注水井转抽技术研究及其应用

低渗透油田采用水驱方法效果较差,最终采收率只有20%。为此,开展了注水井转抽现场试验研究。根据室内实验和水驱油渗流机理,阐述了油田注水井微观出油机理和宏观出油机理,应用理论计算分析和数值方法,定量分析认为,影响注水井转抽效果的主要因素有启动压力、毛管力、到断层的距离、孤立砂体有效厚度等。通过室内核磁共振实验和孔隙结构分析,阐明了换向驱油（注水井转抽）可以提高采收率,在此基础上,从总结矿场试验资料入手,通过地质基础和开发特征研究,提出了适合注水井转抽的地质条件：转抽的注水井要取得较好效果,则注水井到断层的距离应大于50m,或该井钻遇孤立的中高渗透砂体且有效厚度应大于3m。     

低渗透油藏开发效果综合评价方法及应用

大庆油田低渗透油藏开发水平差异较大,尤其是老区块存在着可采储量不足、剩余油分布零散、含水高等制约油田发展的症结。为此,在分析低渗透油藏开发特征的基础上,开展低渗透油藏开发效果综合评价方法及应用,优选反映低渗透油藏开发水平特点的5类14项参数。以朝阳沟油田扶余油层为目标储层,复核储集层实际开发水平,落实开发潜力,解决开采中出现的问题。通过校正区块井数和有效厚度,沿用套改其他参数,选用容积法复算区块的地质储量;应用模糊综合评判方法,建立不同类型区块开发效果评价标准,分析影响评价指标的主控因素,依据井网形式、开发现状,找差距、找问题、找潜力,制定一类区块水驱调整对策。结果显示,一类区块水驱效率提高,年均含水下降0.36个百分点,两年时间老井综合递减率下降0.6个百分点。目前已在朝阳沟油田扶余油层31个区块应用开发效果综合评价方法,实践表明,其适应性和可操作性较好,取得了良好的增效成果,具有推广应用前景。     

涠洲油田低渗储层长岩心驱替实验研究

中海油在南海西部海域的涠西南凹陷发现低渗透油气田。目前,该油田开发面临的主要问题包括:特低渗(渗透率小于10×10-3μm2)油藏储量所占比例大,如何提高低渗透储层产能,如何有效动用储量,以及注水开发可能存在注入能力低等。由于地层原油黏度低,油质较轻,注气开发是提高低渗透油藏采收率的有效手段;此外,该油田开发过程中将产生大量伴生气,有足够的气源。因此,采用油田伴生气回注是值得探索的提高采收率的方法。为此,有必要通过长岩心驱替实验,对低渗透油气田的注入方式进行评价优选,为编制海上低渗透油田开发方案提供依据。选取涠洲某油田流沙港组低渗透储层,通过室内长岩心驱替实验研究,综合评价了衰竭、水驱、气驱、气/水交替驱替时的驱油效率和渗流特征,从而为注水、注气驱提高采收率开发方式的选择提供实验数据支持和参考。实验结果表明:衰竭式开采方式效果最差,注水比注气效果要好,注液化气前置段塞+外输气驱的方式,能够达到最好的驱替效果。     

低渗透油田注水开发注水水质问题研究

我国油田拥有丰富的低渗透油田储量，虽然近十几年来许多新技术、新工艺、新材料、新方法用于油田开发，但注水开发仍是这些油田开发的主要方式，占有很大的比例。为了增加低渗透油田注水开发的采收率，对注水水质问题的研究是势在必行的，笔者主要对注水中悬浮物和油进行了研究。     

下寺湾油田致密油水平井差异化细切割体积压裂工艺优化及矿场试验

为了实现下寺湾油田长8致密油的高效开发,通过开展单轴压缩实验、三轴抗压实验、应力敏感实验和拉伸破裂实验等岩心压裂物理实验,从黏土含量、泊松比、杨氏模量、岩石脆性、水平地应力差异和天然微裂隙发育等方面,对研究区长8致密油体积压裂适应性进行评价。与国内外各大油田致密油(页岩油)相关评价参数对比结果表明,研究区长8致密油藏具备体积压裂的条件。在此基础上,采用模糊综合评价方法对水平段储层进行分类评价,建立水平井水平段“甜点”分类评价标准。创新差异化细切割多簇裂缝设计和缝控体积压裂参数优化方法,形成“多簇射孔、大液量、大排量、低砂比、脉冲式加砂、多尺度支撑剂”的致密油长水平段差异化细切割缝控体积压裂开发技术。先导试验效果显著,初期日产油20.0t以上,第一年累产油3100t,较优化前提升了1380t。     

Q区块聚合物驱不同砂体叠置模式井组调整方法

砂体之间的垂向叠置模式以及与之相匹配的个性化的注入参数是影响聚驱效果的重要原因。在深入认识大庆长垣一类油层曲流河砂体沉积模式的基础上,充分利用精细地质研究成果,通过测井曲线形态及其所反应的旋回特征,对不同沉积单元的砂体垂向叠置模式关系进行研究,将典型区块划分为独立型、下切型、砂泥交互型和单一型4种砂体垂向叠置模式,通过研究不同砂体的沉积特性、渗透率分布特征,结合不同聚合物浓度与渗透率匹配关系图版,个性化设计单井注入参数,提高油层匹配率,改善油层动用状况,形成了不同砂体垂向叠置模式井组单井注入参数个性化设计方法和调整思路,取得了较好的开发效果。注入参数与油层匹配率达到95%以上,油层动用程度达到80%以上,含水最大降幅达到12个百分点以上,低值期长达21个月,提高采收率10个百分点以上,对比分类曲线达到C类标准。该方法对改善聚驱开发效果具有一定的借鉴意义。     

乳状液体系在油田中的应用综述

乳状液体系凭借其特殊的物理化学性能,在油田开发中得到广泛应用,形成了乳化钻井液、乳化酸、乳化压裂液、乳化稠油堵水剂、多重乳状液延缓交联、微乳液、乳化驱油等体系。其中,乳化钻井液体系具有井壁稳定性强、润滑性好和保护油层等优点。乳化酸适用于低渗透碳酸盐岩油气藏的深度酸化改造和强化增产作业,滤失量小,缓速性能好,能进入地层深部。乳化压裂液分为水包油型和油包水型两种,水包油型乳化压裂液具有比油包水型摩阻小、流变性便于调节、易返排等优点;油包水型乳化压裂液与油基冻胶压裂液相比,性价比高,适合于水敏性、低压、低渗储层的压裂改造,具有增黏能力强、黏度调节便利、高携砂、低滤失、低残渣等优点。乳化稠油堵水剂分为活性稠油堵水剂和水包稠油堵水剂,前者注入油井的堵剂为加有适量油包水乳化剂的高黏度稠油;后者是用水包油型乳化剂将稠油乳化在水中制成。乳状液可有效降低地层中的残余油含量,从而提高采收率。多重乳状液体系一般为W/O/W型,由于破乳时间较长,达到了延缓交联的目的;微乳液是指具有超低界面张力、热力学稳定的乳状液。三次采油中,在水中加入表面活性剂和部分高分子化合物,配成驱油溶液进行驱油,可显著提高原油采收率。     

岩石粗糙裂隙渗流试验模型研究

分析岩石裂隙渗流对评价岩体工程安全性有重要意义。通过三维结构光学扫描仪扫描岩石裂隙表面测得三维坐标点并可视化重构，采用节理粗糙度系数和形貌统计等参数定量描述岩石裂隙粗糙程度和起伏特征。试验研究发现，当增大渗透压力梯度时，岩石裂隙渗流将由线性渗流转变为非线性渗流，采用Forchheimer公式能较好拟合这一过程。引入非线性因子E,求得临界非线性流的阈值和雷诺数。引入动量相对损失量—欧拉数来描述裂隙渗流过程中的流体能量演化规律，发现欧拉数呈先急速下降后逐渐趋于稳定的趋势。研究成果对实际工程具有一定指导意义。     

珠江口盆地陆丰地区滨岸储层构型精细解剖

珠江口盆地陆丰油区珠江组储层多为砂体稳定连续分布的滨岸沉积,该区的油田从储层沉积特征、油藏类型、宏观储层物性到微观孔隙结构特征都具有很大的相似性,但开发效果与采收率却有很大区别。以已开发的老油田陆丰A(采收率高达69.8%)和已结算陆丰B油田(采收率为37.8%)为例,结合国内外滨岸储层露头研究成果,分析了该类油田的顶面微构造、隔夹层分布特征等,总结了陆丰地区滨岸储层的构型模式,指出它们在沉积背景与物性等储层特征上虽然具有相似性,但夹层发育模式不同却用相似的开采方案是造成它们采收率差异的主要原因;对于沿岸砂坝发育平行状夹层的油藏,用水平井开发可以有效防止底水锥进,但是对于斜交状夹层发育模式的沿岸砂坝油藏,需要准确预测夹层发育位置,用水平井与定向井结合的方式开采才可以有效提高油田采收率。     

CO2混相压裂液提高采收率作用机理实验研究

柳1断块为低渗透油藏,呈现出采出程度低、采油速度低、水驱动用程度低的“三低”开发特征。为改善柳1断块的开发效果,开展CO₂混相压裂吞吐提高采收率矿场试验。为了明确CO₂混相压裂液提高采收率作用机理及主控因素,以室内实验为手段,开展高温高压条件下CO₂混相压裂液岩心驱替实验。利用高温高压长岩心驱替装置,进行储层渗透率、储层非均质性、原油黏度和不同压裂液添加剂等条件下的CO₂混相压裂液驱油效率实验,分析对比不同影响因素下的驱油效率规律,明确CO₂混相压裂液提高采收率的作用机制并分析主控因素。实验结果表明,储层渗透率、储层非均质性和不同压裂液添加剂等条件对储层提高采收率具有不同程度的影响,提高采收率的主控因素为添加剂的种类和渗透率,其中CO₂+增溶剂的驱油效率最好,提高储层渗透率可以有效提高CO₂+添加剂的驱油效率。在柳1断块稠油油藏开展CO₂混相压裂技术矿场试验,措施有效率100%,阶段增油10140t。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Contents in Volume 23,2014

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Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.