油田套管P110钢腐蚀的影响因素

油田油套管腐蚀大,影响因素较多,为了提高管道的使用寿命,给油气田的防腐蚀提供理论依据,采用动、静态高温高压釜对油井套管P110钢进行了失重法腐蚀试验,利用SEM,EDS和XRD技术对P110钢的动、静态CO2腐蚀行为进行了研究.结果显示,CO2腐蚀产物膜的主要成分是FeCO3和Fe3C;在每种条件下,温度、CO2分压、Cl-浓度对P110钢的腐蚀速率都有其临界值.     

温度对注气井P110油管钢耐蚀性能的影响

目前,对于注气工况下井筒存在的氧腐蚀问题及其影响因素研究较少。利用高温高压反应釜进行腐蚀模拟试验,辅以失重法、SEM、EDS、XRD等测试手段,研究含氧工况下温度对P110油管钢耐蚀性能的影响。结果表明:温度通过改变溶液中的氧含量、电化学反应速率、溶解氧的扩散作用以及表面产物层而影响P110钢耐蚀性能。温度升高,电化学反应加速,溶解氧扩散加快,CaCO_3垢层脱落,腐蚀速率增大;溶解氧含量下降,又会导致腐蚀速率下降。温度的双重作用导致P110腐蚀速率先增大后减小,100℃时最大,且会发生局部腐蚀。     

酸性X气田生产井环空套管腐蚀规律研究

酸性X气田生产过程中多口井出现了环空带压和环空气/液样含H₂S和硫化物的现象,油层套管中110SS抗硫材质面临严重的腐蚀风险。为了获取真实井筒环境下抗硫套管的腐蚀规律,在高温高压反应釜中采用腐蚀挂片的方法开展了110SS抗硫套管在气相和受污染环空保护液中的腐蚀评价实验,以及抗硫套管与镍基合金套管连接处在受污染环空保护液中的电偶腐蚀评价实验,并利用金相显微镜、扫描电镜和能谱对试样腐蚀表面和腐蚀产物进行了观察分析。实验结果表明：抗硫套管在液相中的腐蚀速率很低,温度对腐蚀速率没有明显的影响;当温度高于100℃时,抗硫套管在气相中的腐蚀变得非常严重,腐蚀速率高达0.947 3 mm/a;抗硫套管和镍基合金套管连接处在液相中发生了严重的电偶腐蚀,抗硫套管试样表面出现较大的腐蚀坑,腐蚀速率大于工程设计允许的0.076 mm/a。获得的真实井筒环境下的抗硫套管腐蚀规律将为后期制定防腐控制措施、预测套管剩余强度以及评价井筒安全提供准确的参考依据。     

P110钢抗冲刷腐蚀行为研究

采用高温高压釜,利用扫描电子显微镜(SEM)、能散X射线谱仪(EDS)和X射线衍射(XRD)技术,并辅以失重法对油套管钢P110在不同条件下的CO2腐蚀速率和行为进行了研究,探讨了在流动介质中多种因素对油套管钢腐蚀造成的影响,并以此提出了P110钢抗冲刷腐蚀的机理.     

除氧剂的添加对注气井油管管材腐蚀行为的影响

为研究注入水中添加亚硫酸钠除氧剂控制注气井管柱氧腐蚀的有效性,为现场注气井管柱腐蚀防护提供依据,采用高温高压反应釜对注气井油管管材进行腐蚀模拟试验,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)等对试样腐蚀产物膜的成分及结构进行表征,研究了除氧剂添加对管材腐蚀行为的影响,并初步讨论了其腐蚀机理。结果表明:因注氮气驱油工艺引入的溶解氧会对P110与P110S油管管材带来严重的腐蚀风险,并具有较高的局部减薄失效风险; P110与P110S管材的全面腐蚀速率分别达到1.511 mm/a与1.404mm/a,最大减薄速率达到12.085 mm/a与4.240 mm/a;通过在注入水中适量添加除氧剂,P110与P110S管材的全面腐蚀速率分别降低至0.035 mm/a与0.030 mm/a,有效地降低了管材的腐蚀风险。     

油田注水井的腐蚀风险研究

注水井在输送注入水的同时,可能会引入溶解氧、微生物和结垢等腐蚀性因子,对油井管柱的安全运行带来挑战。通过模拟研究工况环境,开展P110油套管钢在注入水中的高温高压腐蚀评价试验及细菌腐蚀试验,利用失重法测试腐蚀速率,利用扫描电镜(SEM)及能谱仪进行腐蚀形态观察和腐蚀产物分析,研究了油井管在注入水后的腐蚀风险。结果表明:注入水引入的溶解氧、SRB和垢沉积均会导致P110钢腐蚀速率明显增加,且存在一定的局部腐蚀敏感性。     

P110S在高温CaCl2完井液中的腐蚀规律研究

面对日益苛刻的井下腐蚀工况,关于油井套管在高温CaCl2完井液中的服役性能有待进一步明确.同时,CO2侵入、管体塑性变形等也会对油管的耐蚀性及开裂敏感性产生影响.为此,利用高温高压反应釜进行腐蚀模拟试验,采用失重法、电化学法、SEM、XRD测试分析等手段,对P110S在高温CaCl2完井液中的腐蚀行为进行了研究.结果表明:在无应力、无CO2侵入时,P110S在CaCl2完井液中无局部腐蚀风险,但提高温度会导致其腐蚀速率上升;在210℃时,P110S的腐蚀速率会因为CO2的侵入明显上升且有局部腐蚀风险;在210℃、无CO2侵入工况下,P110S的塑性变形区存在严重的局部腐蚀风险.     

P110与P110S钢在套管环空液中的腐蚀行为研究

为进一步提高油气田勘探开发效率,通过腐蚀速率、腐蚀产物及微观形貌分析,分别研究了P110和P110S 2种钢材料在油田注采井套管环空液中于高温、中温及低温条件下的腐蚀行为.结果 表明:2种钢材料在同样温度和环空液条件下腐蚀表现基本一致,一套环空液中P110与P110S最大腐蚀速率均为0.65 mm,二套环空液中2种材料的腐蚀速率在100℃时达到最大值,P110最大腐蚀速率为0.04 mm/a,P110S最大腐蚀速率为0.03 mm/a.同时,3D形貌仪分析显示2种材料在一套环空液中于140℃腐蚀后表面有局部腐蚀的初期迹象.最后,进行了CO2渗入条件下P110S钢材料腐蚀行为及机理研究,结果显示CO2渗入加剧了高温条件下钢材料的腐蚀速率,并且得出其发生局部腐蚀的机理是CO2电化学腐蚀.     

海上W油田P110保温油管腐蚀行为的试验研究

目前对P110保温油管在高含CO2气体分压的井筒中的腐蚀情况研究较少;主要考虑CO2分压与温度影响,较少考虑腐蚀介质含水率的影响;腐蚀试验周期一般在120 h以内,较短的试验周期容易造成腐蚀速率测试结果偏高,且目前较少有P110钢腐蚀速率的预测模型.为此,模拟油田腐蚀环境,通过高温高压反应釜动态旋转挂片法进行腐蚀试验,借助SEM形貌观察及XRD物相分析等手段研究了温度、CO2分压、腐蚀介质流速、含水率等因素对P110保温油管腐蚀行为的影响.结果 表明:低温务件下腐蚀产物结构松散,容易脱落,对基体保护效果较差,以全面腐蚀为主;80℃时腐蚀产物膜较厚,含有较多的孔洞与缝隙,局部腐蚀作用明显;高温条件下产物膜由较规则的晶粒组成,致密均匀,对基体有较好的保护作用,为全面轻度腐蚀.腐蚀速率随温度升高先增加后减小,80℃时腐蚀速率出现极值4.73 mm/a;随CO2分压的升高呈线性关系增加;随着腐蚀介质流速的增加指数关系增大;随腐蚀介质含水率的升高呈平方关系增大.基于试验结果,建立了多因素腐蚀速率预测模型,可为工程上P110保温油管腐蚀速率预测提供参考.     

H2S,CO2酸性环境中110ksi钢P110,C110套管的应力腐蚀速率

110 ksi钢级C110,P110套管在酸性油气田环境服役过程中受到应力和腐蚀的双重作用,其腐蚀速率与静态的结果不同。如何利用室内试验结果为现场选材提供依据,目前研究尚不充分。采用挂片法、高温高压恒载荷应力腐蚀试验装置和高温高压三点弯曲应力腐蚀试验装置测试了60℃,10MPa,10%（体积分数,下同）H₂S,20%CO₂酸性环境中,P110,C110套管钢分别在自由状态、拉应力以及剪应力状态下的腐蚀速率。结果表明:在酸性环境中,套管钢承受应力作用时会发生应变老化,腐蚀速率显著增大;腐蚀作用在缺口敏感和应力集中部位尤为明显,这些特殊结构部位将形成微裂纹并持续扩展,造成套管钢力学性能和使用寿命降低。本方法适合受应力和腐蚀双重作用下管材腐蚀速率的测试。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。