and then fatigue cracks initiated in pit bottoms, and washed out or fractured subsequently as cracks penetrated through the wall thickness of the drill pipe. The reasons of drill pipe wash out were related to configuration, material quality, and load condition of the drill pipe string.     

DZ55钢级Ф102mm×9.19mm地质钻杆管体断裂原因分析

通过宏观分析、金相检验、化学成分分析、力学性能测试和扫描电镜微观分析对一DZ55钢级Ф102mm×9.19mm地质钻杆的断裂原因进行了分析。结果表明：因该地质钻杆管体外壁存在较多的螺旋状划痕和刮蹭痕迹造成应力集中,加之钻杆材料韧性较低,从而导致钻杆管体在钻进过程中于损伤处萌生裂纹,裂纹不断扩展最终发生脆性断裂。     

Investigation into the Cracking of SAILMA 350 HI During Forming

Vanadium microalloyed hot rolled steel of 13.8 mm thickness, when hot formed at 900 °C into axle housings were rejected because of a prominent crack running along the length of the component. A detailed metallurgical investigation revealed that the cracking during forming was the result of the opening up of pre-existing fine crack along the length of the hot rolled coils. These cracks were barely visible on the hot rolled coils that were formed into the axle housings. Metallographic and hardness tests indicated that these cracks might have been generated as a result of decarburization of the slab during soaking that led to a softer surface layer of the slab. During subsequent hot rolling mechanical defect might have been caused on the decarburized surface that is much softer than a material with a usual carbon content. It was concluded that soaking in the reheating furnace with low carbon potential might have led to extensive decarburization of the slabs. Soaking in a furnace atmosphere with adequate carbon potential was recommended as a remedial measure to prevent decarburization of the surface layers of the slabs.     

42MnM07地质钻杆断裂原因分析

通过化学成分分析、断口分析、金相检验和扫描电镜观察等方法,对42MnMo7铜地质钻杆的断裂原因进行了分析。结果表明：钻杆在交变力作用下,在螺纹根部的应力集中处产生裂纹．此裂纹在过载力和钻杆基体存在带状脆性马氏体的情况下进一步扩展,最终导致钻杆发生断裂。最后对此提出了相应的措施及建议。     

G105钻杆管体刺穿失效分析

某油田钻井公司使用的规格为φ101.6 mm×8.38 mm的G105钻杆先后发生两起管体刺穿失效事故,通过化学成分分析、力学性能测试、金相检验、X射线衍射等方法并结合钻杆的受力状态对钻杆刺穿原因进行了分析。结果表明:钻杆刺穿失效形式为腐蚀疲劳,在钻井液中腐蚀介质作用下,钻杆首先发生氧腐蚀和Cl~-加速腐蚀,使钻杆外表面产生许多腐蚀坑,并于腐蚀坑底部形成应力集中;随后在钻井过程的交变应力作用下,应力集中严重的腐蚀坑底部开始萌生裂纹,裂纹不断疲劳扩展直至穿透管壁;最终在钻杆内钻井液的冲刷作用下发生刺穿失效。     

5-1/2FH双台肩钻杆内螺纹接头断裂原因分析

采用宏观检验、化学成分分析、力学性能测试、金相检验和断口分析等方法对某5-1/2FH双台肩钻杆内螺纹接头的断裂原因进行了分析。结果表明:此双台肩钻杆内螺纹接头在副台肩第一完整螺纹根部发生了疲劳断裂失效。断裂具有多源特征,起源于内螺纹根部并向外壁扩展,当穿透壁厚形成通道时发生了刺漏,从而使断口表面形成了冲刷痕迹。上扣扭矩不足,同时接头承受的弯曲应力较大是造成接头疲劳断裂失效的主要原因,另外FH型螺纹固有的螺纹根部半径较小、应力集中较大,使接头失效的风险增大。     

钻杆接头台肩根部刺漏失效分析

通过力学性能测试、化学成分分析、金相检验和断口分析等方法对某井发生的钻杆接头台肩根部刺漏失效原因进行了分析。结果表明：材料冲击功低于标准要求,接头台肩根部受到严重腐蚀,形成大而深的腐蚀坑,在交变应力作用下,裂纹萌生于腐蚀坑底部,并迅速扩展,最终导致钻杆接头发生早期腐蚀疲劳失效。     

φ139.7 mm×10.54 mm G105钻杆刺穿失效分析

采用宏观分析、化学成分分析、力学性能试验、金相检验、扫描电镜断口分析及能谱分析等手段对某规格为φ139.7 mm×10.54 mm的G105钻杆的刺穿原因进行了分析。结果表明:钻杆刺穿的实质是早期疲劳失效;蹩钻、跳钻等钻柱振动引起钻杆上产生的严重交变应力是导致钻杆失效的主要原因;钻井液中的溶解氧对钻杆外表面造成氧腐蚀并形成腐蚀坑,促进了疲劳裂纹的萌生;钻铤直接过渡到钻杆,截面变化突然,使应力集中加剧,也是导致钻杆发生疲劳失效的原因之一。建议在钻井液中添加除氧剂和缓蚀剂,并适当降低钻压,调整钻井参数,避免钻柱剧烈振动。     

Failure analysis of drill pipe: A review

Although the drill pipe is a simple tool in the drilling industry, it is the most used and important one. The drillstring failure has two general forms: wash-out and twist-off. These failures begin with mechanical, thermal and corrosion fatigue cracks. On the basis of previously conducted researches, the failure of drillstring is not unknown. However, the occurrence of drillstring failure still is too much. The main reason for this can be due to complex loading, combined stresses and different types of vibrations and moreover, the corrosive and erosive behavior of drilling mud that makes the total condition of the well so difficult to analyze. In this paper, the attention is focused on the analysis of drill pipe failure and the fatigue crack is represented for the root cause of drill pipe failure. The aims of most of published papers are to examine how and why a specific drill pipe is failed and just the main reason of failure for that drill pipe is discussed in detail. In this paper all metallurgical and mechanical aspects of failure that can occur for a drill pipe, are considered and discussed. And finally, this comprehensive review leads to a conclusion that categorizes the primary sources of drill pipe failure into seven major groups and makes some recommendations to avoid them.     

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。     

钻杆疲劳寿命预测技术的研究现状与展望

钻杆是石油天然气钻井的最主要工具,也是失效最为频繁的钻井工具。钻杆的失效绝大多数与疲劳有关,钻杆疲劳寿命预测技术的研究对于控制钻杆失效事故的发生具有重要意义。综述了当前国内外在钻杆疲劳寿命预测技术方面的研究现状及取得的研究成果,针对各种钻杆疲劳寿命预测方法的特点及应用情况进行了详细介绍,并分析了钻杆疲劳寿命预测过程中面临的问题。最后,展望了钻杆疲劳预测技术研究的重点方向和发展前景。     

钻柱扭转和纵向振动的等效网络分析

忽略阻尼对钻柱振动的影响,在一维钻杆扭转振动和纵向振动方程的基础上,推导出单根钻杆和多根相同钻杆扭转振动和纵向振动的等效网络.利用等效网络级联理论,结合钻柱系统边界条件,给出了钻柱扭转振动和纵向振动的等效网络和机械等效阻抗表达式,阐述了根据机械等效阻抗确定钻柱扭转振动和纵向振动机械共振频率的原理和方法.由等效网络分析法...     

Optimization Analysis on the Effects of Slip Insert Design on Drill Pipe Damage

New oil and gas reservoir discoveries in deep conditions have become common. Constructing wells in these deep environments has challenged the petroleum industry to develop new technologies for reaching extended depths while focusing on limitations of the pipes due to excessive damage from slips. This paper addresses a serious problem pertinent to the design of slip insert. Firstly, a series of numerical simulation models are established to analyze the effects of slip insert design on drill pipe damage under a pipe weight of 200 tons, where the drill pipe is 5 in. which is subjected to the American Petroleum Institute. Secondly, the models are conducted to find the optimized parameters of the slip insert by comparing the maximum stress of different combinations. Finally, laboratory experiment is carried out to verify the simulation results. For the drill pipe and slip system selected, an optimized slip insert with a front-rake angle of 75°, a back-rake angle of 30°, a chamfer of 0.2 mm, and a tooth height of 2 mm is obtained. This research provides a method for designing the slip insert.     

Failure analysis and appropriate design of drill pipe upset transition area

In recent years, the drill pipe failures often happen in the case of ultra deep well drilling and complex geological conditions drilling. One of the main failure types is the stress concentration at the upset transition area of the drill pipe. Based on the elastic–plastic mechanics, finite element theory, and application of numerical simulation analysis for the actual mechanical properties of three-dimensional simulation analysis of drill pipe in the well, the finite element analysis (FEA) model of 5″ API standard drill pipe is established. The mechanical characteristic of API standard drill pipe upset transition area is simulated, which can provide a reasonable reference for the optimization of the size of new types 5″ drill pipe upset transition as well as the practical application. Based on the simulation model, the factors affecting the stress distribution of the drill pipe upset transition area are obtained, and the new type of upset is developed.     

钻杆扭矩法预测冲击地压的研究

钻杆扭矩法是通过测试钻孔过程中钻机对钻杆输出扭矩的大小来判断煤矿冲击地压危险性的方法,具备许多传统方法不可替代的优点,是一种很有发展的预测预报方法。该文建立了钻屑过程中钻杆的力学模型,得出钻杆扭矩与煤体应力、煤体性质及钻进速度的关系,分析表明：钻屑过程中,煤体应力增大时,钻杆扭矩增大,钻屑推进力减小;钻屑推进速度增加时,钻杆扭矩增加,钻屑推进力增大;煤体强度增大时,钻杆扭矩增加,钻屑推进力增大。利用钻杆扭矩测试装置,测试了不同煤体应力条件下钻屑扭矩的变化规律。理论和实验结果均表明：使用相同的钻机及钻具,按照指定速度对同一性质的煤层打钻时,钻杆扭矩随着煤体应力的增大而增大,钻杆扭矩变化规律与煤体应力及钻屑量具有较好的一致性,通过测试钻杆扭矩的变化规律,得出钻孔处煤体应力场的分布化规律,进而预测煤层冲击危险性。研究结果为煤矿动力灾害预测预报提供一定的理论与实验基础。     

尺寸差异钻杆组成的钻柱中声传播特性测试

随钻实测信息声波传输技术是井下信息无线传输技术领域的一个重要研究方向。作为信息传输通道的钻柱是由尺寸存在差异的钻杆相连接构成,钻杆的尺寸差异对钻柱中声的传播是否存在影响是声载波选取及检测必须要了解的问题之一。建立了用于测试钻柱中声波传播特性的试验装置,对不同类型钻杆组成的钻柱中声波的传播特性进行了测试;利用基于声透层理论建立的钻柱中声传播特性研究模型对测试结果进行了理论分析。研究结果表明：组成钻柱的钻杆存在尺寸差异时,钻柱中声波传播特性有所改变,表现在通带的个数减少,有些通带消失,且通带的宽度变窄;尺寸存在差异的钻杆组成的钻柱中声衰减比周期性钻杆要大;低频通带声波受钻杆尺寸差异影响相对较小;存在着个别的排列方式,可以减小钻杆尺寸差异的影响。基于声透层理论的钻柱中声传播特性研究模型在计算前4个通带时较为准确。     

地质钻杆摩擦焊接组织和力学性能

探讨了地质钻杆用DZ60钢钻杆管体与40Cr钢钻杆接头的摩擦焊接性，并与采用热墩粗工艺生产的钻杆管体力学性能进行了对比。结果表明，摩擦焊接的地质钻杆具有良好的综合力学性能。     

有机热载体炉蛇形管失效原因分析

采用金相检验、力学性能测试、导热油化验等方法对某有机热载体炉发生火灾的原因进行了分析。结果表明：该事故的原因为使用的导热油标号过低,导致导热油在蛇形管内碳化、结焦,蛇形管过热,并产生蠕变裂纹,最终强度不足发生爆管。     

G105石油钻杆表面等离子渗氮组织和耐磨耐蚀性能分析

为了提高G105石油钻杆表面的耐磨耐蚀性能,通过在钻杆内部插入辅助阳极的等离子渗氮工艺对其表面进行处理,研究了不同测点深度对渗氮层组织和耐磨耐蚀性能的影响。研究结果表明:随着测点深度的增加,钻杆表面的温度表现出先增加后降低的变化规律,最大值发生在测点2。测点1～3部位形成了部分白亮层与扩散层,在白亮层中与试样表面平行的区域产生了黑色富氮层。按照从外往里的方向,渗层内的氮含量不断减小,在扩散阶段氮原子和铁原子发生结合并生成金属间化合物。通过离子渗氮处理后,试样腐蚀速率降低,渗层可以发挥良好的抗腐蚀性能,有效增强基体的耐蚀性。渗氮层摩擦系数减小至接近0.500的状态,随位置深度增加磨损率逐渐增大。在测点1～3部位磨痕表面较光滑平整,没有出现明显的犁沟、划痕等现象。     

Failure Analysis of Cracked Gear Shafts

Two gear shafts cracked during the fabrication. The cracks are through the grooves associated with the gear teeth and propagated completely across the shaft. Fractography on the cracked teeth indicates that the crack origins are about 3.5 to 4.0 mm from the groove and exhibit pointlike features. Fracture surfaces near the crack origin regions were intergranular, and the fracture appeared to have occurred instantaneously. Metallurgical analysis indicates that decarburization had occurred on the surfaces of the gear shafts, but occurrence of decarburization has no relation to the cracking. Cracking occurred during the carburization-quenching process and originated at a cluster of Al₂O₂ complex inclusions. The thermal stress produced by quenching drove the cracking process.