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1.
We propose a methodology, called multilevel local–global (MLLG) upscaling, for generating accurate upscaled models of permeabilities
or transmissibilities for flow simulation on adapted grids in heterogeneous subsurface formations. The method generates an
initial adapted grid based on the given fine-scale reservoir heterogeneity and potential flow paths. It then applies local–global
(LG) upscaling for permeability or transmissibility [7], along with adaptivity, in an iterative manner. In each iteration of MLLG, the grid can be adapted where needed to reduce
flow solver and upscaling errors. The adaptivity is controlled with a flow-based indicator. The iterative process is continued
until consistency between the global solve on the adapted grid and the local solves is obtained. While each application of
LG upscaling is also an iterative process, this inner iteration generally takes only one or two iterations to converge. Furthermore,
the number of outer iterations is bounded above, and hence, the computational costs of this approach are low. We design a
new flow-based weighting of transmissibility values in LG upscaling that significantly improves the accuracy of LG and MLLG
over traditional local transmissibility calculations. For highly heterogeneous (e.g., channelized) systems, the integration
of grid adaptivity and LG upscaling is shown to consistently provide more accurate coarse-scale models for global flow, relative
to reference fine-scale results, than do existing upscaling techniques applied to uniform grids of similar densities. Another
attractive property of the integration of upscaling and adaptivity is that process dependency is strongly reduced, that is,
the approach computes accurate global flow results also for flows driven by boundary conditions different from the generic
boundary conditions used to compute the upscaled parameters. The method is demonstrated on Cartesian cell-based anisotropic
refinement (CCAR) grids, but it can be applied to other adaptation strategies for structured grids and extended to unstructured
grids. 相似文献
2.
James V. Lambers Margot G. Gerritsen Bradley T. Mallison 《Computational Geosciences》2008,12(3):399-416
We propose a new single-phase local upscaling method that uses spatially varying multipoint transmissibility calculations.
The method is demonstrated on two-dimensional Cartesian and adaptive Cartesian grids. For each cell face in the coarse upscaled
grid, we create a local fine grid region surrounding the face on which we solve two generic local flow problems. The multipoint
stencils used to calculate the fluxes across coarse grid cell faces involve the six neighboring pressure values. They are
required to honor the two generic flow problems. The remaining degrees of freedom are used to maximize compactness and to
ensure that the flux approximation is as close as possible to being two-point. The resulting multipoint flux approximations
are spatially varying (a subset of the six neighbors is adaptively chosen) and reduce to two-point expressions in cases without
full-tensor anisotropy. Numerical tests show that the method significantly improves upscaling accuracy as compared to commonly
used local methods and also compares favorably with a local–global upscaling method. 相似文献
3.
一种测求水井含水层导水系数的新方法 总被引:1,自引:0,他引:1
本文给出了一种测求水井含水层导水系数的新方法。利用Cooper理论和振动理论,通过简单的试验,可以测求出水井含水层的导水系数。用这种方法计算出珍珠泉井含水层的导水系数为2439m~2/d,用抽水试验法测得该系数为2618m~2/d,两者符合得较好。 相似文献
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Subsurface flow models can exhibit strong full-tensor anisotropy due to either permeability or grid nonorthogonality effects.
Upscaling procedures, for example, generate full-tensor effects on the coarse scale even for cases in which the underlying
fine-scale permeability is isotropic. A multipoint flux approximation (MPFA) is often needed to accurately simulate flow for
such systems. In this paper, we present and apply a different approach, nonlinear two-point flux approximation (NTPFA), for
modeling systems with full-tensor effects. In NTPFA, transmissibility (which provides interblock connections) is determined
from reference global flux and pressure fields for a specific flow problem. These fields can be generated using either fully
resolved or approximate global simulations. The use of fully resolved simulations leads to an NTPFA method that corresponds
to global upscaling procedures, while the use of approximate simulations gives a method corresponding to recently developed
local–global techniques. For both approaches, NTPFA algorithms applicable to both single-scale full-tensor permeability systems
and two-scale systems are described. A unified framework is introduced, which enables single-scale and two-scale problems
to be viewed in a consistent manner. Extensive numerical results demonstrate that the global and local–global NTPFA techniques
provide accurate flow predictions over wide parameter ranges for both single-scale and two-scale systems, though the global
procedure is more accurate overall. The applicability of NTPFA to the simulation of two-phase flow in upscaled models is also
demonstrated. 相似文献
7.
以新疆三工河流域浅层含水层为研究对象,采用地质统计学中的原理与方法,初步分析了该含水层导水系数的空间分布特征.结果表明,1)该含水层导水系数在空间上的变化服从正态概率分布;2)含水层的导水性能在空间上属于中等变异性;3)导水系数在空间位置的一定范围内具有相关性,东西方向的相关尺度a=5.0km,南北方向的相关尺度a=7.8km;4)该含水层的导水性能为各向异性的.文中的研究方法与步骤可以用来分析其它冲洪积浅层含水层导水系数的空间分布特征. 相似文献
8.
中国食管癌与土壤环境中元素的相关性 总被引:1,自引:0,他引:1
利用土壤元素资料 2 0 6 94 4 8个数据 ,食管癌死亡调查资料 1750 80例 ,研究了食管癌死亡率与人群生存的土壤环境中元素的相关性。结果表明 ,铅、硒、铷、铯、镁、钙、镓、铊、钍、铀、锡、铪、铋、钼、溴、碘元素与食管癌死亡率有相关性 相似文献
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井水位的“记忆”滞后效应 总被引:5,自引:0,他引:5
观测资料表明,井水位对信息响应存在的“记忆”滞后现象,它与一般的位相滞后不同,在鲁29井现场试验也证明了井水位对井吕空气压力变化的响应存在的“记忆”滞后现象。利用水平层状承压含水层模式,从理论上解释了井水位对井口空气压力变化响应“记忆”滞后现象,认为这种现象与水井含水层的导水系数有关,含水层导不系数越小,这种现象越明显,用一般多元回归方法无法较好地扣除井水位中“记忆”滞后影响,作给出了一种可以扣 相似文献