Dynamic evaluation of a scaled-down heat pipe-cooled system during start-up/shut-down processes using a hardware-in-the-loop test approach

Micro-mobile heat pipe-cooled nuclear power plants are promising candidates for distributed energy resource power genera-tors and can be flexibly deployed in remote places to meet increasing electric power demands.However,previous steady-state simulations and experiments have deviated significantly from actual micronuclear system operations.Hence,a transient analysis is required for performance optimization and safety assessment.In this study,a hardware-in-the-loop(HIL)approach was used to investigate the dynamic behavior of scaled-down heat pipe-cooled systems.The real-time features of the HIL architecture were interpreted and validated,and an optimal time step of 500 ms was selected for the thermal transient.The power transient was modeled using point kinetic equations,and a scaled-down thermal prototype was set up to avoid mod-eling unpredictable heat transfer behaviors and feeding temperature samples into the main program running on a desktop PC.A series of dynamic test results showed significant power and temperature oscillations during the transient process,owing to the inconsistency of the rapid nuclear reaction rate and large thermal inertia.The proposed HIL approach is stable and effective for further studying of the dynamic characteristics and control optimization of solid-state small nuclear-powered systems at an early prototyping stage.

长庆气区关停气井挖潜措施技术与展望

长庆气区天然气资源丰富,天然气田均为低渗—致密气田,主要以致密气为主。随着气田开发深入,存在气区关停井、低产井“存量大、分布广、复产难”实际问题,为气区的长期效益稳产带来艰巨挑战。文章通过开展长庆气区关停井措施挖潜实践及应用评价,结合气井动静态特征,分析气井关停的形成原因及技术难点,优选挖潜措施类型,优化工艺参数,强化效果评价,初步形成了“储层挖潜、井筒治理、地面配套”三大评价挖潜措施工艺技术系列,实施挖潜井1497口,累计增气超50×10^(8) m^(3),成效显著。随着长庆气区天然气勘探开发不断推进,气藏“埋藏深、储层薄、单井产量低、水气比高”特点更加突出,还需进一步开展老层剩余储量挖潜、层间储量动用、井筒复杂处理、积液停产井快速复产及综合治理、地面工艺技术配套等技术攻关,以实现气田气井挖潜措施工艺关键技术的迭代升级,更好支撑长庆气区的稳产及长远发展目标。长庆气田老井措施挖潜及增产技术体系的建立,助力了长庆气区的增储上产,为长庆气区稳固国内战略大气区地位及长期发展提供了较好的参考及借鉴。

Study on durability of Pt supported on graphitized carbon under simulated start-up/shut-down conditions for polymer electrolyte membrane fuel cells

The primary issue for the commercialization of proton exchange membrane fuel cell（PEMFC） is the carbon corrosion of support under start-up/shut-down conditions. In this study, we employ the nanostructured graphitized carbon induced by heat-treatment. The degree of graphitization starts to increase between 900 and 1300 ℃ as evidenced by the change of specific surface area, interlayer spacing, and ID/IG value. Pt nanoparticles are deposited on fresh carbon black（Pt/CB） and carbon heat-treated at 1700 ℃（Pt/HCB17） with similar particle size and distribution. Electrochemical characterization demonstrates that the Pt/HCB17 shows higher activity than the Pt/CB due to the inefficient microporous structure of amorphous carbon for the oxygen reduction reaction. An accelerating potential cycle between 1.0 and 1.5 V for the carbon corrosion is applied to examine durability at a single cell under the practical start-up/shutdown conditions. The Pt/HCB17 catalyst shows remarkable durability after 3000 potential cycles. The Pt/HCB17 catalyst exhibits a peak power density gain of 3%, while the Pt/CB catalyst shows 65% loss of the initial peak power density. As well, electrochemical surface area and mass activity of Pt/HCB17 catalyst are even more stable than those of the Pt/CB catalyst. Consequently, the high degree of graphitization is essential for the durability of fuel cells in practical start-up/shut-down conditions due to enhancing the strong interaction of Pt and π-bonds in graphitized carbon.

Dynamic Model and Performance of Absorption Heat Pump in Shut-down Process

The dynamic model of LiBr absorption heat pump in shut-down process is established. The simulation results show good agreement with the experiments. The dynamic performance of high-pressure generator, low-pressure generator and heat exchanger are analyzed in detail. The proper shut-down mode of the heat pump is presented,which, in consideration of solution parameters, has a great effect on the possibility of crystallization of some components.

Simulation of Reciprocating Compressor Start-up and Shut-down under Loaded and Unloaded Conditions

During the start-up and shut-down phase of reciprocating compressors, the loads on all components of driven train system are very high. In this paper a method for calculating the forces on coupling, e-motor, crank shaft as well other components of the system will be described. The modelling of the electrical induction motor, coupling, crank shaft, damper as well as the compressor resistance torque are extremely important in simulating start-up and shut-down of reciprocating compressor. Furthermore the switching torque of the electrical motor and the instantaneous moment of inertia of the reciprocating compressor crank gear are important as well. The transient start-up and shut-down process under loaded and unloaded conditions is described using a non-linear differential equation for driven train system： E-motor--coupling--flywheel--reciprocating compressor--damper. Shaft torsional moments on the drive train and especially on the coupling, whether elastic or stiff, can then only be calculated using numerical simulation. This paper will describe some of the key elements in modelling, simulating and measurements of drive train start-up and shut-down carried out on already operational piston compressor units.

稠油蒸汽吞吐后期关停井恢复再生产地质因素正交分析方法

稠油油藏由于原油黏度大、流动性差,多周期吞吐后,近井地带含油饱和度下降幅度大、产量低、连续吞吐效益比较差。但是关停一个时期后,油藏内部再次达到动态平衡,剩余油会在这类井附近再次富集,开井生产仍能获得一定的产量和经济效益。河南稠油油田开展了这方面的矿场试验,并取得了比较好的效果。矿场试验过程中,采用正交试验法,通过数值模拟技术分析了不同地质条件下的剩余油富集程度,利用极差分析法得到了影响蒸汽吞吐关停井剩余油再富集的地质因素排序为原油黏度、渗透率、纯总厚度比、孔隙度、油层厚度、油藏埋深、油藏倾角,并利用方差分析法进一步验证了该结果。依据这一研究成果确定了15口目标井恢复再生产,成功率80.0%。这一研究思路和方法可为东部老油田提高资源利用率提供参考和借鉴。

利用井底压力采集短接准确计算地层压力的方法

介绍了现有技术情况下求取欠平衡地层压力的方法以及存在的缺点,在此基础上研制了井底压力采集短接,通过现场试验,实测出关井求压过程中井下气液两相流时的井底压力,根据常规试井理论和地层渗流理论建立一种利用实测数据计算地层压力的新方法,该方法是在井筒内建立压力平衡,采用实际测量出的平衡点的井底压力,消除了套压、立压不稳定以及钻井液密度不准带来的误差,准确计算出该井段各分层地层压力的大小。该方法非常接近实际地层压力,使关井求压计算值误差降低4%左右。

特低渗油藏长停井恢复技术

针对延长油田特低渗油藏低产、低效长期停产井的特点,根据长停井形成的不同原因,应用水力喷射径向钻孔、补孔、选择性堵水、复合堵水、DRIVE解堵、二氧化氯解堵等治理技术对长停井进行治理。在现场应用中结合完善井网、注水井分注、注水井调驱技术,改善区块整体开发水平。在现场应用后,取得了较好的措施效果,并形成了长停井挖潜配套恢复技术,提高了特低渗油田注水开发水平。

宁东油田ND26井区长期关停后开发动态特征研究

针对宁东油田ND26井区长期关停后地层能量恢复、压力分布及产能变化等问题,综合运用油藏工程等方法开展关停期间地层能量恢复程度、压力分布规律及试采特征等研究。研究表明,油田关停期间地层压力逐渐恢复,影响压力恢复的主要因素有储层物性、构造部位以及井型;关停期间地层流体重新分布,剩余油向构造高部位富集,油水界面较原始状态已抬升10.0m,构造高部位的复产油井产量恢复快、含水上升幅度小;油井关停再复产不仅能够节能降耗、不改变油田最终采收率,而且有利于地层能量恢复,延长油田的开发寿命。

欢喜岭油田开发中后期长停井挖潜研究

欢喜岭油田共有各类停产井1815口,占全油田总井数的59.5%,其中长期停产关井的有1063口。长期停产井中,油气井952口,注水井111口,严重影响了油气产量。因此,2006年针对长期停产的油气井进行了综合分析研究,实施了侧钻、压裂、封堵等工艺技术措施。措施后,部分长期停产的油气井恢复了产能,2006年全年累计生产原油71660m3。

油田长停井复产探讨

随着油田开发时间的延长,井况不良井、高含水井以及因其它因素引起的不能正常生产的油水井越来越多,长停井比例越来越大。大量油水井长期停产停注,一方面限制了油田采油注水能力,另一方面导致油田注采系统不完善,两者均严重制约了油田的高效开发和正常生产。通过对长停井状况、停产原因、复产潜力及复产方法等进行研究和探讨,旨在最大限度地利用现有资源和设备来提高油田油水井利用率,改善油田开发效果,提高油田经济效益。

气井远程控压开关技术在神木气田的探索与试验

神木气田是我国典型的低渗透气田,集输采用井下节流、中低压集气工艺(设计压力6.3 MPa),由于电磁阀为两位式阀门,无法实现远程控压开关井。目前,该气田气井开关井频繁,为了降低员工开关井作业的劳动强度,提升神木气田数字化管理水平,2018年进行了气井远程控压开关井试验,在10口气井安装了电动针阀和电动球阀。通过试验发现,两种阀门均实现了高压气井(套压高于3.8 MPa)的远程控压开关井,达到了将传统的井口开关井作业转变为中控室远程操作的目的。同时,安装的阀门在当年回收成本后,从增产气量和节约人工操作成本两方面每年可增收200万元以上,具有良好的推广价值,为低渗气田后期开发起到了很好的借鉴作用。

渤海某凝析气田气井井筒积液分析及处理措施

针对凝析气藏开发过程中存在产量递减、气井高含水及井筒积液等问题,以渤海某凝析气田关停气井为研究对象,利用气井生产动态分析方法,结合气井的系统测试资料,明确了关停气井井筒中的积液段,利用经验公式法及Pipesim软件计算了临界携液气量、优化了气井生产管柱。为保证关停气井复产后正常生产,提出气举、涡流排液、泡排、小直径管等排液采气措施建议及实施步骤。对E4、E5、E6井井筒积液进行分析,其中E6井根据建议措施复产后,初期日产气2.3×10^4 m^3,日产油15 m^3。根据前期生产动态,预测五年累产气约584×10^4 m^3。该方法可为海上凝析气田井筒积液分析及关停井复产措施提供借鉴。

大牛地气田关停水平井复产潜力评价

为了适应稳产及提高产量的要求,展开大牛地气田关停水平井复产潜力评价研究。综合关停水平井的钻遇情况和生产特征进行评价,将关停水平井由好到差依次分类进行分析,最后结合关停原因及以往复产经验,给出关停水平井治理顺序及治理建议。

浅谈城市自备井的关停封填与保护

地下水的私采滥用已成为保护地下水的大敌。通过法律手段和强有力的行政手段,将城市供水管网覆盖的自备井全部实施关停封填。确保了城市用水安全,有利于城市供水设施的充分利用。

关停水平井复产潜力评价技术研究与应用

气田开发过程中由于水淹、出砂、产能过低等原因,导致水平井无法生产处于关停状态。目前关停井治理缺少理论依据及指导原则,为确保治理措施的有效性,提高气田开发经济效益,研究从分析影响复产潜力因素入手,引入复产潜力指数,利用模糊计算等数学方法,创新建立了气井复产潜力指数评价方法,准确评价关停井复产潜力。该方法在大牛地气田关停井治理中应用效果良好,根据复产潜力计算结果,结合气井特征、现场工艺措施,制定出不同类型关停水平井治理计划,对今后气田关停井复产潜力评价与治理具有很好的指导意义。

电动潜油柱塞泵举升工艺超负荷停井原因

电动潜油柱塞泵举升工艺作为机采井的一种新型节能举升工艺,经过10多年的研究与试验,使工艺结构日趋成熟,但部分试验井频繁出现超负荷停井问题。结合葡萄花油田现场试验数据,采用统计分析方法,得出电动潜油柱塞泵的直线电动机设计安全系数,即当实际泵深与直线电动机理论扬程之比小于或等于40%时,可以满足工艺运行需求,保证油井运行时率,为电动潜油柱塞泵举升工艺的进一步推广提供借鉴。

井下智能找水、堵水技术在渤海油田水平井中的应用

目前,渤海油田水平井高含水的问题日益凸显,由于井深结构原因,水平井水突进后,含水率会直线上升,严重的造成水淹。为了减缓水平井含水上升速度,提高油田开发效果,针对不同水平井的特点,引进了井下智能开关装置,采取智能分段找水、堵水技术,在现场一批水平井中成功应用,控水增油效果显著。

曹妃甸油田井间压力预测及关调制度研究

为保障曹妃甸油田加密调整井钻完井作业安全,减少溢流、漏失等钻井复杂情况和事故发生,根据曹妃甸油田地质和开发特点,通过室内实验和数模相结合的方法,研究分析了不同关调制度下的井间压力变化规律。基于调整井间压力变化规律及预测模型,建立了基于卡尔曼滤波算法的注采关系确定新方法,形成了强边底水油藏和弱边底水油藏调整井周边注采井关调制度确立方法。经2口井现场应用表明,在确保加密调整井钻完井作业安全的前提下,新建立的周边注采井关调制度较传统关调方式分别降低关调量62%和54.5%,应用效果良好。研究结果可有效预测加密调整井井间压力,合理关调周边注采井,对保障调整井施工安全具有重要意义。

论沧州市自备井关闭对城市地质环境的影响

沧州市位于华北平原东部,属严重资源型缺水地区。自20世纪70年代大量开采深层淡水,地下水水位持续下降,地下水降落漏斗不断扩展,并引发了地面沉降等一系列城市环境地质问题。本文对比分析了关闭自备井和城市集中供水水源地前后地下水漏斗扩展方向和-50 m漏斗封闭面积的变化,以及地面沉降年沉降速率的变化,论述了自备井关闭对城市地质环境的影响。