Pionowe zróżnicowanie wodoprzepuszczalności węglanowych skał triasowych w świetle statystycznej analizy wyników prónych pompowań (monoklina śląsko-krakowska)

Abstract

VERTICAL DIFFERENTIATION IN THE WATER PERMEABILITY OF  CARBONATE TRIASSIC ROCKS IN THE LIGHT OF A STATISTICAL ANALYSIS OF THE RESULTS OF PUMPING TESTS (SILESIA-CRACOW MONOCLINE)

Summary

The present paper is based on the results of about 240 pumping tests made in fissured and carst Triassic limestones and dolomites in the mining area of zinc and lead ores, situated to the north-west ofCracow. The results obtained from pumping tests were used for the purpose of calculating water permeability coefficients by means of uniform formulae, which ,corresponded to the hydraulic model of a given borehole during pumping tests. An assumption was made that the flow of the water was steady, laminar, and two-dimensional. These conditions were not fulfilled in some cases. The authors found that the distribution of the logarithms of 'Permeability coefficients was normal (Figs. 2 and 3). The geometric mean (Km) of the population investigated was 6.5 m/s and the standard error (s) – 7.63 m/so An investigation of vertical changes in the permeability coefficient is preceded by a discussion on the importance of the primary and secondary geological processes that might have led to these changes. The characteristic of water permeability in the vertical range was made in two ways. In the first case, the depth of a given part of the Triassic sequence was measured from the bottom of Keuper clays which occur only in a part ,of the area investigated here; in the second case the depth was measured from the surface of the .ground. As a result -of the analysis described here the authors conclude that the mean permeability 'coefficients decrease from the top to the bottom of the carbonate Triassic series, this decreasing tendency being represented by a curve on the corresponding diagrams (Figs. 8, 10). However, these changes are within values of the same order and thus, for the purpose of calculations and analogue modelling, the series concerned can be regarded as homogeneous in vertical range.