DOI: 10.5593/sgem2012/s05.v2004


Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 2, 457 - 462 pp


Central North Bulgaria occupies a wide area in the Moesian Platform and its southern
platform margin. The territory has been a major exploration target in searching for oil
and gas since 50 years now. The most of the economic fields are concentrated in the
western and south-western parts of Central North Bulgaria. The oil and gas fields are
connected with Middle Triassic carbonates (Doirentsi Formation), Lower Jurassic basal
sandstones (Kostina Formation), Lower-Middle Jurassic dolomites (Ozirovo Formation)
and Lower Cretaceous carbonates (Kaspichan Formation). All of them confirm a higher
petroleum perspective of Central North Bulgaria and future exploration possibilities.
However, the present paper presents the special features of the non-economic
hydrocarbon accumulations, discovered by bore-holes in the southern part of Central
North Bulgaria. The study area includes the South Moesian Platform margin and the
territory along its northern boundary with the Moesian Platform. Besides the
hydrocarbon deposits in the Triassic and Lower-Middle Jurassic rocks there are small
accumulations, shows, oil stains, bitumens and water dissolved gases localized also in
other stratigraphic levels.
Some of the oil accumulations in the sedimentary section are bound up with buried
positive structures. It is worth noting the small discoveries near villages Gradina and
Bohot as well as many hydrocarbon shows through the entire Mesozoic sequence at
Krushovitsa and several other bore-hole locations. The oil in Gradina is accumulated in
Aptian sandstones and the oil close to Bohot in Middle Jurassic carbonates. The
hydrocarbons in the accumulations and multiple bore-hole shows at Beglej, Bejanovo,
Suhindol, Agatovo, Karpachevo and many others are characterized with a composition
and physical conditions, which to a great extent are similar to those in the economic
fields. They are predetermined by the probable common source of generation as well as
the burial depths. The quality of the hydrocarbons varies in wide ranges from gases
mainly with methane, gas-condensate to light oil.

Keywords: Central North Bulgaria, Moesian Platform, oil and gas fields, small
hydrocarbon accumulations and shows.