Benefits of Dielectric Oil Regeneration Systems in Power Transmission Networks: A Case Study

The criticality of transformers and reactors in the power transmission network and the paramount importance of ensuring their reliability through maintenance of the insulating oil is known. This paper presents a comprehensive examination of the efficacy and economic viability of a dielectric oil regeneration system, as implemented by the Transmission System Maintenance Department (TSMD) of the Independent Power Transmission Operator (IPTO), Greece’s sole transmission operator. Through a detailed chemical analysis and performance evaluation, we assess the impact of the regeneration system on treated insulating oil quality over multiple cycles. The study reveals that the electrical properties of the insulating oil are fully restored after regeneration, negating the need to fully replace it, while the investment becomes cost-neutral within weeks from the commissioning of the regeneration system. This economic analysis, coupled with the system’s environmental benefits of reducing waste oil generation, positions the dielectric oil regeneration system as a compelling solution for the maintenance of power transmission assets.

Cade Oil Poisoning: A Case Series

Objectives and Study: Cade oil is aromatic oil obtained from the branches and wood of Juniperus oxycedrus, common in the Mediterranean region and widely used in traditional medicine. This oil contains many chemical compounds with neurological, cardiac, renal, respiratory, hepatic, and gastrointestinal toxicity. Cade oil poisoning often requires intensive care admission due to the severity of the clinical picture. The objective of this study is to highlight the multiple manifestations found in the pediatric population due to cade oil exposure objectifying its significant toxicity. Methods: The authors report during this article a series of five cases of cade oil poisoning on pediatric patients hospitalized in the pediatric intensive care unit of El HARROUCHI hospital at the CHU Ibn Rochd in Casablanca during the period from 11/01/2022 to 12/07/2022. The patients have been exposed, a few hours before their admission, to an external cade oil application used by parents for therapeutic purposes. Main Findings: Our patients were aged from 1 month to 4 years, the average age was 1.5 years with a female predominance and a sex ratio of 1.5:1. The patients had no prior medical history, and the cade oil application was spontaneously declared by the parents of only 2 patients, 3 of them reported the use of it after the detection of the substance by the clinician. For all the cases, cade oil was applied to treat fever. All five (5) patients presented initial neurological signs. 3 of them were admitted to an acute consciousness disorder and the 2 other patients presented respectively a convulsive status epilepticus and generalized-onset seizure. We report respiratory symptoms in 4 cases ranging from a simple caught, rhinorrhea to severe respiratory distress. Three patients presented acute liver failure with very high transaminase levels associated with acute kidney failure. Two of them presented digestive symptoms such as abundant hematemesis, vomiting, and watery diarrhea. All patients received high doses of N acetylcysteine in their initial treatments. The evolution was unfavorable for 4 patients who developed a multiorgan failure, 3 of them died, with a good clinical improvement in the fifth patient after supportive and symptomatic treatment. Conclusion: Cade oil poisoning remains a very frequent situation in our context. Its toxicity is widely described in the literature. The increasing number of cases admitted, and the seriousness of the clinical picture require mass awareness among the population and the scientific community toward the use of medicinal plants.

Multistring analysis of wellhead movement and uncemented casing strength in offshore oil and gas wells

This paper presents a theoretical method and a finite element method to describe wellhead movement and uncemented casing strength in offshore oil and gas wells.Parameters considered in the theoretical method include operating load during drilling and completion and the temperature field,pressure field and the end effect of pressure during gas production.The finite element method for multistring analysis is developed to simulate random contact between casings.The relevant finite element analysis scheme is also presented according to the actual procedures of drilling,completion and gas production.Finally,field cases are presented and analyzed using the proposed methods.These are four offshore wells in the South China Sea.The calculated wellhead growths during gas production are compared with measured values.The results show that the wellhead subsides during drilling and completion and grows up during gas production.The theoretical and finite element solutions for wellhead growth are in good agreement with measured values and the deviations of calculation are within 10％.The maximum von Mises stress on the uncemented intermediate casing occurs during the running of the oil tube.The maximum von Mises stress on the uncemented production casing,calculated with the theoretical method occurs at removing the blow-out-preventer （BOP） while that calculated with the finite element method occurs at gas production.Finite element solutions for von Mises stress are recommended and the uncemented casings of four wells satisfy strength requirements.

Heating of heavy oil by circulating hot water in closed double casing in ultra-deep wells

In heavy oil production,the loss of energy to ambient surroundings decreases the temperature of the heavy oil flowing upwards in a vertical wellbore,which increases the oil viscosity and the oil may not flow normally in the wellbore.Therefore,it is necessary to lower the heavy oil viscosity by heating methods to allow it to be lifted easily.Heating of heavy oil in an oil well is achieved by circulating hot water in annuli in the well（tubing-casing annulus,casing-casing annulus）.In this paper,based on heat transfer principles and fluid flow theory,a model is developed for produced fluids and hot water flowing in a vertical wellbore.The temperature and pressure of produced fluids and hot water in the wellbore are calculated and the effect of hot water on heavy oil temperature is analyzed.Calculated results show that the hot water circulating in the annuli may effectively heat the heavy oil in the tubing,so as to significantly reduce both oil viscosity and resistance to oil flow.

A Case Study on the Occurrence and Mobility of the Shale Oil from the Muli Coalfield,Qilian Mountain

Shale oil occurs in free state （including condensate state）, adsorption state （adsorbed on kerogen and mineral particles） and dissolved state （dissolved in natural gas, residual water, etc.） in shales and adjacent layers. The characterization of the occurrence of different hydrocarbons in shale oil, especially the quantitative separation of free hydrocarbons （mobile oil）, has been the current focus of shale oil research. Taken the shale oil from the Muli coalfield in Qilian Mountain as an example, this work extracted shale samples with organic solvents of different polarity to obtain different occurrence states of hydrocarbons in the oil-bearing shale and to reveal the compositional differences of the hydrocarbons. The result may provide new geochemical information for the occurrence and mobility of shale oil.

Oil Spill Model Operational Application in Damage Assessment and Case Study of Validation

Oil spill modeling is an important technical measure to evaluate the impact of oil spills scientifically. Because of the great uncertainty in its early development, simulation results have not been used as the basis of judgments for environmental compensation cases. Despite this, scientific research institutes in many countries, including China, are still devoted to the research and development of oil spill models and their applications in environmental damage assessment, which makes it possible to apply them in the judicial arbitration of damages claims. The relevant regulations on the Chinese compensation fund for oil pollution damage from ships and the judicial authentication of environmental damage have also accredited such kind of modeling applications. In order to enhance the applicability of oil spill model further, it is necessary to expand its damage assessment function, and to test, calibrate and verify the accuracy of the evaluation. To this end, the author adopts the self-developed 3-dimentionaloil spill model—CWCM to simulate the “Tasman Sea” oil spill accident. By comparing the simulation results of tidal current field, wind field, oil spill trajectory with those observed, the model coding and parameter selection are corrected, and it is realized that the simulation being basically consistent with the measured results. In addition, the results of the scale reduced simulation test of oil spill weathering are applied verifying and perfecting the weathering model of CWCM. The technical requirements and process for operational application of oil spill model in judicial arbitration are also put forward. In view of the rapid simulation function, the operational updating program for oil spill weathering model, coupled current model and dynamic update wind field diagnostic model are put forward in order to further improve the operational evaluation function and evaluation efficiency of oil spill model.

Three-Dimensional Finite Element Numerical Simulation and Physical Experiment for Magnetism-Stress Detecting in Oil Casing

The casing damage has been a big problem in oilfield production. The current detection methods mostly are used after casing damage, which is not very effective. With the rapid development of China's offshore oil industry, the number of offshore oil wells is becoming larger and larger. Because the cost of offshore oil well is very high, the casing damage will cause huge economic losses. What's more, it can also bring serious pollution to marine environment. So the effective methods of detecting casing damage are required badly. The accumulation of stress is the main reason for the casing damage. Magnetic anisotropy technique based on counter magnetostriction effect can detect the stress of casing in real time and help us to find out the hidden dangers in time. It is essential for us to prevent the casing damage from occurring. However, such technique is still in the development stage. Previous studies mostly got the relationship between stress and magnetic signals by physical experiment, and the study of physical mechanism in relative magnetic permeability connecting the stress and magnetic signals is rarely reported. The present paper uses the ANSYS to do the three-dimensional finite element numerical simulation to study how the relative magnetic permeability works for the oil casing model. We find that the quantitative relationship between the stress' s variation and magnetic induction intensity's variation is: Δδ =K* ΔB, K = 8.04×109, which is proved correct by physical experiment.

稠油热采井射孔孔眼应力分析及影响因素

针对稠油热采井生产过程中,射孔井段套管频繁出现损伤断裂的问题,基于弹塑性和热力学理论,采用有限元方法建立注汽—焖井—生产过程射孔套管有限元热力学耦合模型,对各阶段射孔套管应力分布特征进行研究,并开展不同射孔参数下射孔套管强度影响规律分析。研究表明:生产过程中射孔孔眼位置出现明显应力集中现象,在温差及内外压差等共同作用下,注采前期套管应力最大可达498.16 MPa,并逐渐产生塑性失效现象,当注采作业完成时,套管塑性失效现象最严重;随着射孔相位角增大,射孔密度对Mises应力值的影响逐渐减小,而套管孔眼最大应力与射孔相位角成反比关系。该研究对延长稠油热采井射孔套管使用年限和保障正常生产作业具有十分重要的意义。

轧制方向对新型125KSI高钢级油套管性能的影响

利用室温拉伸试验、冲击试验、断裂韧性试验检验了超深井用新型125KSI高钢级油套管中沿扎向和垂直于扎向的强度、塑性、冲击韧性和断裂韧性。通过OM、SEM和EDS技术,对显微组织、晶粒长宽比和夹杂物分布进行了分析,讨论了显微组织对油套管各种性能的影响。结果表明,油套管材的微观组织由板条状回火马氏体和均匀弥散分布的细小Al_(2)O_(3)-MnS类混合夹杂物组成,晶粒为8.5级。轧制后,沿管道轧制方向的晶粒长宽比增加,导致强度增加,塑性降低且平行于管道轧向的冲击韧性下降;沿管道轧制方向的夹杂物分布更加集中,导致临界距离变小,裂纹扩展方向垂直于轧制方向的断裂韧性降低。

基于YOLOv5的油气井套管接箍检测方法

针对目前在可视化测井领域,利用人工对测井视频中的接箍进行识别校深时存在的检测效率低下、检测误差高的问题,提出一种基于YOLOv5算法的接箍智能检测方法。首先对井下的接箍图像进行采集,在缺乏公开数据集的情况下,通过数据增强的方法制作接箍数据集,再对增强后的数据集使用labelimg工具进行数据标注,然后将标注好的数据集送入YOLOv5网络中进行训练,最后使用训练好的最佳权重进行接箍识别并计数。测试结果表明,该方法能实现对当前测井视频中接箍的准确识别,接箍计数的正确率为100%,并且检测效率高,平均每帧检测时间为15 ms。

案例教学法在“油气层保护”课程中的应用

在新时代背景下,社会需要的是理论知识丰富、实践能力较强的复合型人才,若是沿用传统的教学模式,难以培养出符合社会需求的人才。案例教学法作为一种新型的互动教法,可有效弥补传统教学模式缺乏互动性、实践性的问题,促进复合型人才的培养。基于此,以油气层保护课程为主要研究对象,对其教学现状进行分析,并对案例教学法在该课程中的应用策略进行探讨,以其为相关专业教师提供参考。

5Cr油套管钢在含Cl^(-)的CO_(2)环境中的腐蚀特性研究

目的掌握油气井生产中CO_(2)腐蚀对油套管的影响规律,研究兼顾耐蚀性和经济性的5Cr油套管材料在含Cl^(-)的CO_(2)环境中不同时间下的腐蚀演变规律。方法采用XRD、XPS、SEM和EDS等技术分析5Cr油套管钢在不同时间下腐蚀产物膜的演变情况,利用丝束电极(WBE)和阻抗测试(EIS)技术对其腐蚀电化学行为进行研究。结果5Cr油套管钢腐蚀后期的平均腐蚀速率约为初期的1/2,在腐蚀14 d后,腐蚀产物膜中的Cr富集大于30%,Cr、Fe质量比达到较高水平,约为基体的15倍。随着腐蚀的进行,电荷传递电阻和产物膜覆盖引起的电阻增大,电化学反应阻力增大。在腐蚀前期具有局部不均匀性,随着腐蚀的进行,电极腐蚀电位有负移现象,最终分布区间为−0.59~−0.61 V,电极表面阳极电流区域大幅减少。结论在腐蚀时间延长的条件下,5Cr油套管钢腐蚀产物膜的致密性增加,电荷传递电阻呈变大趋势。在产物膜下的5Cr油套管钢区域,电流发生由阴极向阳极极性转变的现象,产物膜存在的孔隙使5Cr油套管钢基体金属被腐蚀,从而导致阳极电流的出现。表面局部腐蚀电位阳极区的形成和扩展使其有产生点蚀的倾向,但腐蚀产物逐渐沉积在点蚀坑内壁,形成了Cr富集的保护性表面层,原发生点蚀区域由原阳极活性点位转变为阴极区,对其发展起到了抑制作用。

复合磨损套管爆裂失效机理及剩余强度预测

超深井、水平井、大位移井等复杂油气井服役工况异常恶劣,套管复合磨损严重,将对井筒完整性构成巨大威胁,且磨损套管剩余强度难以精准预测。为此,基于塔里木盆地塔中北坡顺南区块501井套管磨损数据及P110管材应力—应变本构关系,建立了充分考虑钻杆本体和接头联合造成的磨损模式、夹角、磨损重叠深度及磨损深度的复合磨损套管有限元力学模型,并开展了多种复合磨损模式下套管弹塑性变形、屈服、裂纹萌生、扩展及爆裂行为模拟,得到了不同复合磨损套管应力分布、剩余抗内压屈服强度及爆裂强度。研究结果表明:(1)月牙夹角在0°~90°时,应力干涉削弱应力集中,月牙夹角在90°~180°时,应力干涉增强应力集中,这种交互作用机制导致磨损套管剩余强度随着月牙夹角增加而先增加后降低;(2)裂纹萌生并起始于等效应力最大的位置即磨损月牙中心,并垂直于最大环向应力沿径向从套管内壁向外壁扩展,且裂纹一旦萌生,裂纹将迅速扩展并发生爆裂失效;(3)灰色关联度分析确定了复合磨损套管剩余强度对磨损深度、月牙夹角、复合磨损形式、月牙重叠深度的敏感性,分析结果表明磨损深度是决定套管剩余强度的主控因素。结论认为,该认识为套管强度设计与优化提供了技术参考,并对准确预测复合磨损套管剩余强度和确保井筒安全及完整性具有重要意义。

深层环境下固井水泥水化放热特性及井周温度场演化规律研究

塔里木盆地已建成我国最大的超深层油气生产基地,深层环境会对水泥水化放热特性产生一定的影响,研究深层环境下水泥水化放热及传热特性对明确井周温度场演化规律至关重要。文章首先根据现场实测资料建立了塔里木油田近井和远井地层温度方程,根据不同地层深度的温度分布情况,开展了不同温度下G级水泥水化放热实验,基于Krstulovic-Dabic(K-D)经典水化动力学模型,结合水泥成核结晶与晶体生长、相边界反应以及扩散三过程反应特征推导了不同温度下水泥水化放热预测曲线,进一步推导了套管-水泥环-地层热传导模型,并将放热曲线作为热源代入到有限元模型中,得到了不同井深的套管与水泥在水化放热与高温地层的共同作用下温度场的变化情况。研究结果可为下一步分析有限局部空间的温度场变化对地层压力和套管变形影响提供技术支持。

侏罗系油井套管破损原因分析及采油工艺防腐措施优化

在侏罗系油井套管破损严重区块典型油井套管破损规律和破损原因调研分析的基础上,通过室内试验和现场腐蚀监测结果,探讨加深花管采油工艺防腐措施的可行性。结果表明:典型套管破损位置均在动液面以下,即主要集中在1000 m以下管段;套管破损以内腐蚀穿孔为主要特征,套管破损井段平均温度约为60℃;含水率及CO_(2)含量过高是导致套管发生腐蚀的主要原因;加深花管的采油工艺防腐措施使油套环空中油水界面位置下移,从而避开CO_(2)腐蚀的敏感温度区间,其在一定程度上可缓解侏罗系油井套管的腐蚀程度,但需与其他配套防护措施联合使用。最后,指出了采油工艺防腐措施的进一步优化方向。

油气人工智能课程实践案例融合与效果评价

人工智能时代下,各行业的交叉学科建设也在不断探索中。针对“油气人工智能”交叉学科的教学建设这一问题,文章研究探索了基于案例式的油气人工智能教学模式。文章从油气人工智能教学的选题模式、学习模式、课程实践模式等方面进行分析,通过具体的教学实施,开展了案例库建立、案例融合教学实践以及教学反馈评价等教学活动,可以为油气人工智能课程的建设提供启发。

油气井套损风险预测及防控软件研制及应用

针对套损作用机理复杂、主控因素难以厘清、防控措施制定不科学等问题,开展了基于数据驱动的套损风险评价预警防控策略研究。对油气井基本数据和套损样本进行数据预处理和主控因素分析,用机器学习算法进行样本训练,建立“二分类”套损预测模型,预测套损的概率,优化完井和生产参数,制定油气井套损防控策略。开发了基于B/S架构的油气井套损风险评价预警防控软件,并链接了A2数据库,实现了某油田2400井层套损防控的实时预警和优化。研究应用表明:建立的预测模型和软件可以对油气井套损原因及防控策略形成认知,可以实现老井、新井、待补层井套损预防对策的优化。

φ139.7 mm×12.7 mm CB125HC 高抗挤套管 抗外挤性能研究

利用实物试验和有限元模拟研究了几何参数对高抗挤套管抗挤性能的影响。检测10支同批次φ139.7 mm×12.7 mm CB125HC套管的外径、壁厚等几何参数,利用立式挤毁试验系统进行挤毁试验,得到套管抗挤强度值。对检测的几何参数和挤毁结果进行分析,研究壁厚不均度、椭圆度等对套管抗挤能力的影响。利用实测数据建立有限元模型,计算各个样品的抗挤强度值并与API计算值和实测值进行比较。结果表明:高抗挤套管的抗挤强度远大于API计算值,说明API公式不适用于高抗挤套管,有限元结果与试验结果相近,用有限元方法可快速预测高抗挤套管的抗挤能力。

浅层取换套修井作业的井口切割装置设计与分析

在油井下井过程中,套管钳会对套管的连接螺纹产生损伤,套管在井中也容易受到腐蚀,导致取换过程中套管卸扣困难,需要对套管进行迅速的切割处理。然而,由于井口作业的空间有限,现有的套管取换方法费用高、周期长、动力紧张且油田生产现场不能出现明火。基于此,设计一种包括扶正机构、切割机构、传动机构、切割刀具四部分的浅层取换套修井作业的井口切割装置。通过ANSYS等软件对主要零部件进行分析,结果表明:该装置具有体积小、安装方便、切割工作安全可靠、切割效率高等优点,可实现快速切割套管的功能,从而提高作业效率,降低成本。

考虑井筒完整性的固井方案风险评价方法

在吉木萨尔页岩油藏开发过程中,压裂导致井筒完整性失效的问题严重,不同固井方案下的失效位置和比例差异较大。为研究固井方案对压裂时井筒完整性的影响,基于该地区固井现状构建了二开特征水平井Ⅰ井和Ⅱ井,分别选取这2口井在一开、二开井段的相同位置及Ⅰ井水泥环与钻井液的固液交界处作为关键节点进行研究。采用有限元软件模拟压裂施工对井筒的影响,明确了压裂时不同固井方案下井筒不同位置处套管和水泥环的应力分布规律,分析了全井筒多节点的失效风险,优选了固井方案。研究结果表明:B环空内是钻井液时油层套管的Mises应力明显大于是水泥环时,损伤风险更大;B环空中水泥环的受力大于C环空,且顶部有较高拉伸破坏风险,底部有较高压缩破坏风险;固井方案Ⅰ相较于方案Ⅱ完整性失效风险低。风险评价及优选结果可为拟压裂井的固完井方案设计提供指导,为优选安全经济的固完井方案提供参考。