The well in Poland’s northern Baltic basin was recently hydraulically fractured, with oil flowing to the surface.

San Leon and joint venture partner Wisent Oil & Gas now consider Braniewo S to have proven oil potential in the Cambrian and overlying sandstone.

The three-stage fracturing programme confirmed different oil qualities in the different targets.

The “highly-encouraging results” confirmed the need for a second phase of appraisal.

San Leon executive chairman Oisin Fanning said the drilling confirmed the presence of mobile oil.

“We look forward to drilling the next exploration well and shall promptly evaluate which of the two targets to drill first in order to prove up a commercial oil accumulation,” he said.

Joint venture partners are now reviewing two options for...