HOMOGENEITY VERSUS HETEROGENEITY OF SELECTED PARAMETERS OF COAL SEAMS - THE LUBLIN COAL BASIN CASE STUDY, POLAND

The Lublin Coal Basin (LCB) is located in the central-eastern part of Poland. Within the basin, 11 bituminous coal deposits were discovered and assessed in the Lower Carboniferous Lublin Beds over an area of about 1,200 km(2). The Carboniferous succession is covered by overburden, several hundreds of meters thick. According to the assessment report, average thickness of mineable coal seams is 1.5-1.6 m. Particular seams show complicated internal structure, i.e., significant changes of thickness, common (1-4) intercalations of barren rocks, seam splittings and unconformities. Only a few studied seams reveal stable thickness and wide extension over several deposits. Moreover, the fault systems cutting through the coal formation are poorly recognized. The study concerns the parameters of 3 most extended seams (covering 7-9 deposits) and showing high coal abundances. Source data originated from, totally, 261 to 308 exploration boreholes. Within particular deposits, the number of boreholes varied from 16 to 50. The statistical and geostatistical analysis embraced 4 principal coal deposit parameters: thickness of seams, sulphur and ash contents, and bulk density of coal. The statistical methods included determination of basic statistical parameters of studied deposit parameters and empirical distributions of parameters with the "box and whisker" plots, and analysis of their homogeneity within particular seams using the Games-Howell multiple range tests. Variability structure of parameters within the seams was analyzed with the empirical semivariograms. The results gave rise to evaluation of heterogeneity of deposit parameters. This, in turn, led to the selection of groups of deposits in which mean values of analyzed deposit parameters are homogenous.