Inter-stage performance and energy characteristics analysis of electric submersible pump based on entropy production theory

The electric submersible pump(ESP) is a crucial apparatus utilized for lifting in the oil extraction process.Its lifting capacity is enhanced by the multi-stage tandem structure, but variations in energy characteristics and internal flow across stages are also introduced. In this study, the inter-stage variability of energy characteristics in ESP hydraulic systems is investigated through entropy production(EP) analysis,which incorporates numerical simulations and experimental validation. The EP theory facilitates the quantification of energy loss in each computational subdomain at all ESP stages, establishing a correlation between microscopic flow structure and energy dissipation within the system. Furthermore, the underlying causes of inter-stage variability in ESP hydraulic systems are examined, and the advantages and disadvantages of applying the EP theory in this context are evaluated. Consistent energy characteristics within the ESP, aligned with the distribution of internal flow structure, are provided by the EP theory, as demonstrated by our results. The EP theory also enables the quantitative analysis of internal flow losses and complements existing performance analysis methods to map the internal flow structure to hydraulic losses. Nonetheless, an inconsistency between the energy characterization based on EP theory and the traditional efficiency index when reflecting inter-stage differences is identified. This inconsistency arises from the exclusive focus of the EP theory on flow losses within the flow field, disregarding the quantification of external energy input to the flow field. This study provides a reference for the optimization of EP theory in rotating machinery while deeply investigating the energy dissipation characteristics of multistage hydraulic system, which has certain theoretical and practical significance.

Establishing Submersed Macrophytes via Sinking and Colonization of Shoot Fragments Clipped off Manually

In this paper, sinking and growth of apexes and mid-stems of Myriophyllum spicatum L., Hydrilla verticillata （L.f.） Royle and Ceratophyllum demersum L. in concrete ponds containing eutrophic water and sediment were investigated. Sinking rates of apexes and mid-stems reached 34.8% and 4.4% at the 6 th day and 91.1% and 66.7% at the 22 nd day for M. spicatum, 57.8% and 55.6% at the 6 th day and 100% and 97.8% at the 22 nd day for H. vertieillata, 18.9% and 86.7% at the 6 th day and 95.6% and 100% at the 22 nd day for C. demersum, respectively. Most sunken fragments established themselves successfully with significant growth. Total shoot length ofplantlets developed from apexes and mid-stems increased by 399% and 61% for M. spicatum, 593% and 256% for H. vertieillata and 114% and 104% for C. demersum, respectively. The results showed that it was feasible to establish submersed macrophytes via sinking and colonization of shoot fragments clipped off manually.

Oxidative Degradation of 4-chlorophenol in Aqueous Induced by Plasma with Submersed Glow Discharge Electrolysis

The oxidative degradation of 4-chlorophenol （4-CP） in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography （HPLC）. Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe^2＋ were examined. The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation,

Periphyton Biomass Response to Phosphorus Additions in an Aquatic Ecosystem Dominated by Submersed Plants

An experiment was conducted to investigate the response of periphyton biomass to addition of phosphorus (P) in an aquatic ecosystem dominated by submersed plants. Aquatic ecosystems dominated by Hydrilla verticillata (L.f.) Royle and Vallisneria natans (Lour.) Hara were constructed in mesocosm aquaria. Mesocosms were dosed weekly with different P loads (0 μg/L/Week and 100 μg/L/Week) for 17 weeks. Total P (TP), total soluble P (TSP), and soluble reactive P (SRP) concentrations in the waters of mesocosms added with P were significantly higher as opposed to the unenriched control mesocosms. The biomass of the attached periphyton and the cover of floating periphyton remained abundant in P-unenriched control mesocosms throughout the test period with a TP, TSP, and SRP concentration ranging of 0.021 - 0.049 mg/L, 0.004 - 0.024 mg/L, and 0.003 - 0.018 mg/L, respectively. P addition caused the decline of attached periphyton biomass to a low level and loss of floating periphyton. Results indicate that P enrichment in an aquatic ecosystem dominated by submersed plants could reduce attached periphyton biomass and eliminate floating periphyton. The research would be useful to maintain periphyton by reducing excessive P in aquatic ecosystem dominated by submersed plants.

Effects of competitive interactions of different life forms submersed plants on biomass allocation in shallow lakes

Plant competition has been recognized as one of the most important factors influencing the soructure and function of lake ecosystems. Competition from plants of dissimilar growth form may have profound effects on shallow lakes＇. An experiment was conducted to investigate the effects of competitive interactions of submersed plants with dis- similar growth forms on the biomass allocations. Hydrilla verticitlata and Vallisneria natans were selected and were planted in a single-species monoculture and a mixed-species pattern, Results showed that the growth of E natans was＇ significantly affected by the tt, verticillata and caused a sharp reduction of biomass, but the root：shoot ratio of E ha- tans was not affected significantly and there was a minimal increase in mixture： while for H. verticillata, the biomass and the root：shoot ratio were not significantly changed by the competitive interactions ore natans, there was minimal increase of biomass and minimal decrease of the root：shoot ratio. These results may indicate that theplant which can develop a dense mat or canopy at the water surface would be a stronger competitor relative to the plant that depends more on light availability near the sediment.

Energy Consumption Analysis and Optimization of Electric Submersible Pump System

Electric submersible pumps account for a considerable proportion in the development of the Bohai Oilfield. Improving the system efficiency of the electric submersible pump wells, ensuring that the units operate in the high-efficiency zone, is essential. Analysis shows that the efficiency of the electric submersible pump system depends on the wear and tear of each component of the submersible pump equipment, the setting of operational parameters, and more importantly, the production status and daily management level of the oil well. Therefore, improving the structural performance of the submersible pump product, optimizing the parameters setting of the oil well, strengthening daily management, establishing a scientific management system, and improving the production management process and system can effectively improve the production efficiency and economic benefits of the oil well, and further achieve the goal of energy saving and emission reduction. In addition, it is necessary to actively promote the concept and technology of energy saving and emission reduction, encourage oilfield enterprises to explore effective measures to reduce the energy consumption of the electric submersible pump system by strengthening the scientific management system, and achieve a green, low-carbon, and high-quality development of oilfield production to achieve the unity of economic benefits, social benefits, and environmental benefits. This article applies the above measures in the P oilfield to achieve energy optimization of submersible electric pump systems, reducing the daily power consumption of single well submersible electric pump systems by 371 kWh per day, increasing the submersible electric pump's lifespan by 200 days, generating considerable project benefits.

基于实测数据的半潜式平台贝叶斯模型修正方法研究

随着半潜式平台的长期海上服役,平台的基本设计参数会发生变化,如仍基于原始设计参数对平台进行分析将影响结果的准确性。本文以半潜式平台服役中易发生变化的基本参数(平台排水量、重心高度和三个自由度回转半径)作为修正参数,以平台横摇、纵摇和垂荡自由度的方差和波频功率谱密度构建目标函数,建立可依据实测数据的半潜式平台贝叶斯参数修正方法。以我国某半潜式平台实测数据为例,开展平台的参数修正研究,并基于修正后的参数对平台多年一遇环境荷载下的响应进行对比评估。

地浸采铀注液井小直径潜水泵抽水洗井试验

某地浸采铀试验采区注液井周边含矿层堵塞严重。注液井套管内径仅有80 mm,在常规空压机抽水洗井结束后,在3口注液井中开展了小直径潜水泵抽水洗井试验。初始抽水量均在4.5 m_(3)/h左右,期间最小抽水量为3.4 m_(3)/h,其中2口井的第1股最浑浊洗井水的含砂量分别为4.36、5.19 kg/m_(3)。粒度、电镜扫描和化学组成分析显示,洗井水沉降干渣中的矿物碎屑主要为粉砂、细砂碎屑,少量黏土碎屑;化学沉淀主要是CaCO_(3)、MgCO_(3)和FeCO_(3);潜水泵抽水洗井累计运行约27.5 h,未出现任何故障。试验表明,小直径潜水泵抽水洗井可行且投资少、成本低、安全性高、实施方便。

潜水系统非稳定流抽水试验智能优化配线

精确求解水文地质参数是地下水数值模拟、地下水资源评价与开发的前提。为此,基于抽水试验降深—时间数据,采用随机权重粒子群优化(RandWPSO)算法对考虑给水滞后的博尔顿模型智能优化配线,实现潜水完整井非稳定流水文地质参数反演。结果表明,RandWPSO算法选择的曲线拟合参数精度r/D值为0.1753,较人工选择的0.2精确度更高。该方法显著提高了反演参数精度,可为曲线族标准曲线拟合方法在实际工作中难以应用的问题提供借鉴。

局部系泊失效下半潜式平台系泊韧性评估方法研究

半潜式平台系泊失效会引发重大安全问题,为研究局部系泊失效下半潜式平台系泊韧性水平,构建系泊失效至恢复全过程的平台性能水平曲线,并将系泊韧性量化为吸收、适应及恢复3部分。基于平台运动响应及恢复操作构建相应的韧性定量评估指标,并利用CRITIC(Criteria Importance Through Intercriteria Correlation)法进行赋权,进而得到韧性评估3层指标体系。以规则波作用下的南海某半潜式平台为实例,在ANSYS@AQWA TM中建立其数值模型以进行水动力计算,并运用构建的评估指标体系进行系泊韧性评估。结果显示:半潜式平台系泊韧性水平与吸收、适应和恢复能力具有一致相关性,且浪向对角线立柱下两根系缆同时失效时系泊韧性水平最高,同一立柱下两根系缆同时失效时系泊韧性水平最低。

深水半潜式钻井平台水下设备作业虚拟仿真教学平台构建

深水油气钻井与陆地及浅水的同类作业存在显著差异,给海洋油气工程专业学生的现场实习、实践带来了诸多困难。为加深学生对深水油气钻井工程装备的认知,采用虚拟仿真技术,构建还原度高、实战性强的深水半潜式钻井平台水下设备作业虚拟仿真教学平台,实现隔水管运移存储及下放、隔水管与上部升沉补偿装置及底部立管总成的连接、水下防喷器结构及安装等功能,帮助学生在无需前往深水平台的前提下、在虚拟环境中系统掌握水下设备的操控方法及作业程序,提升学生的深水钻井作业的工程实践能力。

考虑翘曲应力的半潜平台扭转极限强度计算方法研究

半潜平台由于结构和受力复杂,目前主要采用非线性有限元整体模型计算其扭转极限承载力,存在建模和计算时间较长、精度较差和不易收敛等问题。一方面进行半潜平台的整体有限元模型的简化研究,提高其计算效率和收敛性;另一方面基于薄壁杆件理论,将该半潜平台截面简化为单壁室截面计算其翘曲应力,提出了基于一跨模型且考虑翘曲应力影响的半潜平台约束扭转极限强度计算的简化增量迭代方法,并编制了相应的计算程序。计算结果表明,所提简化增量迭代方法计算精度较高,能很好地反应翘曲应力对半潜平台约束扭转极限强度的影响,大幅减少了计算约束扭转极限强度的时间,可用于半潜平台的设计。

载人潜水器有机玻璃视窗蠕变-疲劳特性分析

通过对棒状有机玻璃试样进行短期蠕变试验,揭示载人潜水器视窗玻璃材料的蠕变特性。开展有机玻璃蠕变断裂试验,获得有机玻璃材料的蠕变断裂寿命,给出蠕变断裂时间和保载应力水平成双对数线性相关的结论及相应的线性拟合方程,并开展拉伸疲劳试验获得不同峰值应力下的拉伸疲劳寿命。对300 m观光潜器有机玻璃视窗在不同下潜深度下的应力水平进行分析,并结合基于线性累计损伤理论的时间寿命分数法,实现对300 m载人潜水器有机玻璃视窗考虑保载蠕变的疲劳寿命估算。

地浸采铀用潜水电泵泵轴结构与材料优选

泵轴断裂、泵体腐蚀导致潜水电泵损毁率高。通过理论计算和ANSYS数值模拟,对六棱轴和圆柱轴结构的强度、刚度等力学特性进行了对比,并开展了304、316L、904不锈钢材料的耐腐蚀现场对比试验。结果表明:在同等载荷和等效直径条件下,圆柱轴的圆截面所受剪切应力为六棱轴的64.95%,且扭转角度仅为六棱轴的56.25%;模拟结果显示圆柱轴联轴器最大环向形变为六棱柱轴最大环向形变的68.4%,圆柱轴结构的抗扭性能更优;904不锈钢抗腐蚀性能最佳,但304和316L不锈钢对酸性介质具有类似抗腐蚀性能。综合考虑耐腐蚀余量和制造成本,建议在地浸采铀专用潜水电泵研发过程中选用圆柱泵轴结构,沿用现有316L不锈钢作为主材的选材方案。

基于无模型自适应控制的半潜式平台运动性能研究

南海海域油气资源极其丰富,半潜式平台在该海域工作时常常面临着系泊失效这一重大危险情况。该研究以一艘装配有悬链式系泊系统和DP-3动力定位系统的半潜式平台为研究对象,利用AQWA软件开展系泊失效前后半潜式平台运动性能研究。同时,借助于AQWA软件二次开发功能,将无模型自适应控制作为动力定位系统控制理论,以研究半潜式平台系泊失效后运动性能恢复。数值仿真模拟结果表明,采用无模型自适应控制作为动力定位系统控制理论的半潜式平台能很好地恢复系泊失效后的运动性能,有效地减小系泊失效带来的危害;基于偏格式动态线性化和全格式动态线性化的无模型自适应控制比基于紧格式动态线性化的无模型自适应控制能让半潜式平台更快地恢复运动性能。

“深海一号”半潜式生产储油平台长距离湿拖方案论证

针对“深海一号”半潜式生产储油平台拖航方案设计及工程实施面临拖航距离远、拖航路径环境恶劣、拖船资源选择少,以及作业风险高等众多技术难题,通过对比分析平台干拖和湿拖方案,重点分析湿拖过程中的拖航路线、平台吃水、湿拖阻力、拖船配置等关键技术问题,通过水池模型试验验证该方案的可行性,顺利实施了“深海一号”平台的长距离湿拖工作。

矢量泵喷推进潜航器回转性能研究

泵喷推进器已经逐渐成为现代潜航器的首选,矢量推进器也在航空航天领域得到了广泛的应用。为了解决传统依赖船舵控制在低航速下控制效率低的问题以及提高潜航器回转性能,矢量推进器在潜航器上的应用已逐步成为国内外关注的热点。本文考虑大舵角(喷管偏角)下潜航器各参数非线性的影响,建立潜航器水平面操纵运动的非线性模型。通过仿真研究分析船-舵-推进器、船-矢量推进器和船-舵-矢量推进器三种不同的控制方法下潜航器在低航速、控制泵喷推进器转速、控制潜航器轴向航速三种不同条件下作水平面回转运动时的回转性能,结果表明矢量泵喷推进器可以有效改进潜航器的回转性能。

气液两相条件下叶片开孔对电潜泵性能和内部流场的影响

为了研究电潜泵内部流动机理,从而改善高含气工况下电潜泵的气液混输性能,文中基于欧拉-欧拉非均相流模型,对不同入口含气率工况下叶片开孔前后的气液两相流动特性进行了数值模拟分析,探究了气液两相流条件下叶片开孔对电潜泵性能和内部流场的影响.结果表明,在纯水工况以及低含气率、小流量工况下,叶片开孔会降低电潜泵性能;但是叶片开孔可以改善电潜泵在大流量下的气液混输性能.叶片开孔后会改变叶轮内部压力分布,使电潜泵叶轮内部平均压力升高,进而改善叶轮内部流态.叶片开孔后会冲散气相聚集,使气体分布更加均匀,叶轮流道内涡核分布明显减少,减少了能量耗散.该研究为改善电潜泵气液混输性能提供了理论依据.

空间导叶式多级离心泵级间能量损失机理

为探究空间导叶式多级离心泵级间能量损失的原因,以1个单级和1个3级潜水泵为研究对象,通过试验和数值模拟相结合的方法,分析其级间能量损失的机理.对单级和3级潜水泵分别进行全流场外特性试验.基于ANSYS软件对3级潜水泵不同流量点进行数值模拟和内流场分析,着重对各级叶轮进口流态、内部旋涡结构和叶片载荷分析比较.结果表明:小流量工况下,3级潜水泵各级扬程接近且与单级扬程相差不大;额定流量工况和大流量工况下,3级潜水泵第1级扬程与单级扬程仍相差不大,但后2级扬程相比于第1级降低了6%~10%.随着流量的增大,首级叶轮来流稳定性不受影响,其后各级叶轮进流流态变差.后2级叶轮进口液体介质冲角变化使其对叶片进口边的冲击增大.后2级叶轮进口处的涡在流量较大时发展为流向涡,从而引起叶片载荷突变,削弱了叶轮做功能力,导致后2级能量损失.研究结果可为多级离心泵的设计提供理论依据.

深海载人潜水器直流无刷电机驱动控制研究

为提高深海载人潜水器电机工作效率和故障诊断能力,并降低系统工作噪声,对直流无刷电机的高效低噪驱动控制技术进行研究。采用具有智能相位控制功能的三相全波正弦波控制芯片TB6605结合智能功率模块(IPM)设计直流无刷电机驱动器。采用单片机对系统的电压、电流、温度、转速、位置信息进行检测,为控制系统提供必要的信息反馈,对应用直流无刷电机的系统状态起到实时信息监测的功能。实验结果表明,研制的直流无刷电机驱动器在电机全转速范围内具有较高的工作效率,额定工况点效率高达90%以上,且在全转速范围内,提高了电机运转的平稳度,降低了系统噪声。研究成果对提高深海载人潜水器电机的工作效率和故障诊断能力,并降低系统工作噪声具有很好的支撑作用。