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81.
Colin M. Sayers 《Transport in Porous Media》1991,6(3):331-336
The model of Snow, in which a fracture is represented by two parallel channel walls, has frequently been used to study the flow of fluid in fractured reservoirs. Although this model gives important insight into the flow in fractures, very few naturally occurring fractures have smooth parallel faces. In this paper, a simple model of partially contacting and en-echelon fractures frequently found in geological materials is presented. In this model, a fracture is viewed as a planar region where separation and contact zones both exist. To analyse the fluid flow in a porous medium containing fractures of this type, a planar array of periodically spaced fracture segments is analysed. The flow through a single fracture is deduced by taking the limit as the spacing between neighbouring fractures becomes large. The hydraulic conductivity parallel to the fractures is found to be the parallel combination of the conductivity of the porous matrix and the system of parallel fractures, the individual fracture conductance being a series combination of the hydraulic conductance of the separation and contact zones. This interpretation enables the conductance of the contact zones to be evaluated and the results to be generalised to the case in which the material in the contact regions has a hydraulic conductivity different to that of the matrix. This may arise, for example, from grain-size reduction during fracturing or may result from a partial mineralisation or cementation of the fracture. 相似文献
82.
The matrix-fracture transfer shape factor is one of the important parameters in modeling naturally fractured reservoirs. Four
decades after Warren and Root (1963, SPEJ, 245–255.) introduced the double porosity concept and suggested a relation for it, this parameter is still not completely
understood. Even for a single-phase flow problem, investigators report different shape factors. This study shows that for
a single-phase flow in a particular matrix block, the shape factor that Warren and Root defined is not unique and depends
on the pressure in the fracture and how it changes with time. We use the Laplace domain analytical solutions of the diffusivity
equation for different geometries and different boundary conditions to show that the shape factor depends on the fracture
pressure change with time. In particular, by imposing a constant fracture pressure as it is typically done, one obtains the
shape factor that Lim and Aziz (1995, J. Petrolean Sci. Eng. 13, 169.) calculated. However, other shape factors, similar to those reported in other studies are obtained, when other boundary
conditions are chosen. Although, the time variability of the boundary conditions can be accounted for by the Duhamel’s theorem,
in practice using large time-steps in numerical simulations can potentially introduce large errors in simulation results.
However, numerical simulation models make use of a stepwise approximation of this theorem. It is shown in this paper that
this approximation could lead to large errors in matrix-fracture transfer rate if large time-steps are chosen. 相似文献
83.
分形在油气田开发中的应用 总被引:10,自引:1,他引:10
分形用于测井资料分析,为油藏描述提供了新的工具,使得利用油藏数值模拟来模拟复杂结构的油气藏变得更加便利;分形油藏上的试井分析解决了一些以前难以解释的问题;用分形来描述裂缝和孔洞结构,提高了酸化压裂的设计水平;用分形理论来描述两相流,揭示了部分粘性指进的触发机理.总之,分形理论在油气田开发中的应用,促进了渗流力学基础理论的发展. 相似文献
84.
Ghodsieh Moosa Hasankhani Mohammad Madani Feridun Esmaeilzadeh Dariush Mowla 《Journal of Dispersion Science and Technology》2013,34(12):1780-1789
AbstractWater injection as one of the most efficient and worldwide extensively employed approach in homogenous oil reservoirs suffers from early water breakthrough time as well as low oil sweep efficiency values in fractured oil reservoirs. This study investigates the potential application of Cr(III)-acetate based gel polymer system in a typical water injection process using one fractured micromodel. For this purpose, three sulfonated polyacrylamides, different in solfunation degree, and one hydrolyzed polyacrylamide were studied regarding gelation time, gel strength and stability to find the optimized conditions in terms of polymer type and concentration, and polymer/Cr(III)-acetate ratio, which were subsequently used for one dynamic test. Results illustrated the optimized conditions as AN 105 polymer with concentration of 5000?ppm and polymer/Cr(III) ratio of 5. Moreover, results showed that implementing such gel system yields an increased oil recovery value of 24.46% OOIP at 1.55 PV and delays the breakthrough time from 0.47 PV to 0.51 PV. 相似文献
85.
ChunMei Yao ZhiHua Chen ZhiHao Ma Simone Severini Alessio Serafini 《中国科学:物理学 力学 天文学(英文版)》2014,57(9):1703-1711
The uncertainty principle is a crucial aspect of quantum mechanics.It has been shown that quantum entanglement as well as more general notions of correlations,such as quantum discord,can relax or tighten the entropic uncertainty relation in the presence of an ancillary system.We explored the behaviour of entropic uncertainty relations for system of two qubits—one of which subjects to several forms of independent quantum noise,in both Markovian and non-Markovian regimes.The uncertainties and their lower bounds,identified by the entropic uncertainty relations,increase under independent local unital Markovian noisy channels,but they may decrease under non-unital channels.The behaviour of the uncertainties(and lower bounds)exhibit periodical oscillations due to correlation dynamics under independent non-Markovian reservoirs.In addition,we compare different entropic uncertainty relations in several special cases and find that discord-tightened entropic uncertainty relations offer in general a better estimate of the uncertainties in play. 相似文献
86.
S. A. Soliman G. S. Christensen M. A. Abdel-Halim 《Journal of Optimization Theory and Applications》1986,49(3):449-461
The optimal monthly operating policy of a multireservoir hydroelectric power system is a stochastic nonlinear problem. This paper presents a new method for determining the optimal monthly operating policy of a power system ofn reservoirs in series on a river taking into account the stochasticity of the river flows. Functional optimization techniques and minimum-norm formulation have been used to find the optimal release policy of the system. Results for a numerical example composed of four reservoirs are presented.This work was supported by the National Research Council of Canada, Grant No. A4146. 相似文献
87.
We present in this paper a new method for solving the optimization problem of a variable head multireservoir power system under a critical water condition for long-term regulation. The problem is formulated as a minimum norm problem. The proposed method is efficient in computing time and in calculating the expected benefits from the system during the critical period. Numerical results are presented for a real system in operation consisting of two rivers; each river has two reservoirs connected in a series.This work was supported by the National Research Council of Canada, Grant No. A4146. The authors wish to thank B. C. Hydro for providing the reservoir data. 相似文献
88.
89.
Johannes A. C. Barth Michael Mader Franziska Nenning Robert van Geldern Kurt Friese 《Isotopes in environmental and health studies》2017,53(4):413-426
The aim of this study was to identify sources of carbon turnover using stable isotope mass balances. For this purpose, two pre-reservoirs in the Harz Mountains (Germany) were investigated for their dissolved and particulate carbon contents (dissolved inorganic carbon (DIC), dissolved organic carbon, particulate organic carbon) together with their stable carbon isotope ratios. DIC concentration depth profiles from March 2012 had an average of 0.33 mmol L–1. Increases in DIC concentrations later on in the year often corresponded with decreases in its carbon isotope composition (δ13CDIC) with the most negative value of –18.4?‰ in September. This led to a carbon isotope mass balance with carbon isotope inputs of ?28.5?‰ from DOC and ?23.4, ?31.8 and ?30.7?‰ from algae, terrestrial and sedimentary matter, respectively. Best matches between calculated and measured DIC gains were achieved when using the isotope composition of algae. This shows that this type of organic material is most likely responsible for carbon additions to the DIC pool when its concentrations and δ13CDIC values correlate negatively. The presented isotope mass balance is transferable to other surface water and groundwater systems for quantification of organic matter turnover. 相似文献
90.
提出了一种计算二维有限变形弹塑性摩擦接触问题形状设计灵敏度的算法. 采用主动
集策略和mortar方法处理接触边线上的约束条件. 在mortar接触边线的切线和法线方向上
采用相同的名义罚函数,提出基于名义罚函数的移动摩擦锥算法来正则化接触约束条件,发
展了一种新的二维多体有限变形摩擦接触算法. 在此基础上, 通过将离散形式的摩擦接触问题
控制方程对形状设计变量微分,得到了该路径相关问题的直接微分法解析设计灵敏度
计算格式, 其节点位移灵敏度方程在每个增量步不用迭代、直接求解. 与国际上现有
的二维多体有限变形摩擦接触问题的解析设计灵敏度算法相比,本算法不需分
解为法向和切向推导,表达式较简洁,便于编程实现. 数值算例验证了算法的精度
和有效性. 相似文献