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1.
考虑油藏储层参数变化的数值模拟研究   总被引:3,自引:1,他引:2  
油田在注水开发过程中,储层的物性参数、流体性质等都在不断发生变化,本文根据胜坨油田沙二1-2的储层参数随含水变化的基本规律,对黑油模型数值模拟软件进行了改进,使之能够考虑油藏储层参数的变化,并应用软件分析了参数变化对开发效果的影响。改进后的软件提高了数值模拟精度,使计算结果更能真实的反映地下流体分布情况,为改善油藏的开发效果,采取有针对性的开发措施,提供了重要依据。  相似文献   

2.
离散裂缝网络模型主要从裂缝的几何形状以及流动机理上对裂缝进行表征和描述,可以比较精确地描述裂缝特征及油藏的非均质性。该文结合油藏边界及裂缝的真实分布状态,将油藏划分为若干子区域,在每个子区域上布网格节点进行Delaunary三角剖分与Vornoni网格剖分,得到了PEBI网格。为了满足质量守恒,利用有限体积法进行了求解,对网格域和计算域之间的误差进行了修正。结合离散裂缝的数学模型及传导率计算法则,实现了高精度的离散裂缝油藏数值模拟,研究了大裂缝的分布、长短、与注采井的贯穿状况等因素对水驱油的推进方向、速度、见水时间、采出程度的影响规律。结果表明PEBI网格能准确地表征裂缝特征,再现裂缝的分布,正确地模拟裂缝影响下的水驱开发规律。  相似文献   

3.
为了认识低渗透油藏的水驱动态规律,完善低速非达西渗流的水驱动态理论,该文基于流管法的基本原理,给出了五点法井网的三角流管模型,引入启动压力梯度,建立了低渗透油藏水驱动态开发指标的油藏工程计算方法。经对比验证,利用该方法计算的产油量与实际产量一致,若不考虑启动压力梯度会导致产油量偏高,存在较大误差。绘制并分析了渗流阻力、含水饱和度、产油量、产水量、采出程度以及波及系数等动态指标的变化曲线。结果表明,随着注入水从主流管向外的扩展,水驱前缘推进变慢,渗流阻力也随之变大,流管中注入水突破变慢。主流管突破后产油量迅速下降,开始迅速产水,采出程度和波及系数增幅变缓。所有流管都突破后产量和采出程度趋于平缓,注入水完全波及。同一时刻水驱前缘后从注入井端到采油井端的含水饱和度不断减小。研究结果可为低渗透油田水驱开发及动态分析提供指导。  相似文献   

4.
低渗透油藏非线性渗流理论及数值模拟方法   总被引:3,自引:0,他引:3  
针对低渗透油藏非线性渗流理论与数值模拟方法方面存在的大量问题,从毛细管模型出发,推导了低渗透油藏非线性渗流新模型,详细解释了新模型中特有的物理参数内涵;并由此建立了低渗透油藏非线性单相渗流理论,与相对渗透率引入渠道流假设一致,将单相非线性新模型推广到两相渗流中,建立了能够同时考虑启动压力梯度、非线性渗流弯曲段连续变化的数值模拟方法。根据所建立的低渗透油藏单相稳态和非稳态渗流理论以及数值模拟方法,开展了达西、拟启动压力梯度和非线性模型的油藏动态对比计算。结果表明:低渗透油藏主要受非线性渗流控制,仅井点的少数网格存在拟线性流动,非线性模型计算的结果介于达西和拟启动线性模型之间。  相似文献   

5.
聚合物驱相对渗透率曲线及影响因素试验研究   总被引:3,自引:0,他引:3  
本文从聚合物溶液在多孔介质中流动的特点出发,在考虑渗率降低系数和多孔介质中流变特性的基础上,建立了聚合物驱相对渗透率计算方法,利用驱替试验数据,用本文方法和不考虑多孔介质中流变性两种方法分别计算出聚合物驱相对渗透率。分析研究了水驱与聚合物驱相对渗透率曲线的差异。研究了多孔介质中剪切速率对计算的影响以及聚合物浓度。注入速度对聚合物驱相对渗透率的影响。  相似文献   

6.
氮气泡沫热力驱数值模拟研究   总被引:3,自引:1,他引:2  
建立了三维、三相、多组分数学模型,模型考虑了相平衡以及温度、界面张力对油、气、水三相渗流的影响以及起泡剂损失的各种机理,较全面地反映了氮气泡沫热力驱的作用机理。采用模块化的程序设计方法,编制了三维、三相、多组分氮气泡沫热力驱油藏数值模拟软件。利用该数值模拟软件对氮气泡沫热力驱进行了数值模拟,讨论了注采参数及起泡剂性质参数对采油效果的影响。  相似文献   

7.
低渗透油藏中水平井两相渗流分析   总被引:14,自引:6,他引:8  
大量实验表明,在低渗透多孔介质中,渗流不再符合线性达西定律,而具有启动压力梯度,本文从Buckley-Leverret不混溶两相渗流驱替理论出发,考虑启动压力梯度的影响,对水平井两相渗流进行分析,得到了椭球形边水油藏中水平井定产时的压力分布公式和定压生产时的产量公式,以及饱和度分布公式。经图示分析得出结论:启动压力梯度不仅增大油藏的生产压差,而且使油藏的无水采收率和水驱采收率减少;增大注入量可以降低启动压力梯度对两相渗流的不利影响,从而提高水驱采收率,因此开发含启动压力梯度油藏,应小井距,大流量,大压差进行注水开发;水平井的两相渗流解析解为数值模拟中水平井的处理提供很好的方法。  相似文献   

8.
低渗透裂缝油藏渗吸法采油数值模拟理论研究   总被引:8,自引:1,他引:7  
根据低渗透裂缝油藏渗吸法采油渗流机理,建立了双孔双渗渗吸法采油数学模型,并给出了数值解法和流动系数的取值方法。通过实例验证。该方法计算的含水率指标与矿场实际值符合程度较高。在此基础上,定量分析了渗吸法采油的主要影响因素,结论是:裂缝与基质渗透率比大于100,裂缝密度大于0.030条/m,油水粘度比小于15,毛管力较大的水湿油藏适合渗吸法采油,能够提高水驱采收率1%以上。  相似文献   

9.
变形介质油藏中的不稳定渗流   总被引:5,自引:0,他引:5  
大量实验表明:当油藏生产原油时,随着地层中流体压力的降低,油层的孔隙度和渗透率下降,特别是在异常高压油藏中尤为显著。数据表明多孔介质的孔隙度和渗透率随压降的变化规律是指数关系,而实际的油藏介质变形是弹塑性的,即变形在流体压力恢复后,变形不可能完全恢复,因此在开发前期一定要注意保持一定的地层压力。从流体和多孔介质的本构方程出发,建立液体在变形介质油藏中渗流的微分方程。用解析的方法得到了变形介质中的定常流动的精确解;并用数值模拟的方法,研究了无限大油藏、封闭油藏和边水油藏中的不稳定压力,绘制了相应的井底压力曲线。最后分析了封闭变形介质油藏中,定压生产时,油井的产量变化。研究表明:在异常高压的油藏中,必须考虑由介质变形引起的孔隙度和渗透率的影响。  相似文献   

10.
低渗透油藏毛细管压力动态效应的数值模拟研究   总被引:1,自引:0,他引:1  
实验分析和理论研究表明毛细管压力存在动态效应,即其与润湿相流体的饱和度变化率相关,已有的物理实验表明低渗透油藏中的毛细管压力动态效应对于油气渗流存在着较大的影响。该文首先根据23个低渗岩心渗流曲线的数值拟合分析结果,建立了各项物理意义明确的非线性渗流运动方程,然后通过构造三种不同的饱和度变化速率的润湿相流体饱和度时变曲线,利用有限元数值方法模拟了三种饱和度曲线对应下的一维水驱油过程,并在完全基于数学方法较少依赖于物理实验的基础上计算了毛细管压力曲线。数值模拟的结果表明,低渗透油藏中存在较为明显的毛细管压力动态效应,且动态系数与介质的固有渗透率负相关,与润湿相流体的黏滞系数正相关。并通过与达西线性渗流模拟结果的对比表明了低渗油藏中非线性渗流产生的毛细管压力动态效应更为明显,动态系数也更大。  相似文献   

11.
Call for Papers     
正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.  相似文献   

12.
根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。  相似文献   

13.
The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L?1, the median total phosphorus was 0.29 mg L?1 and the median total nitrogen was 1.56 mg L?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.  相似文献   

14.
Carbon dioxide (CO2) and methane (CH4) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO2 and CH4 diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 106 t CO2eq km2 per year, or 24 × 106 t CO2eq per year. This corresponds to a plant emission factor of 3.18 kg CO2eq MWh?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO2eq per year, or 5.83 kg CO2eq MWh?1, which is in the lower range of the studied reservoirs.  相似文献   

15.
The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.  相似文献   

16.
为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。  相似文献   

17.
Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.  相似文献   

18.
River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.  相似文献   

19.
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).  相似文献   

20.
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.  相似文献   

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