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AGH-University of Science and Technology,Faculty of Geology Geophysics and Environmental Protection, Department of Fossil Fuels, Al.Mickiewicza 30, 30-059 Kraków, Poland
LOTOS Petrobaltic S.A. ul. Stary Dwór 9, 80-758 Gdańsk
Publish date: 2017-07-01
J. Ecol. Eng. 2017; 18(4):100–109
The emission of geogenic methane and carbon dioxide contributes to the world climate changes. The results of studies run worldwide demonstrate that the emission of geogenic gases strongly influences the increasing concentrations of greenhouse gases in the atmosphere, including methane and carbon dioxide. The Outer Carpathians reveal significant hydrocarbon potential and host numerous macro- and microseepages of hydrocarbons including the natural gas. Migration of hydrocarbons from deep accumulations towards the surface is controlled by diffusion and effusion. It appears that the Carpathians may play significant role as a supplier of greenhouse gases to the atmosphere.Before the World War II, oil macroseepages were the principal premises in petroleum exploration. In the Carpathians, hydrocarbons have been exploited since the XIX century. Unfortunately, most of discovered oil and gas deposits are recently only the historical objects. An example is the Sękowa-Ropica Górna-Siary oil deposit located in the marginal part of the Magura Nappe where oil has been extracted with dug wells until the mid XX century. One of such extraction sites is the "Pusty Las" oilfield. In that area, 10 methane and carbon dioxide emission measurement sites were located, among which 4 in dried dug wells and 6 in dig wells still filled with oil and/or water. Dynamics of methane and carbon dioxide concentration changes were measured with the modified static chambers method. Gas samples were collected immediately after the installation of the chamber and again, after 5 and 10 minutes. In the case of reclaimed or dry dug wells, static chamber was installed directly at the ground surface. In wells still filled with oil and/or water the chamber was equipped with an "apron" mounted on special sticks.The dynamics of concentrations changes varied from -0.871 to 119.924 ppm∙min-1 for methane and from -0.005 to 0.053 %obj∙min-1 for carbon dioxide. Average methane emission was 1.8 mg∙m-2∙d-1 and that of carbon dioxide was 26.95 mg∙m-2∙d-1. The measurements revealed that an abandoned oil field supplies significant amounts of greenhouse gases to the atmosphere although the emission of methane is lower than that measured e.g. in mud volcanoes located in various part of the world.