Tectonic position, hydrocarbon exploration and future potential of Bulgaria

Abstract

The Phanerozoic geological history of Bulgaria is extremely rich in large scale phenomena which have caused the present-day variety of specific and disparate tectonic units on the territory of the country. The main large regions are the Moesian Platform and part of the Alpine orogen, as well as the slope and the foot of the deep-sea megadepression in the Black Sea to the east. The better studied Meso-Neozoic history is based on the relations between the stable Eurasia and the northern margin of the Paleo- and Neo Tethys. Paleoalpides (Old Kimmerides and Austrides), Mezoalpides (Subhercynian and Laramie) and Neoalpides (Illirian-Pyrenean) have been recognized. The geological structure and first of all the tectonic setting are an objective prerequisite for comparing the results available of oil- and gas exploration and for directing future works. The main productive fields occur in Triassic, Lower-Middle Jurassic, Valanginian and Paleogene sediments. They are mainly concentrated in the southern part of the platform and some adjacent parts of the Forebalkan where topography has favoured some seismic studies. The whole hydrocarbon potential is not completely known because of the large number of areas that in fact have not been studied. These are the southern parts of the Forebalkan, the Balkan, the northern parts of the Srednogorie, the southern shelf, the Paleozoic sediments in the platform, the continental slope (especially its prograde parts and the foot). The necessity of their study with modern techniques and technology is determined by the favourable conditions for the oil- and gas search which is demonstrated by some concrete data and by research results obtained so far.