Natural gas fields occur in the Polish Lowland: pre-Sudetic and Wielkopolska regions and in the Western Pomerania (Pomorze Zachodnie) as well as in the Carpathian Foredeep and off shore Baltic Sea. The gas occurs in separate fields or together with oil or oil condensate. Majority of the gas resources are to be found in the Rotliegendes and Miocene sediments, the remaining occurs among others: in the Carboniferous, Zechstein, Jurassic and Cretaceous rocks (see map). In the Polish Lowland, gas fields occur mainly in the pre-Sudetic and Wielkopolska regions (Permian sediment) as well as in the Western Pomerania (Carboniferous and Permian rocks). The gas has usually a high nitrogen contents (from a dozen or so to over 80 %). There are, however, fields in Zechstein Main Dolomite with nitrogen contents of 95.7 - 97.6 % and only 3.1 % of methane. The resources in each region have changed in recent years, which is due to the new gas resources found in the Bronsko, Koscian, BMB, Międzychod and Lubiatow deposits in the Polish Lowland. In 2004 66,5 % of the proven initial resources occurred in Lowland fields. Resources of the Carpathian Foredeep accounted for 29 % of the country resources, Baltic Sea resources accounted for 3,2 %, while the Carpathian resources for only about 1 %. In the Carpathian Foredeep, the gas fields occur in the Jurassic, Cretaceous and Miocene sediments. The gas has a high methane and low nitrogen content (from about 70 % to 98.8 % of methane and 3-22 % of nitrogen). These are structural-lithological, multibedded, sometimes massif fields, occurring in gas-pressure conditions. In Table 33.1 the recoverable resources/reserves of natural gas are presented taking into account the degree of geological exploration and management. Table 33.1 Natural gas (million m3)
* total, ** in oil and oil condensate fields, *** in gas fields, **** underground gas stores (PMG) The recoverable proven resources of natural gas amounted to 154,355 million m3 (as of December 31, 2004). The resources of the exploited gas fields amounted to 127,722 million m3, which constituted 82.7 % of their total amount. From the total of 256 gas fields 183 fields (71.5 %) are under exploitation. The total economic reserves amounted to 80,723 million m3 in 2004. The fields intended for stores of natural gas have been excluded from exploitation. The reserves left in the gas fields are treated as a gas pillow (buffer capacity) and will not be exploited as long as the stores exist. By the end of 2004 six fields with a total reserve of 4,749 million m3 had been designated for underground stores. The gas output amounted to 5,228.92 million m3 in 2004. The gas resources and their exploitation in Poland for the period between 1989 and 2004 are shown in Fig 33.1. In 2004, the gas output covered 43.2 % of the country’s demand. The deficit was balanced by imports that amounted to 6,226 million m3 (mainly from Russia 59.6 %). The directions and quantities of gas imports and exports are shown in Table 33.2. Prognostic gas resources, estimated at about 650 billion m3, demonstrate possibility of finding new fields. The most prognostic resources occur in the Polish Lowland 75 %, the Carpathian Foredeep and the Carpathians account for 21 % and 4 %, respectively.
Table 33.2 Directions of Polish imports and exports of natural gas
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