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21.
ú�����������̼���ֵģ�� 总被引:9,自引:2,他引:9
中国煤层气资源丰富 ,据估算 ,埋深 2 0 0 0m以浅的煤层气资源达 (30~ 35 )× 10 12 m3 。但中国煤层气地面开发刚进入起步阶段 ,加之中国煤田地质条件比较复杂 ,因此研究中国特殊地质条件下煤层气的解吸、扩散和渗流机理的具体地质表现是认识煤层气可采性的关键。针对我国煤层气开采的特殊性 ,我国采取“地面开采和井巷抽放相结合”的方针。然而井巷开采占了相当的比例。本文建立了煤层气扩散渗流数学物理方程 ,并对煤层气渗流偏微分方程 ,采用差分法 ,进行了数值模拟计算。模拟结果表明 ,所建立的煤层气扩散渗流模型较准确地反映了煤层中煤层气流动规律 ,模拟后的煤层气压力变化曲线可以确定煤层气的开采压力变化范围和煤层气产气最大面积 ,对我国大面积低渗透性无烟煤煤层气的开发具有指导意义。 相似文献
22.
Solubilization of water and aqueous NaCl in mixed reverse micelles (RMs) comprising sodium bis(2‐ethylhexyl) sulfosuccinate (AOT), and polyoxyethylene (20) sorbitan trioleate or polyoxyethylene (20) sorbitan monooleate has been studied at different compositions (Xnonionic = 0–1.0) at a total surfactant concentration, ST = 0.10 × 103 mol m?3 in biocompatible oils of different chemical structures; viz., ethyl oleate (EO), isopropyl myristate (IPM) and isopropyl palmitate (IPP) at 303 K. The enhancement in water solubilization (i.e., synergism) has been evidenced by the addition of nonionic surfactant to dioctyl sulfosuccinate/oil(s)/water systems. Addition of NaCl in these systems at different Xnonionic enhances their solubilization capacities further until a maximum, ωNaCl,max is reached. ωNaCl,max and [NaCl]max (concentration at which maximization of NaCl solubilization occurs) depend on type of nonionic surfactant, its content (Xnonionic) and oil. A new solubilization efficiency parameter (SP*water or SP*NaCl) has been proposed to compare solubilization phenomena in these oils. The energetic parameters of the desolubilization process of water or aqueous NaCl in single and mixed RMs have been estimated. Energetically, the water dissolution process in oil has been found to be more exothermic as well as more organized in IPP. Overall, the dissolution of water and aqueous NaCl in mixed RMs is entropically driven process. Conductance behavior of these systems in the presence of NaCl has been investigated under different [NaCl] at 303 K. An attempt has been made to give an insight to the mechanism of solubilization phenomena, percolation in conductance and microstructures vis‐à‐vis role of biocompatible oils in these systems. 相似文献
23.
王建国 《深圳大学学报(理工版)》1990,(Z1)
本文介绍了研究无规凝聚体系的重要理论工具——分形及渗流理论的基本原理,并举例分析评述了分形及渗流在材料科学中的应用. 相似文献
24.
油井酸压后三维渗流动态预测 总被引:5,自引:0,他引:5
本文综述考虑了影响酸压裂缝导流能力的诸因素:生产压降变化、非达西效应、油藏污染、裂缝几何尺寸、和导流能力沿缝变化等;推导并建立了三维酸压油井生产动态预测模型。 相似文献
25.
26.
Let P be a realization of a homogeneous Poisson point process in ℝ
d
with density 1. We prove that there exists a constant k
d
, 1<k
d
<∞, such that the k-nearest neighborhood graph of P has an infinite connected component with probability 1 when k≥k
d
. In particular, we prove that k
2≤213. Our analysis establishes and exploits a close connection between the k-nearest neighborhood graphs of a Poisson point set and classical percolation theory. We give simulation results which suggest
k
2=3. We also obtain similar results for finite random point sets.
Part of the work was done while S.-H. Teng was at Xerox Palo Alto Research Center and MIT.
The work of F.F. Yao was supported in part by a grant from the Research Grants Council of the Hong Kong Special Administrative
Region, China [Project No. CityU 1165/04E]. 相似文献
27.
The charge transport in organic semiconductors has been investigated theoritically. A n analytical model describing the hopping
current is developed. This model is based on VRH (variable range hopping) theory and percolation theory. The results of calculation
are compared to the prediction of Mott’s formalism, which has been widely used to describe hopping transport in amorphous
semiconductors. The model is also found to be in good agreement with recent experimental data. 相似文献
28.
Characterization of the granular packing and percolation threshold of reactive powder concrete 总被引:4,自引:0,他引:4
Olivier Bonneau Christian Vernet Micheline Moranville Pierre-Claude Aïtcin 《Cement and Concrete Research》2000,30(12):1861-1867
Reactive powder concrete (RPC) is a new cement-based material developed through microstructural engineering. RPC is composed of very fine powders: sand, crushed quartz and silica fume, all with particle sizes comprised between 300 and 0.02 μm, and a low water content, W/C<0.20. A very dense matrix is achieved by optimizing the granular packing of these powders. This compactness confers to RPC ultrahigh strength and durability.where Av depends on the nature and the dosage of the different mineral and organic components, and Bv is an invariant related to the granular packing. From 19 different RPC compositions, an average value of 12.1 with a standard deviation of 1.7 were found for Bv. The capillary porosity percolation threshold was also deduced from this relationship. It has been found that when the degree of hydration is equal to 26%, the capillary pore space is discontinuous. This last result is in agreement with the prediction of the NIST microstructural model by Bentz and Garboczi [D., Bentz, E. Garboczi, Percolation of phases in a three-dimensional cement paste microstructural model, Cem Concr Res 21 (2) (1991) 325–344]. A continuous determination of the degree of hydration based on electrical conductivity is proposed. 相似文献
The hydration kinetic of the cementitious matrix using electrical conductivity and isothermal calorimetry is presented. A linear relationship between the logarithm of conductivity ln(σ) and the degree of hydration , has been found:
ln(σ)=Av−Bv
29.
30.
Rheological properties of the system gelatin + water at a polymer concentration of 5.0% by wt at a temperature of 301 K and
an angular frequency of 0.628 rads–1 are presented and evaluated by use of the percolation theory. A frequency power law has been found close to the gel point
from which a critical time range could be deduced in which the powers of the loss and storage modulus are the same. The times
needed for the gelation from the percolation relations are close to the range where the exponents of the frequency power law
relations are identical. The scaling coefficient Δ for physical gelation agrees very well with that found for chemical gelation
by Durand and coworkers.
Received: 9 October 2000 / Reviewed and accepted: 10 October 2000 相似文献