Britain's JKX Oil & Gas said the Shkorpilovtci South West R-01 exploration well in east Bulgaria spudded successfully on October 17.
The company noted that the well is targeting an amplitude supported channel sand complex of late Eocene age.
Results from the well, which will drill to a proposed total depth of 900m, are expected in early November.
Prospective resources for this feature are estimated at 20-30 Bcf (gross).
Earlier this month the British company, operator of the B1-Golitza license in Bulgaria, announced it has plugged and abandoned the Staro Oryahovo South R-01 exploration well in the eastern part of the country.
The company started at the beginning of September a two-well drill program in the country to test targets with an estimated resource of up to 60 billion cubic feet (Bcf).
The Staro Oryahovo South R-1 well was drilled to test a submarine fan target of Eocene age in the Kamchia Basin, south west of Varna, Bulgaria.
After the drilling was complete the rig was moved to the Shkorpilovtci South West R2 location, 5km to the south.
JKX Oil & Gas signed at the end of May on a CCC-500 drilling unit through Weatherford for two wells in Bulgaria's onshore B1-Golitza Block.
Interests in the B1-Golitza block are held by JKX (40%), Balkan Explorers (Bulgaria) Limited (a 100% subsidiary of Aurelian Oil and Gas PLC) (30%) and Sorgenia International B.V.