In 2015, there were 86 crude oil fields documented in Poland – 29 of these fields are situated in the Carpathian Mts, 12 in the Carpathian Foreland, 43 within the Polish Lowlands and 2 in the Polish economic zone of the Baltic Sea. Oil fields occurring in the Carpathian Mts and Carpathian Foreland have had a long history as this is the area of the world's first commercial production of crude oil. However, nowadays these fields are almost exhausted. Nowadays, the Polish oil fields of the largest economic importance are situated in area of the Polish Lowlands. In 2015, resources of the Polish Lowlands accounted for 74% of total exploitable crude oil resources of Poland. Resources of the Polish economic zone of the Baltic Sea were the second largest, accounting for 20% of the total exploitable resources. Resources of the Carpathian Foreland and Carpathian Mts accounted for 4% and 2% respectively.
In the Polish Lowlands, oil fields are related to traps in the Permian, Carboniferous and Cambrian rocks. Polish Lowlands oil is of the medium paraffin type, with paraffin content ranging from 4.3% to 7.4%, content of sulfur slightly above 1% and density ranging from 0.857 g/cm3 to 0.870 g/cm3. The majority of these traps are of the massive type, with gas cap expansion drive and with passive role of water. Barnówko-Mostno-Buszewo oil and gas field is the largest one in Poland. Its resources of crude oil were found to be twice bigger than the total domestic resources before its discovery. Other large oil fields situated in this region include Lubiatów, Grotów and Cychry oil fields.
In the Carpathian Mts, oil fields occur in several tectonic units, mainly in the Silesian unit. The oil fields are related to traps of the structural or sometimes structural-lithological type, mainly of the type of oil layer surrounded by water. Production is initially driven by the expansion of natural gas dissolved in oil and subsequently by gravity driven drainage.
Carpathian crude oils represent the methane type and are considered "sweet” because of negligible content of sulfur. Their density ranges from 0.750 g/cm3 to 0.943 g/cm3 and content of paraffin – from 3.5% to 7.0%. Resources of Carpathian oil fields are generally small, depending on size and character of structures which they are related with. The resources are largely exhausted in result of many years of exploitation.
The Carpathian Foredeep oil fields are related to traps in Miocene rocks, in Mesozoic sedimentary rocks (Jurassic carbonate rocks and sometimes Cretaceous sandstone series) of the platform type usually sealed with layers of impermeable Miocene clays. Crude oil density ranges from 0.811 g/cm3 to 0.846 g/cm3, content of paraffin from 2.32% to 9.37% and sulfur content from 0.45% to 0.85%.
Resources of developed oil fields account for 96% of total domestic resources.
Some of the fields located in the regions mentioned above contain dissolved gas components forming oil condensate. In the Polish Lowlands oil condensate occur in Cychry field and (in lesser amounts) in Babimost, Jastrzębsko and Antonin 1 fields. In the Carpathian Foreland oil condensate occur in the Łąkta field and in the Carpathian Mts in little amounts in Słopnice field.
There are crude oil fields occurrying in Poland presented on the map.
The table 1 shows resources of oil and condensate and the current state of their exploration and development.
In 2015, exploitable resources of crude oil and condensate totaled 23,219.68 thousand tonnes (anticipated economic and subeconomic resources), decreasing by 706.99 thousand tonnes in relation to the previous year. That was mainly due to the exploitation. Moreover, the output from Kosarzyn E, Kosarzyn N and Breslack-Kosarzyn fields was stopped. There was one new field documented in 2015 – Sieraków (with exploitable resources equal 157.81 thousand tonnes).
Domestic production of crude oil and condensate from onshore and offshore totaled 898.87 thousand tonnes in 2015, decreasing by 19.88 thousand tonnes in relation to the previous year. Table 2 shows crude oil and condensate production in individual regions of the country.
The figure below shows changes in exploitable anticipated economic resources and production of oil in Poland in the years 1989-2015.
Prepared by: Martyna Czapigo-Czapla, Dariusz Brzeziński