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991.
A. J. Desbarats 《Mathematical Geology》1994,26(1):1-21
Steady-state radial flow in three-dimensional heterogeneous media is investigated using a geostatistical approach. The goal of the study is to develop a model of the relationship between corescale hydraulic conductivities measured at the wellbore and the conductivity of the surrounding drainage region as measured by a larger scale flow experiment such as a pump test. Conductivity at the point or core-scale is modeled as a stationary and multivariate lognormal spatial random function. Conductivity of the drainage region is obtained by a weighted nonlinear spatial average over the point-scale values within. This empirical spatial averaging process is shown to yield excellent approximations of true effective drainage region conductivities calculated using a numerical flow model. The geostatistical model for point-scale conductivity and the spatial averaging process are used to determine the first and second order ensemble moments of drainage region conductivity. In particular, an expression is derived for the conditional expectation of drainage region conductivity given point-scale values measured at the wellbore. The results are illustrated in a case study of a well from a sandstone oil reservoir where both core and transient-test conductivity data from the same interval are available for comparison. 相似文献
992.
993.
Fractal geostatistics are being applied to subsurface geological data as a way of predicting the spatial distribution of hydrocarbon reservoir properties. The fractal dimension is the controlling parameter in stochastic methods to produce random fields of porosity and permeability. Rescaled range (R/S)analysis has become a popular way of estimating the fractal dimension, via determination of the Hurst exponent (H). A systematic investigation has been undertaken of the bias to be expected due to a range of factors commonly inherent in borehole data, particularly downhole wireline logs. The results are integrated with a review of previous work in this area. Small datasets. overlapping samples, drift and nonstationariry of means can produce a very large bias, and convergence of estimates of H around 0.85–0.90 regardless of original fractal dimension. Nonstationarity can also account for H>1, which has been reported in the literature but which is theoretically impossible for fractal time series. These results call into question the validity of fractal stochastic models built using fractal dimensions estimated with the R/Smethod. 相似文献
994.
Dae S. Young 《Mathematical Geology》1987,19(6):467-479
Geostatistics is extended to the spatial analysis of vector variables by defining the estimation variance and vector variogram in terms of the magnitude of difference vectors. Many random variables in geotechnology are in vectorial terms rather than scalars, and its structural analysis requires those sample variable interpolations to construct and characterize structural models. A better local estimator will result in greater quality of input models; geostatistics can provide such estimators: kriging estimators. The efficiency of geostatistics for vector variables is demonstrated in a case study of rock joint orientations in geological formations. The positive cross-validation encourages application of geostatistics to spatial analysis of random vectors in geoscience as well as various geotechnical fields including optimum site characterization, rock mechanics for mining and civil structures, cavability analysis of block cavings, petroleum engineering, and hydrologic and hydraulic modelings. 相似文献
995.
Indicator cokriging is an alternative to disjunctive kriging for estimation of spatial distributions. One way to determine which of these techniques is more accurate for estimation of spatial distributions is to apply each to a particular type of data. A procedure is developed for evaluation of disjunctive kriging and indicator cokriging for such an application. Application of this procedure to earthquake ground motion data found disjunctive kriging to be at least as accurate as indicator cokriging for estimation of spatial distributions of peak horizontal acceleration. Indicator cokriging was superior for all other types of earthquake ground motion data. 相似文献
996.
Xinxian Lu 《中国地理科学(英文版)》1992,2(3):256-265
The developed regions are faced with the problems of regional comprehensive development, and the research on regional comprehensive
development has become a trend in the world. To optimize regional industrial structure and to select and determine scientifically
the spatial development strategy of regional industries are the central themes to be solved for the research on regional comprehensive
development in the developed regions. This paper proposed the basis for optimizing regional industrial structure, and the
main factors of selecting and determining the regional leading industries. Based on this, the paper puts forward the leading
industries and the spatial development strategy in Shanghai-Nanjing-Hangzhou area in the future ten or more years. Combined
with the situation of Shanghai-Nanjing-Hangzhou area, the paper also discusses some problems of locating superior developing
axis to benefit the rational distribution of regional productive forces. 相似文献
997.
998.
Since Berry argued in 1976 that counterurbanization had replaced urbanization in the U.S., a debate has ensued as to whether the phenomenon also exists in Western Europe. Proponents of a developmental theory of counterurbanization contend that the phenomenon should be evident in countries which have achieved a very high level of socioeconomic development, including the Federal Republic of Germany (FRG). Most of the German and English language literature on the topic suggests the contrary for the FRG. Here urbanization and counterurbanization are restricted to specific geographic meanings, i.e., spatial agglomeration and deglomeration. Results from four interrelated tests show a trend toward counterurbanization evident as early as the 1960s in the post-war regional demographic data of the FRG. 相似文献
999.
《The Professional geographer》1986,38(1):101-104
Geographic Software Reviewed in this article: THE DIFFUSION GAME . Christopher J. Lovelock and Charles B. Weinberg . MAPIT . Raymond J. Kalush , Jr . SIMODEL . Peter A. Williams and A. Stewart Fotheringham . WEATHER FRONTS . P. C. Moyer . WORLD DYNAMICS . Mark Lewis Baldwin 相似文献
1000.
Morgan N. Hardwick-Witman Arthur C. Mathieson 《Estuarine, Coastal and Shelf Science》1983,16(2):113-129
Quantitative sampling of the dominant intertidal epibiota was conducted seasonally along an estuarine gradient within the Great Bay Estuary System, New Hampshire, U.S.A. The abundance and zonation of the dominant macroorganisms varied with distance into the estuary. Replacement of marine by estuarine species occurred, and overall abundance and species richness decreased along the estuarine gradient. Zonation patterns within the inner estuary were primarily allied with substrata. Maximum abundance of invertebrates occurred in the mid-intertidal zone where a dense fucoid canopy provided habitat heterogeneity. Densities of epibiotic organisms decreased toward low water, especially in the inner estuary where hard substratum was limiting. Settlement blocks, introduced into the low intertidal zone, were dominated by barnacles and fucoid algae; after 16 months, the species composition on the settlement blocks resembled the adjacent community. Semibalanus balanoides settled in the spring, while Fucus vesiculosus var. spiralis exhibited low but constant settlement. Despite the physical rigors of the estuarine environment, only Semibalanus balanoides, Ilyanassa obsoleta and Spartina alterniflora showed significant seasonal changes in density. Thus, there are predictable and persistent epibiotic species assemblages within the intertidal zone of the Great Bay Estuary System. 相似文献