General information and occurrence
In Poland, the main area of the documented natural gas fields occurrence is the Polish Lowlands. Gas fields have been also documented on the Carpathian Foreland, minor resources occur also in small deposits within the Carpathian Mts. area and in Polish economic zone of the Baltic Sea (map). About 75% of the documented gas resources are related to plays involving Miocene and Rotliegend formations and the remaining resources – to plays in the Cambrian, Devonian, Carboniferous, Zechstein, Jurassic and Cretaceous formations.
In the Polish Lowlands, the gas fields are related to the sediments of the Permian age in the Fore-Sudetic and Wielkopolska regions and of the Carboniferous and Permian age in the Western Pomerania. In these regions the gas occurs in the massive- and block-type fields with the water- or gas-drive exploitation mechanism. In that area only a few gas fields contain high methane gas, the remaining gas fields contain the nitrogen natural gas as the main component with the content of methane ranging from about 30% up to over 80%. Therefore, that is a nitrogen-methane or methane-nitrogen mixture.
The fields containing natural gas with a nitrogen content over 90%, called as „high nitrogenous natural gas” (HNNG), are discussed in a separate section.
On the Carpathian Foreland, natural gas fields are related to plays involving the Jurassic, Cretaceous and Miocene formations. Most often, the fields contain high methane natural gas with a low content of nitrogen. The exceptions are few natural gas fields containing high nitrogen concentrations. In this region gas occurs in the structural-lithological multi-layer traps or, sometimes massive-type reservoirs with the gas drive mechanism.
In the Carpathians, the natural gas occurs in self-contained fields or as an accompanying element in crude oil or condensate fields related to plays in the Cretaceous and Paleogene formations. The gas is characterized by a high content of methane (usually over 85%) whereas an average content of nitrogen is a few percent.
In the Polish economic zone of the Baltic Sea the gas occur as a self-contained in B 4, B 6, B 21 fields and together with crude oil in B 3 and B 8 fields.
At present, the Polish Lowlands region accounts for 73.4% of exploitable domestic resources of natural gas and the Carpathian Foreland – for 21.9% of those resources. The resources of the Polish economic zone of the Baltic Sea and the Carpathians are subordinate (accounting for 3.6% and 1.1% of exploitable domestic resources, respectively).
Resources and output
Table 1 shows exploitable resources of natural gas exploited from the gas fields, crude oil and condensate fields, taking into account the degree of their exploration and the state of development. The data given in the table refer to the resources of natural gas of various methane content and are not converted to those of high methane gas (high methane gas = extracted reserves x combustion heat of real gas / combustion heat of high methane gas, that is about 34 MJ/m3).
In 2020, the exploitable resources of natural gas amounted to 143.92 billion m3 (the total anticipated economic and anticipated sub-economic resources) and in comparison with the previous year decreased by 0.33 billion m3. There were new field included in “The balance…” in 2020 – Gnojnica (documented exploitable anticipated economic resources 148.59 million m3). The most significant resources growths were recorded for Brońsko field (the including new wells into the exploitation, the activities improving the exploitation) and in Trzebusz field (the approval of the geological-investment documentation), Paproć field, Załęcze field (mainly the better field exploration by the ongoing exploitation and the activities improving the exploitation). The resources drops were caused mainly by the exploitation.
The exploitable resources of exploited fields were estimated at 95.81 billion m3, which accounts for 66.6% of the total amount of the exploitable resources.
In 2020, the economic resources of natural gas fields were equal 73.51 billion m3.
The total domestic resources given above include those of gas fields which are planned to be converted for the use as the underground natural gas storage facilities. The resources remained in these fields are treated as a gas cushion (a buffer capacity) and will not be exploited in the time of the natural gas storage existence. There have been the following gas fields selected for conversion into underground storage facilities: Bonikowo (328.63 million m3), Brzeźnica II (45.59 million m3), Daszewo (27.72 million m3), Husów (372.88 million m3), Strachocina (121.5 million m3), Swarzów (28.80 million m3) and Wierzchowice (5,728.12 million m3). The total resources of natural gas to be used as gas cushions are estimated at 6,653.25 million m3. In 2012, there was a permission given by the Minister of the Environment for Henrykowice E field (crossed out from “The balance…” in 2003) to be used as underground natural gas storage facility.
The underground hydrocarbons storage facilities are also built in the salt deposits. There are 3 cavernous underground facilities operating at the moment – gas storage facilities Mogilno II and Kosakowo and the crude oil and liquid fuels storage facility Góra. As of the end of 2020, 11 licenses for running underground natural gas, crude oil and liquid fuel storage facilities were valid.
In 2020, the domestic output of natural gas from the fields with documented gas resources (Table 2) was equal 4,933.98 million m3, being by 42.48 million m3 lower than in 2019.
The figure below shows changes in domestic exploitable anticipated economic resources and production of natural gas in Poland in the years 1989-2020.
The list of natural gas fields with their resources, the output and the state of development is presented in Table 3. The fields which have been abandoned due to the exploitable resources depletion have anticipated economic or anticipated sub-economic resources documented.
The prospective resources of the conventional natural gas, according to The balance of prospective mineral resources of Poland, are connected with the oil-gas-bearing formations occurring: on the Polish Lowlands (the Cambrian formation – about 1.3 billion m3, the Devonian-Carboniferous formation – about 56.22 billion m3, the Rotliegend formation – about 1,410 billion m3, the Main dolomite formation – about 219 billion m3, the Mesozoic formation – probable resources about 11.25 billion m3 and hypothetical resources 55.22 billion m3), on the Carpathian Foreland (the Miocene together with its basement in the Carpathian Foredeep – about 57.1 billion m3, the Carpathian flysh together with its basement – about 30.6 billion m3)*. The long-term prospective outlooks are connected with: the western and eastern part of the Carpathian Mts. and the Carpathian Foreland (especially the compaction anticlines below the Miocene sediments), the Carboniferous sediments of the north-eastern edge of the Western European platform, the Rotliegend formation occurring on the large depths of 3,500-6,500 meters, the area of the western parts of Main dolomite platforms and the eastern part of the Fore-Sudetic Monocline. The resources of the unconventional natural gas (technically exploitable) in the land area within schists of Lower Paleozoic age in the Baltic-Podlasie-Lublin basin are assessed to be equal about 75.3-622.2 billion m3, whereas on the maritime area to be equal about 126.7-166.1 billion m3**. Regarding the natural gas trapped in the Rotliegnd sandstones of the Poznań-Kalisz zone, the Carboniferous sandstones of the Wielkopolska-Śląsk zone and the Cambrian sandstones in the western part of the Baltic basin, their total geological resources are assessed to be equal 1,528-1,995 billion m3, which recalculated to the technically exploitable resources is about 153-200 billion m3.
Prepared by: Martyna Czapigo-Czapla, Dariusz Brzeziński
* Feldman-Olszewska A., Kiersnowski H., Peryt T., Pacześna J., Laskowicz R., Janas M., Głuszyński A., Waśkiewicz K., 2020 - Ropa naftowa (crude oil), gaz ziemny (natural gas), kondensat ropno-gazowy (condensate). In: Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31.12.2018 r. (eds. Szamałek K., Szuflicki M., Mizerski W.): 49-69. PIG-PIB, Warszawa [in Polish].
** Wójcicki A., Kiersnowski H., Podhalańska T., Janas M., Głuszyński A., Pacześna J., Adamczak-Biały T., 2020 - Gaz i ropa z łupków (shale gas, shale oil), gaz zamknięty (tight gas). In: Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31.12.2018 r. (eds. Szamałek K., Szuflicki M., Mizerski W.): 70-83. PIG-PIB, Warszawa [in Polish].