In Poland, the main area of a 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 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 72% of exploitable domestic resources of natural gas and the Carpathian Foreland – for 23% of those resources. The resources of the Polish economic zone of the Baltic Sea and the Carpathians are subordinate (accounting for 3% and 1% of exploitable domestic resources, respectively).
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 2018, the exploitable resources of natural gas amounted to 142.16 billion m3 (anticipated economic and anticipated sub-economic resources in total) and increased by 22.97 billion m3 in comparison with the previous year. In 2018 there were new fields included in “The balance…”: B 21 (documented exploitable anticipated economic resources equal 275 million m3), Jata (13.67 million m3), Krobielewko (25,886.50 million m3) and Miłosław (201.14 million m3). There were Porażyn field crossed out from the domestic balance. The most significant resources growths resulted from the approving of further documentations were recorded for Pruchnik-Pantalowice and Młodasko fields.
The exploitable resources of exploited fields were estimated at 90.56 billion m3, which accounts for 64% of the total amount of the exploitable resources.
In 2018, economic resources of natural gas fields were equal 66.64 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 7 gas fields selected for conversion into underground storage facilities so far: 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 6.65 billion 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 2018, 11 licenses for running underground natural gas, crude oil and liquid fuel storage facilities were in force.
In 2018, the domestic output of natural gas from the fields with documented gas resources (Table 2) was equal 4,926.01 million m3, being by 83.11 million m3 lower than in 2017.
The figure below shows changes in domestic exploitable anticipated economic resources and production of natural gas in Poland in the years 1989-2018.
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.
Prepared by: Martyna Czapigo-Czapla, Dariusz Brzeziński