油田集输管线的腐蚀原因及对策研究

在油气田开发中,从钻井、开采、集输、到油气水处理、储运等生产的各个环节腐蚀都无处不在,无时不有,生产安全、人身安全和环境保护都受到影响。腐蚀是制约和影响油田生产的主要因素之一。油田已开发多年,各类埋地管线问题也日趋突出,各类穿孔产生的经济损失和安全问题已威胁到油田的可持续发展,只有进一步查出管线腐蚀的原因,减缓管线各类穿孔的发生,延长使用其寿命,才可能十分有效地控制油田腐蚀。本文通过分析油田集输管线腐蚀的影响因素,介绍集输管线的防腐技术,使我们有能力采取及时有效措施进行预防和控制,尽量降低管线腐蚀程度,减少管线穿孔几率,延长管线的使用寿命,确保油田的正常生产和运行。     

宝浪油田含油污水腐蚀行为的研究

采用XRD分析、X射线衍射、电子探针和电化学试验方法,研究了宝浪油田含油污水处理系统主要设备腐蚀产物、腐蚀形貌和腐蚀原因,并对腐蚀影响因素进行了试验研究.结果表明,污水处理系统中设备主要存在CO2腐蚀、O2腐蚀和SRB腐蚀,通过试验发现,改变含油污水的pH值、温度和SRB含量等对污水的腐蚀性有不同程度的影响.找出了宝浪油田污水腐蚀的主要原因及影响因素,为油田污水处理系统防腐蚀提供了参考依据.     

20和L245NS钢在模拟低含硫饱和CO2油田污水中的电化学耐蚀行为研究

为了解决低含硫油田污水处理过程引起管线腐蚀问题并有效选材,研究了20和L245NS 2种管线钢在不合硫和低含硫的饱和CO2油田污水环境中的耐蚀行为,利用动电位极化、有效电化学阻抗谱、扫描电镜和能谱仪等方法研究了2种材料在含硫和不合硫环境中电化学腐蚀行为和腐蚀产物的元素成分分析.结果 表明:20和L245NS管线钢在低含...     

靖边油田腐蚀机理及防腐蚀措施

靖边油田属于超低渗油田,其已进入高含水开发期,综合含水不断上升,存在大量的腐蚀性物质,导致油井井下管柱的腐蚀日趋严重,也造成油田集输和注水系统中的钢质管线腐蚀严重,不但影响油田的正常生产,而且带来了材料维修及更换费用。为了有效地解决油田油井管柱的腐蚀问题,通过对靖边油田西部区块腐蚀现状的调查,系统分析并研究其腐蚀原因,以降低成本为宗旨,研究开发了井筒及地面管线整套防腐蚀的配套技术,包括油井专用缓蚀剂、环氧防护层+牺牲阳极阴极保护技术和优化外加电流阴极保护技术。     

浅谈油田地面管线的腐蚀失效

随着油田的开发与建设,油田地面管线的长度不断增加,而由于管线腐蚀造成的各种直接损失和间接损失是极其惊人的,因此必须对管线腐蚀给予高度关注。     

硫酸盐还原菌的去极化作用

研究了硫酸盐还原菌（ＳＲＢ）在ＰＨ＝７－１２的油田污水中的生长情况，并通过测量油田污水的极化曲线，分析了ＳＲＢ对腐蚀电极过程的影响。结果表明，ＳＲＢ在ＰＨ＝７－９时大量繁殖生长，在ＰＨ＝１１时不能存活。在油田污水中，ＳＲＢ对腐蚀的阳极过程影响不大，以阴极却有显有去极化作用而加快了钢铁腐蚀，用透射电镜进行形貌观察发现，ＳＲＢ存在二种形态；有鞭毛的弧状菌和无鞭毛的杆状菌。     

pH值对低碳钢在高含盐污水中的腐蚀影响

为了防止油田地面输油管线穿孔,利用动电位扫描法和缝隙腐蚀实验研究了pH值对低碳钢在某油田高含盐污水中腐蚀行为的影响：结果表明：随着pH值的升高,低碳钢的均匀腐蚀速度逐渐下降,但当pH值超过某一临界值后(约8．5),缝隙腐蚀开始加剧;该临界值与低碳钢发生钝化时的pH值相一致：探讨了pH值对缝隙腐蚀的影响机理。提高污水的pH值,能降低碳钢的均匀腐蚀速度,但pH值过高易引起碳钢的缝隙腐蚀。因此,pH值应小于8．5。     

掺水管道的腐蚀与防护

油田掺水管道的穿孔泄漏现象较为普遍,管道穿孔泄漏后即造成了环境污染,同时也给采油队的生产管理带来了安全隐患,维修班天天堵漏,但仍然天天有漏,针对掺水管道穿孔泄漏频繁,掺水管线使用寿命短这个问题,通过现场对掺水管线腐蚀原因进行调查认为掺水管道主要是钢管外腐蚀,腐蚀位置集中在几个点;而不是整条管道均匀分布,导致这种现象的发生其主要原因是管道初次穿孔修复后防腐遭到破坏,管道腐蚀加速,穿孔周期缩短,不但增加了生产单位的工作量,同时也影响了管线的使用寿命。     

输油管道阴极保护技术的研究与探索

输油管线多数以钢管为主,土壤是特殊的电解质,长距离大口径的金属管道埋人地下必然要遭受严重的腐蚀。由于部分原油外输管道的外防腐层老化破损以及阴极系统长期欠保护等因素。造成管道腐蚀不断加剧。 本文针对目前大庆油田输油管线的腐蚀状况,以油田外输管线庆一哈输油管道为代表,埋地原油外输管线的腐蚀机理及规律进行了研究、对管线现有阴极保护系统进行了测试分析及评估优化。研究结果表明：输油管线在上壤中的腐蚀是氧还原的腐蚀过程．管线钢的自腐蚀电位及腐蚀速度受土壤的湿度及含氧量影响较大。为控制和减少管线的腐蚀穿孔,提出更换长效参比电极、个别地段加牺牲阳极、加强对阴极保护系统的管理与监测的优化方案。     

对掺水管道的腐蚀与防护的认识

油田掺水管道的穿孔泄漏现象较为普边,管道穿孔泄漏后即造成了环境污染,同时也给采油队的生产管理带来了安全隐患,维修班天天堵漏,但仍然天天有漏,针对掺水管道穿孔泄漏频繁,掺水管线使用寿命短这个问题,通过现场对掺水管线腐蚀原因进行调查,通过调查认为掺水管道主要是钢管外腐蚀,腐蚀位置集中在几个点,而不是整条管道均匀分布,导致这种现象的发生其主要原因是管道初次穿孔修复后防腐遭到破坏,管道腐蚀加速,穿孔周期缩短,不但增加了生产单位的工作量,同时也影响了管线的使用寿命。     

电磁场作用下的粉末成形固结技术研究进展

外加电场或磁场作用下粉末成形固结技术是快速制备高性能材料的新途径。应用前景广阔。重点综述了外加电场作用下放电等离子烧结技术和外加磁场作用下动磁压制技术的原理、特点及应用情况。并展望了今后粉末成形固结技术的研究方向。     

均匀场聚焦带状注速调管电子光学系统的研究

本文系统地阐述了均匀场聚焦带状电子注的传输理论,设计了柱面阴极皮尔斯电子枪,模拟显示轨迹的层流性较好;设计了产生均匀磁场的磁聚焦结构,在1 m长的距离内,成功地实现了X波段100 MW带状电子注的稳定传输,电子注通过率达到100%;同时设计了收集极新型结构,给出了电子注在收集极内的发散情况。     

Effects of High Magnetic Field on Solidification and Corrosion Behaviors of Magnesium Alloy

The solidification behaviors of AZ61 magnesium alloy under a high magnetic field were studied. The corrosion property of AZ61 alloy was investigated in a solution of 3.5 mol/L NaCI by measuring electrochemical p.olarization. The results show that the high magnetic field can refine microstructure and benefit aluminum transfer. The crystal of α-Mg is induced to orient with their c-axis parallel to the magnetic field. The corrosion studies indicate that different crystal plane of magnesium has different corrosion property. The passivating films on the α- and b-planes have higher corrosion resistance than that on the c-plane. Aligned structure affects the corrosion property of AZ61 magnesium alloy.     

一种细化金属凝固组织的新方法

提出了用强脉冲磁场改善金属凝固组织的新技术。实验结果表明，强脉冲磁场能把铝合金的凝固组织从粗大的树枝晶细化为等轴晶，而且磁场愈强，细化效果愈显著。强脉冲磁场细金属凝固组织的新技术可应用于各金属材料，并可在工业上推广应用。     

Induced Magnetic Field Used to Detect the Sigma Phase of a 2205 Duplex Stainless Steel

Sigma phases are formed due to heat treatments and/or welding processes during the solidification stage, and they are responsible for embrittlement of duplex stainless steels. Only a small amount of this phase promotes unfavorable mechanical properties and liability to corrosion. In this work, a new affordable approach to detect and follow-up the kinetics of the sigma phase transformation is evaluated. The measurements are based on an induced magnetic field generated through the interaction between an external magnetic field and the microstructure under study. To validate this approach, the induced magnetic field values are compared with the values of the Charpy impact energy, and the sigma phase is assessed by optical microscopy. Moreover, surface fractures are analyzed by scanning electron microscopy and X-ray diffraction. The results from the 2205 duplex stainless steel used show that there is a direct relation among the impact energy, fracture mechanism and induced magnetic field. The method proved to be able to follow up the embrittlement of the DSS successfully. Moreover, the results confirm that the presence of a sigma phase can be studied based on an induced magnetic field, even when in low amounts, and that a critical threshold value can be defined to monitor structures in service.     

Field dependence of switching currents in an exchange biased spin valve

Current induced magnetic reversal due to spin transfer torque is a promising candidate in advanced information storage technology. It has been intensively studied. This work reports the field-dependence of switching-currents for current induced magnetization switching in a uncoupled nano-sized cobalt-based spin valve of exchange biased type. The dependency is investigated in hysteretic regime at room temperature, in comparison with that of a trilayer simple spin valve. In the simple spin valve, the switching currents behave to the positive and the negative applied magnetic field symmetrically. In the exchange biased type, in contrast, the switching currents respond to the negative field in a quite unusual and different manner than to the positive field. A negative magnetic field then can shift the switching-currents into either negative or positive current range, dependently on whether a parallel or an antiparallel state of the spin valve was produced by that field. This different character of switching currents in the negative field range can be explained by the effect of the exchange bias pinning field on the spin-polarizer (the fixed Co layer) of the exchange biased spin valve. That unidirectional pinning filed could suppress the thermal magnetization fluctuation in the spin-polarizer, leading to a higher spin polarization of the current, and hence a lower switching current density than in the simple spin valve.     

磁场方向对碱腐蚀构建多晶硅绒面结构的影响

在零磁场和2T、4T磁场中用NaOH溶液腐蚀制备多晶硅绒面结构,样品板平面分别平行和垂直于磁场放置。用电子天平称重表征硅片的腐蚀程度、用奥林巴斯LEXT OLS4100共聚焦显微镜观察多晶硅片形貌、用Ocean Optics USB4000光谱仪测量多晶硅片的反射率、用WT-1200硅片测试仪测量样品的少子寿命,研究了磁场方向对碱腐蚀构建多晶硅绒面结构的影响。结果表明：随着磁感应强度的提高多晶硅片的腐蚀程度严重,绒面结构变得均匀和细腻,反射率降低;在磁感应强度相同的条件下碱液中沿着磁场方向运动的OH^-离子不受磁场力作用,而运动方向与磁场方向不完全一致的OH^-离子受磁场产生的Lorenz力作用。Lorenz力使板平面垂直于磁场方向的硅片样品腐蚀程度更加严重、绒面和断层状结构细腻程度更加显著、少子的寿命更长、反射率更低。磁感应强度为4T时反射率降低到14.5%,在用碱液腐蚀制备多晶硅绒面结构过程中施加强磁场,板平面垂直磁场方向放置硅片减反射效果更加显著。     

强磁场对过共晶铝硅合金中初晶Si分布的影响

对Al-18% (质量分数) Si合金进行磷盐变质处理,分别在变质剂反应温度保温20,40min,发现不施加强磁场条件下,凝固组织中的初晶Si相集中在试样周边附近,试样中心处为共晶组织.施加强磁场条件下,凝固组织中的初晶Si相分布在整个试样中.施加强磁场后试样中的初晶Si的尺寸比没有被施加强磁场的试样中的初晶Si尺寸大.     

Finite-Element Calculations of Remote Field Eddy Current Interactions with Slit Defects

Abstract

Remote field eddy current (RFEC) excitation is a promising approach for detection of the very fine axial cracks typical of stress corrosion cracking (SCC) in pipelines. Interactions between adjacent cracks or slits can enhance responses in some cases. Detailed finite-element modeling was undertaken to establish the behavior and interactions of multiple slits such as those occurring in SCC. Three different field/slit configurations are considered, with anomalous source models used to aid interpretation of the results. The study noted that magnetic perturbations generated by ferromagnetic material tend to be vanishingly small, and that the interactions between multiple cracks give minimal enhancement, indicating that eddy current rather than magnetic field excitation is best for the detection of SCC. With eddy current excitation, field perturbations are generated by even very fine slits, and are larger in non-ferromagnetic material. For non-ferromagnetic pipes, the perturbations tend to merge as a circumferential separation between parallel axial cracks decreases, resulting in significant interaction and signal enhancement.