Geological structure and prospects of oil-gas presence at the Pohar plot (Folded Carpathians)

Abstract

The Pohar plot is situated in the Skole district of the Lviv Region, 30 km south-west of Skole town, between Pohar and Kryve villages. Tectonically it is located in of junction of the Skybian (Slavske Skyba) and the Krosno covers. At the end of XIX beginning of XX centuries in the region of the village the oil-extracting enterprise was existent. There deposits of Oligocen and Eocene of the Rozluch belt of the Krosno cover and Oligocene of the scale of the Slavske skyba of the Skybian cover were exploited. During two ten-years of exploitation by exploring shafts and shallow boreholes more than 3 thousand ton of oil was extracted. Prospects of the Pohar plot should be connected with sand horizons of the Holovets suite of Oligocen (Klivsky sandstones) that are characterized by satisfactory reservoir properties. They are localized in the immersed part of the Hrosivsky scale of the Krosno cover separated by the Rozluch fault (tectonically screened deposit) from its forkball part, drilled in 1973–1974 1-Pohar borehole (well bottom 1935 m), due to deflection of its hole to the south-east, didn’t expose the Klivsky sandstones and didn’t solve its task. For complete exposition of the Klivsky sandstones of the Holovets suite of Oligocene of the Hrosivsky scale it is necessary to design vertically oriented 2-Pohar borehole of 2300 m in depth. About probable commercial oil-gas saturation of the horizon of the Klivsky sandstones testifies not only to the existence of the oil-extracting enterprise in the past, but the intensive surface oil shows in the stretched area that is controlled by the Rozluch fault. Moreover, taking the prospect of the zone of junction of the given covers in consideration, the seismic survey should be conducted at the Pohar area for the estimation of the geological structure of the deeper horizons and parametric borehole of 4000–5000 m in depth should be designed.