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Abstract: Methane in the Upper Silesian Coal Basin (Poland) - Problem of Reserves and Exploitation

Andrzej J. Wojcik

The Upper Silesian Coal basin (USCB) is the best recognized and the most productive coal basin in Poland. The USCB is primarily defined by the extent of Carboniferous coal-bearing formations. The sedimentary fill displays the stratigraphic record of major progressive inversion phases of the entire Moravo-Silesian basin during the late and post-geosynclinal period of the Variscan orogeny.

According to the last estimates the coal reserves occurring above the depth limit of 1500 m are as follows: documented reserves - 58 billion tons, prognostic reserves - 46 billion tons, total - 104 billion tons. The coal type is predominantly vitrinitic, and ash content is reported to be in the range of 11-17% and average sulphur content is 1.13 %. The rank of USCB coal is largely controlled by complex coalification processes. It ranges from high volatile bituminous B, through medium volatile bituminous to high rank special coal semi anthracite and anthracite.

The methane content of coal seams in USCB varies in a very broad range of 0-22 m3/t coal (dry, ash free basis). The average gas content increases considerably within the depth range 600-1000 m from 0.99 to 4.68 m3/t coal (daf). In deeper horizons it is more or less stable varying within the range of 4.7-7.0 m3/t coal (daf). By this estimate, on average, the methane content is about 12.5 m3/ton. There are several estimates of coal-bed methane resources in the USCB based on different methods. The resources are as follows: documented deposits in active mines to 1000 m: 370 BCM, undeveloped deposits to 1000 m: 340 BC M, deposit between 1000 and 1500 m: 590 BCM, total: 1300 BCM. The coalbed gas from this basin is primarily composed of saturated hydrocarbons and Nitrogen which amount to 97 volume percent. The rest is dominant by Carbon dioxide and Hydrogen.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France